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Speedster22i DDR3 Controller User Guide

UG031 – Nov 18, 2014

UG031, Nov 18, 2014 1

Copyright Info

Copyright © 2014 Achronix Semiconductor Corporation. All rights reserved. Achronix is a trademark and Speedster is a registered trademark of Achronix Semiconductor Corporation. All other trademarks are the property of their prospective owners. All specifications subject to change without notice.

NOTICE of DISCLAIMER: The information given in this document is believed to be accurate and reliable. However, Achronix Semiconductor Corporation does not give any representations or warranties as to the completeness or accuracy of such information and shall have no liability for the use of the information contained herein. Achronix Semiconductor Corporation reserves the right to make changes to this document and the information contained herein at any time and without notice. All Achronix trademarks, registered trademarks, and disclaimers are listed at http://www.achronix.com and use of this document and the Information contained therein is subject to such terms.

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Table of Contents

Table of Figures ................................................................................................. 4

Features ............................................................................................................. 6

Introduction ....................................................................................................... 7

Interfaces ........................................................................................................... 9

Internal (core) Interface .......................................................................................................... 9

External (off-chip) Interface .................................................................................................. 11

Parameters .......................................................................................................................... 11

Address Mapping ............................................................................................ 14

Write Interface Details ..................................................................................... 15

Back-to-Back Write Protocol 2X Clock Mode ....................................................................... 19

Write Protocol with Wide Bus Interface Enabled .................................................................. 21

Read Interface Details ..................................................................................... 23

Back-to-Back Read Protocol 2X Clock Mode ....................................................................... 25

Read Protocol with Wide Bus Interface Enabled .................................................................. 27

Memory Interface Latency .............................................................................. 30

Customization using ACE ............................................................................... 31

Revision History .............................................................................................. 32

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Table of Figures

Figure 1: Location of Speedster22i DDR Controllers and PHYs ............................................................... 5 Figure 2: Top-level Overview of Embedded DDR Control Logic ............................................................... 7 Figure 3: Address mapping of ‘ddr_int_addr’ Signal ............................................................................... 14 Figure 4: Write Interface 2X Clock Mode ................................................................................................. 15 Figure 5: Internal Interface Write Protocol Timing Diagram .................................................................. 16 Figure 6: Internal Interface Write Protocol Timing Diagram with default value ‘addrcmd_delay’ to 8 . 17 Figure 7: Write Protocol Timing Diagram (SDRAM Interface) ............................................................... 18 Figure 8: Write Protocol Timing Diagram (Write requests with valid writes highlighted)...................... 19 Figure 9: Write Protocol Timing Diagram (ddr_int_wrdata_req corresponding to respective writes highlighted) ............................................................................................................................................... 20 Figure 10: Write Interface with Wide Bus Interface Enabled ................................................................... 22 Figure 11: Internal Interface Write Protocol Timing Diagram with Wide Bus Interface Enabled .......... 22 Figure 12: Read Interface 2X Clock Mode ............................................................................................... 24 Figure 13: Internal Interface Read Protocol Timing Diagram ................................................................. 24 Figure 14: External Interface Read Protocol Timing Diagram ................................................................ 25 Figure 15: Read Protocol Timing Diagram (with valid read request highlighted) .................................. 26 Figure 16: Read Protocol Timing Diagram (with ddr_int_rddata_valid highlighted) ............................. 26 Figure 17: Read Interface with Wide Bus Interface Enabled ................................................................... 28 Figure 18: Internal Interface Read Protocol Timing Diagram with Wide Bus Interface Enabled ........... 28 Figure 19: DDR3 Customization using ACE ............................................................................................ 31

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Overview

Achronix’s Speedster22i FPGAs contain up to six embedded DDR controllers which can be used to interface with and control off-chip DDR2 or DDR3 memory devices, including DIMMs. Each of the DDR controllers supports up to 72 bits of data and speeds of up to 1866 Mbps. The embedded DDR controllers and PHYs are implemented as Hard-IP blocks in the frame of the Speedster22i FPGAs as illustrated in Figure 1 below.

Figure 1: Location of Speedster22i DDR Controllers and PHYs

Speedster22i DDR controllers support both “auto” and “custom” modes. Under the “auto” mode functions such as (but not limited to) activating/precharging banks/rows, calibration algorithms, and initialization sequences are handled by the embedded DDR Controller and are transparent to the user. The mapping of byte-lanes to pins is also handled transparently as the IOs are included in embedded DDR PHY Macro.

Under “custom” mode the user has the option to manually override functions such as automated refresh and initialization engines/sequences.

Speedster22i FPGA

DDR PHY

DDR Controller

DDR Memory(off-chip)

Speedster22i Core

WN

WS

EN

ES

ECWC

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Features

The features supported by the embedded DDR controllers are highlighted below:

• 1866 Mbps data rate

• The controller and PHY can run at 1066 MHz to achieve 1866 Mbps rate at the memory interface. A 2X Clock setting enables the core to run at half the speed -533MHz. There is an additional feature to enable a wide bus interface, which effectively enables the core to run at one quarter the speed - 266MHz. The 2X clock setting and wide bus interfaces can be enabled at any data rate, thereby reducing the core frequency by half, or a quarter, respectively.

• 4 Chip Selects per controller

• The external memory connected to each controller can comprise of up to 4 ranks (either two dual-rank DIMMs or one quad rank DIMM)

• Registered DIMM and Unbuffered DIMM support

• Each controller can independently support either rDIMMs or uDIMMs

• Address mirroring is supported.

• Multi-Burst Mode

• Each controller supports multi-burst mode, up to a burst length of 252 (DDR2) / 254 (DDR) / 248(DDR3). This allows the embedded controller to automatically issue up to 252 cascaded read or write commands to automatically increment addresses based on a single command from the Core Fabric

• Backwards Compatible

• The embedded DDR controllers can support DDR3 (up to 1866 Mbps), DDR2 (up to 800 Mbps) and DDR protocols

• Bypassable

• If the user does not require all six DDR controllers, any (or all) can be bypassed to leverage use of the designated I/Os for other purposes

• If the user does not require all 72-bits of the data bus, unused byte lanes can be bypassed to leverage use of the designated I/Os for other purposes

• Minimal LUT use

• The DDR controllers are embedded (hardened), and therefore do not use any of the LUTs in the core fabric

• LUTs are only required to interface the DDR Controllers

• Zero License fees

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Introduction

Speedster22i devices contain up to six embedded (Hardened) DDR Controllers. The instantiatable macros for these are called ‘ddr3_xSIZE1_LOCATION2’ where size can be configured as 72,64,32,16 or 8 and location can be EN,EC,ES,WN,WC,WS for a device with six controllers, such as the Speedster22i HD1000. Each Macro is comprised of a DDR Controller and a DDR PHY, and is controlled by the user by means of the DDR driver logic.

The DDR3 controller macros manage the interface between the DDR driving logic (housed within the Core Fabric) and the off-chip DDR memory itself. A more detailed description of these interfaces is illustrated in Figure 2 below.

Speedster22i

DDR Control Macro

ACX_PLL

DDR Controller

clk

sd_dummy[8:0]

sd_dm[8:0]

sd_dqsn[8:0]

sd_dqsp[8:0]

sd_dq[71:0]

sd_cke[3:0]

sd_clk_out_p[3:0]

sd_clk_out_n[3:0]

sd_reset_n

sd_cas_n

sd_ras_n

sd_we_n

sd_a[15:0]

sd_ba[2:0]

sd_cs_n[3:0]

sd_odt[3:0]

Read/Write Shared Interface

Write Interface

Read Interface

General Memory Control Interface

Manual refresh control Interface

Control Interface

DDR Internal Interface (User Logic)

ddr_int_clk_div2

ddr_int_zq_cal_ack

ddr_int_ref_ack

ddr_int_busy_align

ddr_int_busy

ddr_int_wrdata_valid

ddr_int_wrdata_req[8:0]

ddr_int_wrdata_req_early[8:0]

ddr_int_wrdata_req_align[8:0]

ddr_int_wrdata_req_early_align[8:0]

ddr_int_rddata[287:0]

ddr_int_rddata_valid [8:0]

ddr_int_rddata_valid_align[8:0]

ddr_int_rddata_valid_early[8:0]

ddr_int_rddata_valid_early_align[8:0]

ddr_int_init_ack

ddr_int_init_wlvl_done

ddr_int_cmd_auto_pch

ddr_int_cmd_self_refresh[1:0]

ddr_int_addr[33:0]

ddr_int_burst_size[7:0]

ddr_int_wr_request

ddr_int_wrdata[287:0]

ddr_int_wrdata_mask[17:0]

ddr_int_rd_request

reset_ddr_ctrlr_n

reset_ddr_phy_n

ddr_int_phy_ci_slave_dqsn_en

ddr_int_cmd_power_down[1:0]

ddr_int_cmd_ref_req

ddr_int_cmd_zq_cal_req[1:0]

ddr_int_phy_ci_slave_adj

DDR PHY

ExternalDDR Memory

Figure 2: Top-level Overview of Embedded DDR Control Logic

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The embedded DDR controller macro function performs:

• All required initialization sequences such as the programming of AL and CL values based on user-defined parameters

• All required calibration algorithms. This includes

Write levelization

DQS Enable (to control read-write turnaround of DQ/DQS bi-directional busses)

DQS Delay (to skew the DQS by 90 degrees relative to the corresponding DQ, such that the latter can be sampled in the middle of the bit transition)

• Translation of READ and WRITE requests received from the DDR driver into DDR protocol i.e. RAS, CAS and WE

• Translation of data to and from SDR to DDR

• Maintaining integrity of memory contents by issuing periodic auto-refresh and zqcal commands

• Managing the activating and pre-charging of memory banks and rows, as required

• Managing the driving of the memory address pins (with column or row information, as well as A10 function (precharge-all, auto-precharge, etc)

• Providing a data request signal (‘ddr_int_wrdata_req’) to the DDR driver logic, some number of cycles after a corresponding write transaction request is received. The customer logic should be capable of reacting to ddr_int_wrdata_req correctly”. This ensures that CAS latency, additive latency and burst length are all managed internally to the Speedster22i DDR controller. It also provides early data request signal (‘ddr_int_wrdata_req_early’) which can be used if more time is required to generate data.

• Provides data request signal (‘ddr_int_wrdata_req_align’) and early data request signal (‘ddr_int_wrdata_req_early_align’) because the wide bus interface or 2X Clock mode should always be selected for 1866Mpbs.

• Providing a read data valid signal (‘ddr_int_rddata_valid’) to accompany read data provided in response to a read request. This ensures that the round-trip latency to (and through) the memory is managed internally to the Speedster22i DDR controller. It also provides early data valid signal (‘ddr_int_rddata_valid_early’) which can be used to latch read data.

• Provides data request signal (‘ddr_int_rddata_valid_align’) and early data valid signal (‘ddr_int_rddata_valid_early_align’) if the wide bus interface or 2X Clock mode is selected for 1866 Mbps.

• Provide signal (‘ddr_int_busy’) to DDR Driver logic to indicate that the DDR3 Controller is busy and is not accepting new requests.

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Interfaces

Internal (core) Interface The internal interface to the PHY/DDR controller, which is implemented in the core fabric, contains the following interface signals as listed below in table 1.

Signal Name Bus Width Direction Description

clk 1 Input Driven by user. Clock signal. This is the reference clock coming in from the board.

ddr_int_clk_div2 1 Output In 2X Clock mode the clock from PHY will be at half the controller clock which should be used to send and receive data from core to controller

ddr_int_clk_div4 1 Output When the wide bus interface is enabled, the clock from PHY will be at one quarter the controller clock which should be used to send and receive data from core to controller

reset_ddr_phy_n 1 Input Driven by user. Reset to PHY. Asserted active low. reset_ddr_ctrlr_n 1 Input Driven by user. Reset to DDR controller. Asserted active low.

ddr_int_busy 1 Output Indicates that the DDR3 Controller is busy and is not accepting new requests.

ddr_int_busy_align 1 Output When the wide bus interface is enabled and in 2X clock mode, indicates that the DDR3 Controller is busy and is not accepting new requests.

ddr_int_addr 34 Input Address bus containing row, column, and bank information.

ddr_int_burst_size 8 Input Indicates burst size of given read/write request. Valid ranges of this value are: 8’d4 8’d252 (multiples of 4) for DDR3

ddr_int_wr_request 1 Input Write request.

ddr_int_wrdata_req 9 Output

Request by DDR Controller for data to be written to the DDR Memory. This is asserted some number of clock cycles after a write request, and is burst length number of clock cycles in length per write request.

ddr_int_wrdata_req_early 9 Output Early request by DDR controller for data to be written to the DDR memory. Signal will be asserted earlier then ‘ddr_int_wrdata_req’ which can be used.

ddr_int_wrdata_req_align 9 Output

When the wide bus interface is enabled and in 2X Clock mode, request by DDR Controller for data to be written to the DDR Memory. This signal bus essentially performs a single alignment function but is provided as a multi-bit signal for timing purposes.

ddr_int_wrdata_req_early_align 9 Output

When the wide bus interface is enabled and in 2X Clock mode, early request by DDR Controller for data to be written to the DDR Memory. Signal will be asserted earlier then ‘ddr_int_wrdata_req_align’ which can be used. This signal bus essentially performs a single alignment function but is provided as a multi-bit signal for timing purposes.

ddr_int_wrdata [SIZE*4-

1:0] Input

Data to be written to the DDR Memory. This data is provided two cycles after ddr_int_wrdata_req is asserted. SIZE: 72, 64, 32, 16, 8. When the wide bus interface is enabled, the SIZE parameters and consequently the bus width, are doubled.

ddr_int_wrdata_mask [SIZE/2-

1:0] Input

Data mask corresponding to “ddr_int_wrdata”. When any data mask bit is asserted, the data contained in the corresponding ‘ddr_int_wrdata’ byte will not be written to Memory. SIZE: 72, 64, 32, 16, 8. When the wide bus interface is

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enabled, the SIZE parameters and consequently the bus width, are doubled.

ddr_int_rd_request 1 Input Read request.

ddr_int_rddata [SIZE*4-

1:0] Output

Data read back from the DDR Memory in response to a read request. SIZE: 72, 64, 32, 16, 8. When the wide bus interface is enabled, the SIZE parameters and consequently the bus width, are doubled.

ddr_int_rddata_valid 9 Output Valid signal corresponding to read data (‘ddr_int_rddata’).

ddr_int_rddata_valid_early 9 Output Early valid signal corresponding to read data (‘ddr_int_rddata’)

ddr_int_rddata_valid_align 9 Output When the wide bus interface is enabled and in 2X clock mode, valid signal corresponding to read data (‘ddr_int_rddata’)

ddr_int_rddata_valid_early_align 9 Output When the wide bus interface is enabled and in 2X clock mode, early valid signal corresponding to read data (‘ddr_int_rddata’)

ddr_int_cmd_auto_pch 1 Input Core can send a Auto pre charge request to controller

ddr_int_cmd_power_down 2 Input Core can send a power down request to controller. Each signal [1:0] controls each SDRAM on its chip select.

ddr_int_cmd_ref_req 1 Input User-initiated refresh control. Core can send a refresh request to controller (manual control).

ddr_int_ref_ack 1 Output Refresh acknowledgement from controller to core

ddr_int_cmd_self_referesh 2 Input

Self refresh control. Causes the DDR3 SDRAM Controller Core to put the SDRAM into self refresh mode at the next refresh event. Each signal [1:0] controls each SDRAM on its chip select.

ddr_int_cmd_zq_cal_req 2 Input User initialized ZQ calibration. User can initiate ZQ calibration at next available opportunity. Each signal [1:0] controls each SDRAM on its chip select.

ddr_int_zq_cal_ack 1 Output ZQ calibrations acknowledge. Asserted for one clock when ZQ calibration command is issued to memory devices.

ddr_int_wrdata_valid 1 Output Frames the active data being written to SDRAM. Mimics ‘ddr_int_wrdata_req’ except it is delayed by one clock.

ddr_int_phy_ci_slave_adj 8 input ddr_int_phy_ci_slave_dqsn_en 9 Input *based on data width ddr_int_phy_co_wr_lvl_out 9 Output *based on data width

ddr_int_init_ack 1 Output Asserts for one clock to acknowledge init_refresh, init_precharge_all, init_mr, init_zq_cal, and init_wlvl_mrX_req. **

ddr_int_init_wlvl_done 1 Output Indicates completion of write leveling

status_wlvl_tap_value 9 Output Delay line value determined by write leveling calibration inside DDR3 controller. The value on this port corresponds to the DQS lane selected by ‘**’ parameter **

wlvl_active 1 Output Indicates that controller-driven automatic write leveling is in progress.

Table-1: Internal interface signals

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External (off-chip) Interface The External DDR interface signals (off-chip) from the DDR PHY to the external memory devices are shown in Table 2 below.

Signal Name Bus

Width Direction Description

sd_clk_p 4 Output SDRAM clock signal sd_clk_n 4 Output SDRAM clock signal sd_cke 4 Output SDRAM clock enable control signal sd_odt 4 Output SDRAM on die termination control signal sd_ras_n 1 Output SDRAM RAS control signal sd_cas_n 1 Output SDRAM CAS control signal sd_we_n 1 Output SDRAM write enable control signal sd_reset_n 1 Output SDRAM reset signal sd_a 16 Output SDRAM address bus sd_ba 3 Output SDRAM bank select sd_cs_n 4 Output SDRAM chip select sd_dm 9 Output SDRAM data mask sd_dummy 9 Output Internal use only. Leave unconnected sd_dq 72 Inout SDRAM data bus sd_dqsn 9 Inout SDRAM DQS bus, which is used to clock DQ bus sd_dqsp 9 Inout SDRAM DQS bus, which is used to clock DQ bus

Table-2: PHY/DDR controller to memory interface signals

Parameters

Parameters that can be set for both the DDR controller and PHY are shown in Table 3 below.

Parameter Default Value (hex)

Valid Values Description

DSIZE 72 Multiples of 8 from 8-72 Local side data width NUM_CLK_OUTS 3 1 to 4 Number of clock outputs

CONTROLLER_REFRESH_EN 1'h1 0-1

Enable controller initiated refreshes. 0: Embedded DDR Controller automatically handles cyclic autorefreshing of memory. 1: User manually overrides autorefresh control of memory.

DELAY_ACTIVATE_TO_PRECHARGE 5'h14 4-30 clock cycles Minimum ACTIVE to PRECHARGE

DELAY_ACTIVATE_TO_RW 4'h7 2-12 clock cycles Minimum time between ACTIVATE and READ/WRITE

DELAY_ACTIVATE_TO_ACTIVATE_DIFF_BANK 3'h4 2-6 clock cycles Minimum time between ACTIVATE to ACTIVATE in different banks

DELAY_PRECHARGE_TO_ACTIVATE 4'h7 1-12 clock cycles Minimum PRECHARGE to ACTIVATE.

DELAY_ACTIVATE_TO_ACTIVATE_SAME_BANK 6'h20 5-42 clock cycles

Minimum ACTIVATE to ACTIVATE/AUTO-REFRESH in same bank

BANK_ACTIVATE_PERIOD 6'h20 7-32 clock cycles Four bank activate period

DELAY_AUTO_REFRESH_TO_ACTIVATE_SAME_BANK 9'h03B 6-511 clock cylces Minimum AUTO-REFRESH to ACTIVATE/AUTO-REFRESH in same

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bank

DELAY_READ_TO_PRECHARGE 3'h4 4-6 clock cycles Minimum Read to precharge (DDR3 only)

DELAY_WRITE_TO_PRECHARGE 4'h8 5-12 clock cycles Minimum time from write to PRECHARGE

DELAY_WRITE_TO_READ 3'h4 2-6 clock cycles Minimum time from write to read. DELAY_READ_TO_WRITE 3'h3 1-7 clock cycles Read to write delay (valid values: 1

DELAY_WRITE_TO_WRITE_DIFF_BANK 3'h2 0-7 clock cycles Minimum delay from write to write (different ranks)

DELAY_WRITE_TO_READ_DIFF_BANK 3'h1 0-7 clock cycles Minimum delay from write to read (different ranks)

DELAY_READ_TO_READ_DIFF_BANK 3'h2 1-7 clock cycles Minimum delay from read to read (different ranks)

DELAY_ADDITIVE_DDR3_LATENCY 3'h0 0-5 clock cycles Additive latency value (DDR2) CAS_LATENCY 4'h7 5-11 Cas latency CAS_WRITE LATENCY 4'h6 5-8 Cas Write latency

DELAY_LOADMODE_TO_ACTIVATE 3’h6 clock cycles Minimum LOADMODE to ACTIVATE command

DELAY_LOADMODE_TO_ANY 4’hE clock cycles Minimum LOADMODE to ANY command

DELAY_SELF_REFRESH_TO_NON_DLL_CMD 9'h040 clock cycles Minimum time from self refresh to non-DLL command

DELAY_SELF_REFRESH_TO_NON_READ_CMD 8'h87 clock cycles Minimum time from self refresh to non-read command

DELAY_RESET_HIGH_TO_CLK_HIGH 9'h040 clock cycles Minimum delay from memory reset high to cke hig

REFRESH_PERIOD 16'h07D0 10-65535 refresh time

interval / tCK Refresh period. This is the number of clock cycles between refresh commands.

DELAY_STARTUP 19'h000c8 10-524287 clock cycles Initialization delay after reset

NUM_COLUMN_BITS 3'h5 5, 6, 7

Number of column bits 5: 10 column bits 6: 11 column bits 7: 12 column bits

NUM_ROW_BITS 3'h3 2, 3, 4, 5

Number of row bits 2: 13 row bits 3: 14 row bits 4: 15 row bits 5: 16 row bits

NUM_BANK_BITS 1'h1 0, 1

Number of bank bits 0: 2 bank bits 1: 3 bank bits

REGISTERED_DIMM 1'h0 0,1

Registered dimm support 0: UDimm 1: RDimm

ODT_READ_CS0 8'h00

Each bank contains 8 bits, one per DQ. ODT is enabled when set to 1

On die termination selection for reads on cs0

ODT_READ_CS1 8'h00



ODT_READ_CS2 8'h00



ODT_READ_CS3 8'h00



ODT_READ_CS4 8’h00

Each bank contains 8 bits, one per DQ. ODT

is enabled when set to 1 On die termination selection for reads on cs4







ODT_READ_CS7 8’h00 Each bank contains 8

bits, one per DQ. ODT On die termination selection for reads on cs7

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is enabled when set to 1

ODT_WRITE_CS0 8'h01


On die termination selection for writes on cs0

ODT_WRITE_CS1 8'h02



ODT_WRITE_CS2 8'h04



ODT_WRITE_CS3 8'h08



ODT_WRITE_CS4 8’h10


is enabled when set to 1 On die termination selection for writes on cs4










READ_EN_DELAY_LANE 3’h5 0-5 Adjusts the delay of the read data out of the PHY

BYPASS_TXRX_SD 0 0 or 1

0 1X clock mode. Core run at same speed as controller 1 2X clock mode. Core run at half the speed of controller.

If no soft write leveling or read leveling is used, then use these parameters: BYTE_LANE*_DLL_ADJ_DQ (2) 6’h4 DQ Slave adjust for Byte Lane * BYTE_LANE*_DLL_ADJ_DQS (2) 6’h16 DQS Slave adjust for Byte Lane * BYTE_LANE*_DLL_ADJ_DP (2) 6’h6 DP Slave adjust for Byte Lane *

BYTE_LANE*_WR_LVL_DQ_SELECT (2) 4’b0000 Which DQ bit is used for write leveling *

BYTE_LANE_DLL_MADJ 8’h2a Master adjust BYTE_LANE_DLL_DQSX9_CLK_ADJ 8’h3f Slave adjust for DQSX9 BYTE_LANE_CAC_DLL_ADJ_DQSN 6’h17 Slave adjust for address bytes lanes

Table-3: Parameter values of the DDR controller

Notes on Table 3: 1. These parameters are available for all byte lanes. For example if we have 64 DQ bits that will be 8 byte

lane. So these parameters are available for all 8 lanes, replace the * with each byte number.

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Address Mapping

The Speedster22i DDR controller contains a specific address bus mapping which is broken down as follows:

• Column [colbits-1:0]

• Bank [bankbits-1:0]

• Row [rowbits-1:0]

• Chip Select (encoded) [3:0]

The exact bit positions of the mapping will vary depending on the values of the configuration parameters denoted ‘colbits,’ ‘rowbits,’ and ‘bankbits.’

BankRow

lsbmsb

bankbits colbitsrowbitsddr_int_addr[33:0] CS[3:0]leading 0s (if req’d)

Chip Select

Figure 3: Address mapping of ‘ddr_int_addr’ Signal

The configuration parameters relating to memory size (in terms of numbers of columns, banks and rows) are defined by the user in the DDR Control Logic instantiation. Valid ranges of these values are give in the “Parameters” section above.

Speedster22i devices supports four ranks per DDR control block (two dual-rank DIMM or one quad-rank DIMM per controller). This corresponds to four chip selects: CS [3:0] = {CS3, CS2, CS1, CS0}.

In configurations where the number of column bits, row bits, bank bits and 4 chip select bits do not add up to the total 34 bit length of ‘ddr_int_addr ,’ the upper most bits of ‘ddr_int_addr [33:0]’ are ignored, and should be filled with zeros.

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Write Interface Details

The Speedster22i DDR controller contains a simple write interface to the DDR Driver logic..

This uses a 2X clock mode - the DDR driving logic (user RTL implemented in the FPGA fabric) runs at half the frequency of DDR controller. The DDR controller/PHY outputs a Clock (‘clk_div2’), which the user must use to drive write data and latch read data. For example, a 1866Mbps data rate required the DDR controller and PHY to operate at 1066MHz, but the 2X mode allows the internal interface to the fabric to operate at 533MHz. If 2X mode is not used, the highest off chip data rate available is 1066Mbps.

In 2X mode, the core interface signals remain the same except for (‘ddr_int_busy’, ddr_int_wrdata_req’, ’ddr_int_wrdata_req_early’, ‘ddr_int_rddata_valid’, ‘ddr_int_rddata_valid_early’). Instead of the above signals, users must interface with the following signals (‘ddr_int_busy_align’, ddr_int_wrdata_req_align’, ’ddr_int_wrdata_req_early_align’, ‘ddr_int_rddata_valid_align’, ‘ddr_int_rddata_valid_early_align’).

The DDR driver logic (user RTL) provides a write request (‘ddr_int_wr_request’) along with a corresponding address (‘ddr_int_addr’) and burst length (‘ddr_int_burst_size’).

This logic then needs to provide data (‘ddr_int_wrdata’) 2 clock cycles after a data request (‘ddr_int_wrdata_req_early_align’) is received from the Speedster22i DDR Controller. The logic can also use (‘ddr_int_wrdata_req_align’). The ‘ddr_int_wrdata [287:0]’ signal represents the data to be written to the memory over four sequential DDR clock edges (72 bits at a time). The data contained in ‘ddr_int_wrdata [71:0]’ is written to the specified column address, and that contained in ‘ddr_int_wrdata [143:72]’ is written to the specified column address + 1. Data from ‘ddr_int_wrdata [215:144]’ will be written to specified column address+2 and data from ‘ddr_int_wrdata [287:216]’ will be written to specified column address+3.

The write requests are subject to the controller being busy (‘ddr_int_busy_align’).

The DDR controller supports burst length option BL8. Each burst will contain 2 local side transfers, which is equivalent to 8 transfers to the DDR memory.

Figure 4: Write Interface 2X Clock Mode

Speedster22i DDR

Controller

DDR Interface Logic

(User RTL)

ddr_int_wr_request

ddr_int_busy_align

ddr_int_addr[33:0]

ddr_int_wrdata_req_alignddr_int_wrdata[287:0]


ddr_int_writedata_mask[17:0]

ddr_int_wrdata_req_early_align

Clk_div2

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The following timing diagram illustrates a single write command of burst length 4. The signals shown in the following diagrams are ports at the (‘ddr3_xSIZE1_LOCATION2’. Where 1: SIZE = 72, 64, 32, 16, 8 and 2: LOCATION=EN, EC, ES, WN, WC, WS).

Figure 5: Internal Interface Write Protocol Timing Diagram

This 2-cycles delay between the ‘ddr_int_wrdata_req_early_align’ and ‘ddr_int_wrdata [287:0]’ is optional. This is implemented using a parameter ‘addrcmd_delay’ value setting to “4’h9”. This extra cycle provides an advantage to the user to latch the data to be written to the PHY. This implementation is optional to the user. If the user wants to use 1-cycle delay between ‘ddr_int_wrdata_req_early_align’ and ‘ddr_int_wrdata [287:0]’, in this case let keep the default value of the parameter ‘addrcmd_delay’. The default values for this parameter ‘addrcmd_delay’ is “4’h8”. The user needs to be very careful about their implementation while using Achronix DDR-controller implementing 1-cycle delay implementation for latching the write-data to be written to PHY. For the 2-cycle delay, the user has enough time to latch the data.

The diagram above shows the signals between the FPGA fabric core and DDR controller. (‘ddr_int_wrdata_req_early_align’) signal is 3 cycles earlier then (‘ddr_int_wrdata_req’) signal. The user can use ‘ddr_int_wrdata_req_early_align’ signal to be ready to write the data and at the assertion of ‘ddr_int_wrdata_req’ signal to drive user data on ‘ddr_int_wrdata’.

clk_div2

ddr_int_wr_request

ddr_int_addr[33:0]

ddr_int_busy

d0 d1 d0 d1ddr_int_wrdata [143:0]

Timing relationship between ddr_int_wr_request assertion and ddr_int_wrdata_req_early assertion based on AL/CL configuration settings, refresh status and status on bank/

row being accessed

ddr_int_wrdata_req_early

Present data 3-cycles after ddr_int_wrdata_req_early is

asserted

16 UG031, Nov 18, 2014

ddr_int_ wrdata_req_early_align

Clk_div2

ddr_int_wr_ request

a0ddr_int_addr[33:0]

ddr_int_busy_align

ddr_int_ wrdata_req

ddr_int_ wrdata[287:0]

Valid Write commands

ddr_int_burst_size[7:0] 4

d0 d1

Timing relationship between ddr_int_wr_request assertion and ddr_int_wrdata_req assertion between AL/CWL configurations settings/refresh

status, and status of bank/row being accessed

Present data 1 cycle after ddr_int_wrdata_req_early_align is asserted

Figure 6: Internal Interface Write Protocol Timing Diagram with default value ‘addrcmd_delay’ to 8

This logic then needs to provide data (‘ddr_int_wrdata’) 1 clock cycles after a data request (‘ddr_int_wrdata_req_early_align’) is received from the Speedster22i DDR Controller. The logic can also use (‘ddr_int_wrdata_req_align’). The ‘ddr_int_wrdata [287:0]’ signal represents the data to be written to the memory over four sequential DDR clock edges (72 bits at a time). The data contained in ‘ddr_int_wrdata [71:0]’ is written to the specified column address, and that contained in ‘ddr_int_wrdata [143:72]’ is written to the specified column address + 1. Data from ‘ddr_int_wrdata [215:144]’ will be written to specified column address+2 and data from ‘ddr_int_wrdata [287:216]’ will be written to specified column address+3.



The diagram above shows the signals between the FPGA fabric core and DDR controller. (‘ddr_int_wrdata_req_early_align’) signal is 3 cycles earlier then (‘ddr_int_wrdata_req’) signal. The user can use ‘ddr_int_wrdata_req_early_align’ signal to be ready to write the data and at the assertion of ‘ddr_int_wrdata_req’ signal to drive user data on ‘ddr_int_wrdata’.

UG031, Nov 18, 2014 17

Figure 7: Write Protocol Timing Diagram (SDRAM Interface)

To request a write data transaction, the DDR driver logic (user RTL) must assert ‘ddr_int_wr_request’ along with a corresponding address (‘ddr_int_addr [33:0]’) and burst length (‘ddr_int_burst_size’).

A valid write request (ie. one which is successfully posted to the Speedster22i DDR Controller and propagated to the DDR Memory) is one in which ALL of the following conditions are met:

• ‘ddr_int_wr_request’ is asserted (active high)

• ‘ddr_int_addr [33:0]’ is driven

• ‘ddr_int_burst_size [7:0]’ is driven to a valid value for the given protocol

o 8’d4 8’d252 for DDR3 (multiple of 4)

• ‘ddr_int_busy_align’ is not asserted (active high)

• Latency of the DDR-controller provided data (ddr_int_wrdata) to the external memory is 4-cycle.

clock

Command

sd_ras_n

sd_cas_n

Notes: For case shown, DELAY_ACTIVATE_TO_RW = 5, CAS WRITE LATENCY =6, DELAY_ADDITIVE_DDR3_LATENCY=0

d0r d0f d1r d1f d2r d2f d3r d3f

ACT WR

sd_we_n

sd_a

sd_ba

sd_cs_n

sd_dq

sd_dm

sd_dqs

ROW COL

BANK BANK

CHIP CHIP

18 UG031, Nov 18, 2014

Back-to-Back Write Protocol 2X Clock Mode The following timing diagram (Figure 8) illustrates the same three cascaded, back-to-back write commands. Each valid write request (and corresponding data) is highlighted in a different color. For back-to-back write there are 5 clock-cycles gap required between the write requests. This is done with respect to 2X clock mode.

Figure 8: Write Protocol Timing Diagram (Write requests with valid writes highlighted)

a0 a1 a2

Valid Write commands after 5 cycles

clk_div2

ddr_int_wr_request

ddr_int_addr[33:0]

ddr_int_busy

ddr_int_wrdata_req

ddr_int_burst_size [7:0]

...

...

...

...

4

ddr_int_wrdata [287:0]

UG031, Nov 18, 2014 19

...

...

Timing relationship between ddr_int_wr_request assertion and ddr_int_wrdata_req_early assertion based on AL/CL

configuration settings, refresh status and status on bank/row being accessed

...

ddr_int_addr[33:0]

ddr_int_wr_request

clk_div2

ddr_int_busy

ddr_int_wrdata_req_early

ddr_int_wrdata[143:0] d0 d1 d0 d1

...

Present data 3-cycles after ddr_int_wrdata_req_early is

asserted

Figure 9: Write Protocol Timing Diagram (ddr_int_wrdata_req corresponding to respective writes highlighted)

If a write request is not valid (ie. ‘ddr_int_busy’ and ‘ddr_int_wr_request’ are asserted simultaneously), ‘ddr_int_wr_request’, ddr_int_addr [33:0]’, and ‘ddr_int_burst_size [7:0]’ signal values must be latched until ‘ddr_int_busy’ is de-asserted and a valid write request (‘ddr_int_wr_request’)can be posted as shown in Figure 8. There should be 5-cycles delay between the back-to-back ‘ddr_int_wr_request’ signal as shown in Figure 8. Corresponding ‘ddr_int_wrdata_req’ and ‘ddr_int_wrdata’ timing is shown in Figure 9.

The ‘ddr_int_wr_request’ signal may remain asserted for any number (with 5-cycles apart always) to generate any number of follow-on writes transactions (in cascaded bursts).

The data request (‘ddr_int_wrdata_req’) signal will be asserted two cycles prior to when the DDR driver logic (user RTL) must present data at the ‘ddr_int_wrdata’ bus and mask information at the ‘ddr_int_writedata_mask’ bus.

The Speedster22i DDR Controller will ensure that the ‘ddr_int_wrdata_req_early’ signal is asserted for the correct number of cycles (based on the ‘ddr_int_burst_size’ value specified for the corresponding write request) as well as at the correct time (in accordance with DDR latency requirements based on user-specified values of AL and CL parameters in the case of DDR/DDR2, or AL and CWL parameters in the case of DDR3).

The burst length (‘ddr_int_burst_size’) corresponding to a single given write request must be set to a valid value based on the given DDR protocol. For DDR3 has a range of 8’d4 to 8’d252. Note that the ‘ddr_int_burst_size’ value translates directly to the number of cycles for which ‘ddr_int_wrdata_req’ is asserted.

While bank and row addresses are derived directly from the address provided by the user (ie. DDR driver logic) for a given write request, the column address is incremented automatically within the Speedster22i DDR Controller for a given burst, starting with the

20 UG031, Nov 18, 2014

column address provided by the user for the given write request. For DDR3, since ‘ddr_int_burst_size’ is set as a multiple of 4, the user should always provide a column address with a modulo-8 value.

The ‘ddr_int_wrdata [287:0]’ signal represents the data to be written to the memory over two sequential DDR clock edges (144 bits at a time). The data contained in ‘ddr_int_wrdata [71:0]’ is written to the specified column address, that contained in ‘ddr_int_wrdata [143:72]’ is written to the specified column address + 1, that contained in ‘ddr_int_wrdata [215:144]’ is written to the specified column address + 2, and that contained in ‘ddr_int_wrdata [287:216]’ is written to the specified column address + 3.

The ‘ddr_int_writedata_mask [17:0]’ represents the data mask. Each bit within this bus corresponds to 8bits of the ‘ddr_int_wrdata [287:0]’ signal bus. Asserting a given bit within the ‘ddr_int_writedata_mask’ bus ensures that the corresponding 8 bits of the ‘ddr_int_wrdata’ bus do NOT get written to memory, overwriting its previous contents.

Write Protocol with Wide Bus Interface Enabled The DDR macro for Speedster22i Devices also provides users the option to ‘Enable a Wide Bus Interface’ through a checkbox control. In this mode, the DDR driving logic (user RTL implemented in the FPGA fabric) runs at one quarter the frequency of the DDR controller. This enabled FPGA fabric core timing to be met more easily, especially for high off-chip data rates. The DDR controller/PHY outputs a clock (‘clk_div4’), which the user must use to drive write data and latch read data. With a 1866Mbps data rate at the DDR controller, corresponding to the PHY operating at 1066MHz, enabling the wide bus interface ensures that the interface in the fabric can operate at 266MHz. The wide bus interface can be enabled for any and all modes and data rates.

When the wide bus interface is enabled, the core interface signals remain almost exactly the same as those required in the 2X clock mode. The only differences are that a new clock (‘clk_div4’) need be used, and the data and mask bus widths effectively double.

The DDR driver logic (user RTL) provides a write request (‘ddr_int_wr_request’) along with a corresponding address (‘ddr_int_addr’) and burst length (‘ddr_int_burst_size’).

This logic then needs to provide data (‘ddr_int_wrdata’) 1 clock cycle after a data request (‘ddr_int_wrdata_req_early_align’) is received from the Speedster22i DDR Controller. The logic can also use (‘ddr_int_wrdata_req_align’). The ‘ddr_int_wrdata [575:0]’ signal represents the data to be written to the memory over eight sequential DDR clock edges (72 bits at a time). The data contained in ‘ddr_int_wrdata [71:0]’ is written to the specified column address, and that contained in ‘ddr_int_wrdata [143:72]’ is written to the specified column address+1. Data from ‘ddr_int_wrdata [215:144]’ will be written to specified column address+2 and data from ‘ddr_int_wrdata [287:216]’ will be written to specified column address+3. Similarly, data contained in ‘ddr_int_wrdata [359:288]’ is written to the specified column address+4, and that contained in ‘ddr_int_wrdata [431:360]’ is written to the specified column address+5. Data from ‘ddr_int_wrdata [503:432]’ will be written to specified column address+6 and data from ‘ddr_int_wrdata [575:504]’ will be written to specified column address+7.


The DDR controller supports burst length option BL8. Each burst will contain a single local side transfers, which is equivalent to 8 transfers to the DDR memory.

UG031, Nov 18, 2014 21

DDR Interface Logic

(User RTL)

Speedster22i DDR

Controller

ddr_int_wr_request

ddr_int_addr[33:0]


ddr_int_busy_align

ddr_int_wrdata_req_early_align

ddr_int_wrdata_req_align

ddr_int_wrdata[575:0]

ddr_int_writedata_mask[35:0]

clk_div4

Figure 10: Write Interface with Wide Bus Interface Enabled

The following timing diagram illustrates a single write command of burst length 4. The signals shown in the following diagrams are ports at the (‘ddr3_xSIZE1_LOCATION2’. Where 1: SIZE = 72, 64, 32, 16, 8 and 2: LOCATION=EN, EC, ES, WN, WC, WS).

ddr_int_ wrdata_req_early_align

Clk_div4

ddr_int_wr_ request

a0ddr_int_addr[33:0]

ddr_int_busy_align

ddr_int_ wrdata_req

ddr_int_ wrdata[575:0]

Valid Write commands

ddr_int_burst_size[7:0] 4

d0

Timing relationship between ddr_int_wr_request assertion and ddr_int_wrdata_req assertion between AL/CWL configurations settings/refresh

status, and status of bank/row being accessed

Present data 1 cycle after ddr_int_wrdata_req_early_align is asserted

Figure 11: Internal Interface Write Protocol Timing Diagram with Wide Bus Interface Enabled

22 UG031, Nov 18, 2014

As shown above, the wrdata_req signal needs to be asserted for one clock cycle, and in the subsequent clock cycle the write data [575:0] is provided. The timing relationships with the SDRAM interface are essentially equivalent to the 2X Clock Mode interface.

A valid write request (ie. one which is successfully posted to the Speedster22i DDR Controller and propagated to the DDR Memory) is one in which ALL of the following conditions are met:

• ‘ddr_int_wr_request’ is asserted (active high)





• Latency of the DDR-controller provided data (ddr_int_wrdata) to the external memory is 8-cycle.

Read Interface Details

The Speedster22i DDR Controller contains a very simple read interface to the DDR Driver logic.

2X Clock mode must always be used. When using 2X clock mode DDR drive (user) logic in core runs at half the frequency of DDR controller. The DDR controller/PHY outputs a Clock (‘clk_div2’), which the user must use to drive write data and latch read data.

The core interface signals remain the same except for (‘ddr_int_busy’, ddr_int_wrdata_req’, ’ddr_int_wrdata_req_early’, ‘ddr_int_rddata_valid’, ‘ddr_int_rddata_valid_early’). Instead, the DDR driver (user) logic needs to use (‘ddr_int_busy_align’, ‘ddr_int_wrdata_req_align’, ’ddr_int_wrdata_req_early_align’, ‘ddr_int_rddata_valid_align’, ‘ddr_int_rddata_valid_early_align’).

The DDR driver (user) logic must provide a read request (‘ddr_int_rd_request’) along with a corresponding address (‘ddr_int_addr’) and burst length (‘ddr_int_burst_size’).

Speedster22i DDR controller provides valid signal for data to be read. This valid signal is ‘ddr_int_rddata_valid_align’. After assertion of ‘ddr_int_rddata_valid_align’, 2 cycles later, the DDR driver logic receives read data (‘ddr_int_rddata [287:0]’) from the Speedster22i DDR controller. The ‘ddr_int_rddata [287:0]’ signal represents the data read from the memory over four sequential DDR clock edges (72 bits at a time). The data contained in ‘ddr_int_rddata [71:0]’ is read from the specified column address, and that contained in ‘ddr_int_rddata [143:72]’ is read from the specified column address + 1. Data from ‘ddr_int_rddata [215:144]’ is read from specified column address+2 and data from ‘ddr_int_rddata [287:216]’ is read from specified column address+3.

The read requests are subject to the controller being busy (‘ddr_int_busy_align’).


UG031, Nov 18, 2014 23

Figure 12: Read Interface 2X Clock Mode

The following timing diagram illustrates a single read command of burst length 4. The signals shown in the following diagrams are ports at the (‘ddr3_xSIZE1_LOCATION2’. Where 1: SIZE = 72, 64, 32, 16, 8 and 2: LOCATION=EN, EC, ES, WN, WC, WS).

Figure 13: Internal Interface Read Protocol Timing Diagram

ddr_int_rd_request

ddr_int_busy_align

ddr_int_addr[33:0]

ddr_int_rddata_valid_alignddr_int_rddata[287:0]

Speedster22i DDR

Controller

DDR Driver Logic

(in Core Fabric)


ddr_int_rddata_valid_early_align

clk_div2

clk_div2

ddr_int_rd_ request

a 0ddr_int_addr[33:0]

ddr_int_busy_align

d0 d1

ddr_int_ rddata_valid_align

ddr_int_ rddata[287:0]

Valid Read Command

4ddr_int_burst_size[7:0]

Timing relationship between ddr_int_rd_request and ddr_int_rddata_valid assertion based on AL/CL configuration

settings, refresh status and status of bank/row begins assessed

24 UG031, Nov 18, 2014

The Corresponding external (off-chip) interface timing signals are shown in the Figure 14 below.

Figure 14: External Interface Read Protocol Timing Diagram

To request a read data transaction, the DDR driver (user) logic must assert ‘ddr_int_rd_request’ along with a corresponding address (‘ddr_int_addr [33:0]’) and burst length (‘ddr_int_burst_size’).

A valid read request (ie. one which is successfully posted to the Speedster22i DDR controller and propagated to the DDR Memory) is one in which ALL of the following conditions are met:

• ‘ddr_int_rd_request’ is asserted (active high)





Back-to-Back Read Protocol 2X Clock Mode The 1st word is provided on (‘ddr_int_rddata [143:0]’) 4 cycles after (‘ddr_int_rddata_valid’) is received from the Speedster22i DDR controller.

The following timing diagrams illustrate two cascaded, back-to-back read commands. Each valid read request (and corresponding data) is highlighted in a different color. The testing is done with respect to 2X-clock mode.

clock

Command

sd_ras_n

sd_cas_n

Notes: For case shown, DELAY_ACTIVATE_TO_RW = 5, CAS LATENCY =7, DELAY_ADDITIVE_DDR3_LATENCY=0

d0r d0f d1r d1f d2r d2f d3r d3f

ACT RD

sd_we_n

sd_a

sd_ba

sd_cs_n

sd_dq

sd_dm

sd_dqs

ROW COL

BANK BANK

CHIP CHIP

UG031, Nov 18, 2014 25

a0 a1 a2

Valid Write commands after 5 cycles

clock

ddr_int_rd_request

ddr_int_addr[33:0]

ddr_int_busy

ddr_int_rddata_valid

ddr_int_burst_size [7:0]

...

...

...

...

4

ddr_int_rddata [287:0]

Figure 15: Read Protocol Timing Diagram (with valid read request highlighted)

Timing relationship between ddr_int_rd_request assertion and ddr_int_wrdata_req_early assertion based on AL/CL configuration

settings refresh status and status of bank/row being assessed.

d0 d1 d0 d1

clock

ddr_int_rd_req

ddr_int_addr[33:0]

ddr_int_busy

ddr_int_rddata_valid

ddr_int_rddata [287:0]

...

...

...

...

...

...

...

...

d0 d1

...

Figure 16: Read Protocol Timing Diagram (with ddr_int_rddata_valid highlighted)

If a read request is not valid (ie. ‘ddr_int_busy’ and ‘ddr_int_rd_request’ are asserted simultaneously), ‘ddr_int_rd_request’, ‘ddr_int_addr [33:0]’, and ‘ddr_int_burst_size [7:0]’ signal values must be latched until such time as ‘ddr_int_busy’ is de-asserted and a valid read request (‘ddr_int_rd_request’)can be posted as shown in Figure 15. There should be 5-clock cycle gap required for the back-to-back read request (‘ddr_int_rd_request’).

The ‘ddr_int_rd_request’ signal may remain asserted for any number (with 5-cycles apart always) of clock periods to generate any number of follow-on read transactions (in cascaded bursts).

The read data corresponding to a given read request is returned a deterministic number of clock cycles after the read request. This deterministic amount of time represents the round-

26 UG031, Nov 18, 2014

trip delay of accessing as well as actually reading from the memory address. The read data is accompanied by a valid signal, denoted ‘ddr_int_rddata_valid.’

The Speedster22i DDR Controller will ensure that the ‘ddr_int_rddata_valid’ signal is asserted for the correct number of cycles (based on the ‘ddr_int_burst_size’ value specified for the corresponding read request) as well as at the correct time (in accordance with DDR latency requirements based on user-specified values of AL and CL parameters and the total round-trip latency of the given memory access).

The burst length (‘ddr_int_burst_size’) corresponding to a single given read request must be set to a valid value based on the given DDR protocol. For DDR3 has a range of 8’d4 to 8’d252. Note that the ‘ddr_int_burst_size’ value translates directly to the number of cycles for which ‘ddr_int_rddata_valid’ is asserted.

As with writes, while bank and row addresses are derived directly from the address provided by the DDR driver (user) logic for a given read request, the column address is incremented automatically within the Speedster22i DDR Controller, starting with the column address provided by the user. For DDR3, since ‘ddr_int_burst_size’ is set as a multiple of 4, the user should always provide a column address with a modulo-8 value.

The ‘ddr_int_rddata [287:0]’ signal represents the data read from the memory over two sequential DDR clock edges (144 bits at a time). The data contained in ‘ddr_int_rddata [71:0]’ is read from the specified column address, that contained in ‘ddr_int_rddata [143:72]’ is read from the specified column address + 1, that contained in ‘ddr_int_rddata [215:144]’ is read from the specified column address + 2, and that contained ‘ddr_int_rddata [287:216]’ is read from the specified column address + 3.

Read Protocol with Wide Bus Interface Enabled As mentioned earlier, the wide bus interface may be enabled for all data rates but is particularly useful at high data rates to ease the timing closure effort for logic in the FPGA fabric. When the wide bus interface is enabled, the DDR driver (user) logic in core runs at one quarter the frequency of the DDR controller. The DDR controller/PHY outputs a clock (‘clk_div4’), which the user must use to drive write data and latch read data.

The core interface signals are essentially exactly the same as those in 2X clock mode, except that the data and mask bus widths are doubled and all signals are aligned to the new clock (‘clk_div4’) provided by the DDR controller/PHY.

The DDR driver (user) logic must provide a read request (‘ddr_int_rd_request’) along with a corresponding address (‘ddr_int_addr’) and burst length (‘ddr_int_burst_size’).

Speedster22i DDR controller provides valid signal for data to be read. This valid signal is ‘ddr_int_rddata_valid_align’. After assertion of ‘ddr_int_rddata_valid_align’, 2 cycles later, the DDR driver logic receives read data (‘ddr_int_rddata [575:0]’) from the Speedster22i DDR controller. The ‘ddr_int_rddata [575:0]’ signal represents the data read from the memory over eight sequential DDR clock edges (72 bits at a time). The data contained in ‘ddr_int_rddata [71:0]’ is read from the specified column address, and that contained in ‘ddr_int_rddata [143:72]’ is read from the specified column address+1. Data from ‘ddr_int_rddata [215:144]’ is read from specified column address+2 and data from ‘ddr_int_rddata [287:216]’ is read from specified column address+3. Similarly, data contained in ‘ddr_int_rddata [359:288]’ is read from the specified column address+4, and that contained in ‘ddr_int_rddata [431:360]’ is read from the specified column address+5. Data from ‘ddr_int_rddata [503:432]’ is read from specified column address+6 and data from ‘ddr_int_rddata [575:504]’ is read from specified column address+7.

UG031, Nov 18, 2014 27

The read requests are subject to the controller being busy (‘ddr_int_busy_align’).

The DDR controller supports burst length option BL8. Each burst will contain a single local side transfer, which is equivalent to 8 transfers from the DDR memory.

Speedster22i DDR

Controller

ddr_int_rd_request

ddr_int_addr[33:0]


ddr_int_busy_align

ddr_int_rddata_valid_early_align

ddr_int_rddata_valid_align

ddr_int_rddata[575:0]

clk_div4

DDR Driver Logic

(in Core Fabric)

Figure 17: Read Interface with Wide Bus Interface Enabled

The following timing diagram illustrates a single read command of burst length 4. The signals shown in the following diagrams are ports at the (‘ddr3_xSIZE1_LOCATION2’. Where 1: SIZE = 72, 64, 32, 16, 8 and 2: LOCATION=EN, EC, ES, WN, WC, WS).

clk_div4

ddr_int_rd_ request

a 0ddr_int_addr[33:0]

ddr_int_busy_align

d0

ddr_int_ rddata_valid_align

ddr_int_ rddata[575:0]

Valid Read Command

4ddr_int_burst_size[7:0]

Timing relationship between ddr_int_rd_request and ddr_int_rddata_valid assertion based on AL/CL configuration

settings, refresh status and status of bank/row begins assessed

Figure 18: Internal Interface Read Protocol Timing Diagram with Wide Bus Interface Enabled

28 UG031, Nov 18, 2014

To request a read data transaction, the DDR driver (user) logic must assert ‘ddr_int_rd_request’ along with a corresponding address (‘ddr_int_addr [33:0]’) and burst length (‘ddr_int_burst_size’).

A valid read request (ie. one which is successfully posted to the Speedster22i DDR controller and propagated to the DDR Memory) is one in which ALL of the following conditions are met:

• ‘ddr_int_rd_request’ is asserted (active high)




o ‘ddr_int_busy_align’ is not asserted (active high)

UG031, Nov 18, 2014 29

Memory Interface Latency

Depending on the data rate and the mode (width) used, the write and read latency for the DDR3 controller will vary. Table 4 below provides detailed clock cycle counts for write and read latencies for each of these cases.

Mode Data-Rate Write-Latency (Clock Cycles)

Read-Latency (Clock Cycles)

1X Up to 1066 Mbps 6 8 2X Up to 1600 Mbps 6 9 2X From 1601 Mbps to 1866 Mbps 7 10

Wide-Bus Up to 1600 Mbps 8 11 Wide-Bus From 1601 Mbps to 1866 Mbps 9 12

Table-4: Latency Information for different memory controller modes

30 UG031, Nov 18, 2014

Customization using ACE

Figure 19 below shows the ACE interface which allows customization of the DDR macro. Users can configure the parameter settings according to their requirements and ACE will write out instantiatable RTL, as well as constraint files for use in an ACE project.

Figure 19: DDR3 Customization using ACE

After setting all parameter values, use the “Generate” button to write out the DDR macro for instantiating into your design.

UG031, Nov 18, 2014 31

Revision History

The following table shows the revision history for this document.

Date Version Revisions

3/29/2013 1.0 Initial Draft Document 4/15/2013 1.1 Corrected links. 10/7/14 2.0 Significant updates 11/18/14 2.1 Fix Labels/references to diagrams

32 UG031, Nov 18, 2014

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