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Designing LCD applications with NXP ARM Cortex-M3 LPC1788

Kenneth Dwyer, eeTimes Webinar, July 13th, 2011

Agenda

NXP and LPC1788 Introduction

LCD Terminology and Technologies

LCD Interface and signals

NXP Microcontrollers with LCD interface

System Issues to consider

LCD Software and Tools

3rd Party LCD Software Support

LPCZone and Training

Q&A

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NXP is a leader in ARM Flash MCUs

Clear strategy: 100% focus on ARM

Top performance through leading technology & architecture

Design flexibility through pin- and software-compatible solutions

– Scalable memory sizes– Widest range of peripherals

Unlimited choice through complete families for multiple cores

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NXP MCU – the only complete ARM range of Cortex-M0, Cortex-M3 and Cortex-M4 processors

NXP ARM Cortex-M Continuum

Cortex-M4Cortex-M3Cortex-M0

True 8/16-bit replacement

- low power, low cost, more performance

High performance for communication and

control- LCD, USB, Ethernet, CAN and much more

Advanced Digital Signal control

- Floating point unit- Dual-core options

$0.65* $7.00*

Over 250 different ARM based microcontrollers available!!

Entry levelCortex-M0

Fully featured Cortex-M4

(* Recommended price at 10kpcs)

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LPC178XBringing LCD graphics to Cortex-M3

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Bridging Cortex-M3 and ARM7

LPC1700 Cortex-M3 MCUs are pin-compatible to NXP ARM7 MCUs allowing easy project migration

– LPC178x is pin-compatible to the LPC247x series– LPC177x is pin-compatible to the LPC246x, LPC245x and LPC238x series– LPC176x is pin-compatible to the LPC236x series

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LPC178x series

Cortex-M3 performance @ 120MHz

Up to 96 kB on-chip SRAM

Up to 512 kB on-chip flash memory

First Cortex-M3 with full LCD graphics controller

Up to 4 kB on-chip EEPROM

See web: http://ics.nxp.com/products/lpc1000/lpc17xx/

Maximum bandwidth for USB and Ethernet

communication because of unique matrix bus and

flexible SRAM implementation

32-bit full External Memory Interface

New NXP USART with support for Smart Card

Interface

New NXP Event Recorder in RTC domain for anti-

tampering protection

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LPC177x & LPC178x Features

Analog Peripherals– 12-bit ADC with 8 channels (400 ksps)– 10-bit digital-to-analog converter

Other Peripherals– LCD controller (LPC178x)– Up to 32-bit External Memory Controller– Low Power Real-time clock– Event recorder– Eight-channel, general-purpose DMA– Up to 165 GPIO– Motor control PWM– Quadrature encoder interface– Four 32-bit timers/counters– 12 MHz internal RC oscillator trimmed to

1% accuracy

ARM Cortex-M3 Core– 120 MHz operation– Nested Vectored Interrupt Controller (NVIC)– Wakeup interrupt controller– Memory Protection Unit– CRC Calculation engine

Memories– Up to 512 kB Flash memory– Up to 96 kB SRAM (3 blocks)– Up to 4 kB EEPROM

Serial Peripherals– 10/100 Ethernet MAC– USB 2.0 full-speed device/host/OTG– Four UARTs + one USART– Two CAN 2.0B controllers– Three SSP/SPI controllers– Three I2C (one with FM+)– SD/MMC– I2S interface

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LPC178x

Four parts in the family support LCD

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HMI / Home-display

Target application for LPC177x / LPC178xNXP Cortex-M3 design-wins in multiple applications

Point-of-sale terminals

Car AlarmsPLC

And many other communicationsapplications, e.g.:

- Web server- Multi-protocol

bridge

And many other industrial/medical applications, e.g.:

- HVAC- security monitoring

- video intercom- circuit breakers

And many other consumer / appliance

applications, e.g.:- Audio

- Alarm systems- Scanners

- Small appliances

And many other transportation

applications, e.g.:- Aftermarket- GPS/Fleet

management

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LCD Terminology and Technologies

Resolution and Color Depth

Resolution is not measured in inches!– QVGA 320 X 240– VGA 640 x 480– SVGA 800 X 600– Landscape or portrait orientation

Color depth or bits per pixel (bpp)

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What is a Frame Buffer?

Contiguous memory buffer containing a complete frame of data

Consists of color values for every pixel– For QVGA with 16 bpp color => 240 x 320 x 2 = 150kB of RAM

Color values are commonly represented as– 1 bit (1 bpp): Monochrome– 2 bit (2 bpp): Palette based (4 colors)– 4 bit (4 bpp): Palette (16 colors, controller has a palette look-up table)– 8 bit (8 bpp): Palette (256 colors, controller has a palette look-up table)– 16 bit (16 bpp): High color format (5:5:5 - 32,768 colors; 5:6:5 - 65,536

colors)– 24 bit (24 bpp): True color format (16,777,216 colors)

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Palette Based Frame Buffer

The frame buffer will contain an index value for each pixel

Palette RAM is pre-filled with 16-bit color value for each index

NXP microcontrollers have 256 entries to support– 1, 2, 4, or 8 bpp palletized color displays for color STN and TFT– 1, 2, or 4 bits-per-pixel (bpp) palletized displays for mono STN

Framebuffer Palette Image

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LCD panel Technologies – STN and TFT

STN (Super-Twisted Nematic)– Slower response compared to TFT technologies– Lower cost and power than TFT– Variations include Color STN (CSTN) and Dual STN (DSTN)– STN displays only turn segments on and off

TFT (Thin-Film transistor)– Fast response– Higher cost than STN, Uses more power than STN– Variations include Advanced TFT (ADTFT) and Highly Reflective TFT

(HRTFT)

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LCD Clocked STN

R

R

R

G

G

G

B

B

B

R G B

R G B

R G B

R G B

R G B

320x240 CSTN display

Element 0,line 0

Element 959,line 0

Element 3,line 239

D0 D3D2D1

3 RGB elements make 1 pixel

With a 4-bit CSTN display, a clock of data will drive 4 elements, or 1-1/3 pixels. It will take 240 clocks to

drive all the data for a 320 pixel line.

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LCD Clocked TFT

320x240 TFT display

Pixel 0 (16 bits),line 0

Pixel 319,line 0

Pixel 1, line 239

With a 18-bit TFT display, a clock of data will drive 1 pixel. It will take 320 clocks to drive all the data for a

320 pixel line.

RGB RGB RGB

RGBRGB RGB

RGBRGB RGB

R5...R0 G5...G0 B5...B0

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LCD Interface and signals

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Driving a clocked LCD bus

Host MCU LCD panelData lines

VSYNC/FP

HSYNC/LP

Pixel clock

Constant current source

BacklightPWM

Refresh Rate

REFRESH_RATE (Hz) = pixel_clock_rate / [(vertical_resolution + vertical_front_porch +

vertical_back_porch) * (pixel_clocks_per_data_line + horizontal_front_porch + horizontal_back_porch))]

Example : – 6.5MHz pixel clock– vertical resolution=240 lines,– vertical front porch=5 lines, – vertical back porch=1 line, – pixel clocks per data line = 320 pixels,– horizontal front porch=20 clocks, – horizontal back porch=10 clocks

– REFRESH_RATE = 6,500,000 / [(240 + 5 + 1) * (320 + 20 + 10)] = 75.5Hz

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LCD Signals

The largest configuration for the LCD controller uses 31 pins. There are many variants using as few as 10 pins for a monochrome STN panel.

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LCD STN Signals

Single Panel

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LCD TFT Signals

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Driving the LCD – various timings

320x240 display shown with timing for VSYNC, HSYNC,

clock, and porch values

VSYNC starts the frame

Vertical back porch timing

Vertical front porch timing

Horizontal front porch timing

Horizontal back porch timing

HSYNC starts at the beginning of

each line

Truly 240 x 320 TFT RGB666

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Snapshot of incorrect LCD settings

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LCD – TFT Horizontal Timings

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LCD – TFT Vertical Timings

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NXP Microcontrollers with LCDinterfaces

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NXP Microcontrollers with LCD interfaces

Main features of the LCD Controller:– Support for STN Single and Dual and TFT panels– Up to 1024x768 resolution– 24-bit LCD interface supports 24bpp (16M colors)– Palette table allowing display of up to 256 of 64k colors– Adjustable LCD bus size supports various panel bus configurations– Dedicated LCD DMA controller– Hardware cursor support

In addition to the LPC1788 the following devices have the same interface:

– LPC1850, LPC4300, LPC325x, LPC247x and LH7 devices

This helps to significantly to reduce software porting efforts

Configuring the LPC1788 LCD

Power: In the PCONP register, set the PCLCD bit (0 @ Reset).– Note the LCD power-up sequence

Setup the clocks and timing registers

Select LCD pins and pin modes via the relevant IOCON registers

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Dual-CSTN data flow

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NXP Microcontrollers – TFT data flow

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System Issues to Consider

LPC178x bandwidth calculator

http://ics.nxp.com/support/documents/microcontrollers/xls/lpc178x.lcd.bus.load.calculator.xls

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LCD Tearing

Tearing:

– Result of LCD DMA unable to service the LCD FIFO in time– Use the FIFO Underflow to monitor for this

Workarounds– Change AHB priority – next slide– Slow down frame refresh rate, pixel clock if possible– Use 32-bit wide external memories– Increase the SDRAM clock speed, use faster SRAM– Profile code and move frequently accessed code to internal SRAM

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LPC1788 LCD AHB Priority

AHB Matrix Arbitration register (Matrix_Arb - 0x400F C188)

The values used for the various priorities are 3 = highest, 0 = lowest

To give priority to the LCD DMA use the value 0x0000 0C09

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LCD Software and Tools

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Basic Graphic’s Library - SWIM

A free ‘basic’ graphics library– Simple Windows Interface Manager– Basic fonts ASCII characters, 6x7, 6x13, 8x8– Draw boxes, lines, set colors – Display and scale bitmap images

AN10815– API documentation for SWIM Library– Quick start guide document– IAR, Keil, Rowley, GNU projects for:

• LPC3250 Phytec, LPC2478 and LPC1788 EA, LPC1850 Hitex

– http://ics.nxp.com/support/documents/microcontrollers/zip/an10815.zip

SWIM Code Overview

Using SWIM it’s easy to setup the LCD controller

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LPC Bitmap Converter Utility

This tool converts BMP format into C Code format

Useful for importing images but uses a lot of memory – not compressed like JPEG or GIF

Command line tool Windows 7 compatibility

Source code available

http://www.lpcware.com/content/nxpfile/bmp-c-image-conversion-utility

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LPC1788 Boards and IDE’sEvaluation Boards

Embedded Artists LPC1778/88 (OM13001) – Display panel separate

IAR KSDK-LPC1788

FDI uEZ-LPC1788

IDEs

LPCXpresso

ARM/Keil µVision4

CodeRed RedSuite

IAR Embedded Workbench for ARM (EWARM)

JTAG debuggers

All debuggers supporting Cortex-M3

Available Now!

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Other support material

http://ics.nxp.com/support/microcontrollers/lcd/

LPC178x PDL – Peripheral driver library– Software drivers and examples for all peripherals– Includes USB, Ethernet and LCD examples– CMSIS 2.0 Compliant– http://ics.nxp.com/support/documents/microcontrollers/?scope=LPC178x&t

ype=software&search=CMSIS

http://ics.nxp.com/literature/presentations/microcontrollers/pdf/graphics.lcd.technologies.pdf

uClinux Q3/2011 with all the graphics packages it offers – nano-X (formerly microWindows), Qte, directfb

BSDL, IBIS Models, Orcad symbols– http://ics.nxp.com/support/models/lpc1000/

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Touchscreen AN

AN10675– http://ics.nxp.com/support/documents/microcontrollers/pdf/an10675.pdf– Details on how to utilize the ADC for Touchscreen support– Technique can be easily adapted for other MCUs

LPC3250 has dedicated hardware support for resistive touchcreens

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Top plate

Bottom plate

X+ X-

Y+

Y-

VREF

Resistor which much higher impedance than

the touchscreen

To ADC1

To ADC2

GPIO1

GPIO2

GPIO3

GPIO4

LPC247x Design Example

This illustrates how to connect the following

– STN 4-bit B/W QVGA (320 X 240)– TFT 18-bit WVGA (800 X 480)– TFT QVGA (320 X 240)– ADTFT 24-bit QVGA (320 X 240)

http://ics.nxp.com/support/design/microcontrollers/lcd.controller/

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3rd party LCD Software Support

BlueWater Embedded Prism/Prism-Micro

Prism Micro is for lower color depth applications, <= 8bpp (256 colors)

It has a smaller footprint than Prism, but it is still C++ API

Demo software here:http://www.bwembedded.com/products/prism_target_demos.php

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FDI uEZGUI-1788 System

LPC1788 system running uEZ +FreeRTOS

Seiko 7.0” TFT WVGA 800x480 with integrated Touch Screen

Rowley Crossworks and JLINK

GPL licensed source code

http://www.teamfdi.com/products/uEZGUI-1788-70WVE/brochure/uEZGUI-1788-70WVE%20Brochure.pdf

http://sourceforge.net/projects/uez/

http://ics.nxp.com/support/microcontrollers/lcd/#Featured

Segger emWIN

Written in ANSI-C

Widgets, anti-aliasing, multiple fonts

Touchscreen support integrated

Virtual screen, VNC Support

Memory devices – smoother transitions

Full API Documentation

NXP evaluation versions here– http://www.segger.com/cms/nxp.html

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Other Third party offerings

I2ST– Java virtual machine– Support for LPC2478 and LPC1788– http://www.is2t.com

GHI– Microsoft .NET Micro Framework – FEZ support LPC1788 and LPC2478 devices– www.GHIElectronics.com

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LPCZone, Training

Where to get started?

www.nxp.com/microcontrollers– MCU homepage

www.nxp.com/lpczone– Product updates and training

www.nxp.com/lpcxpresso– Low-cost development

www.mbed.org– Rapid proto-typing

Introduction to NXP's Cortex-M0/M3/M4 processors – http://ics.nxp.com/support/training/cortex-m.intro/

LPC1000 debug tools, tips, and tricks (part 1) – http://ics.nxp.com/support/training/lpc1000.debug.tools.tips.1/

LPC1700 series overview– http://ics.nxp.com/support/training/lpc1700.overview/

Introduction to NXP's LPC4300 Cortex-M4 based digital controller– http://ics.nxp.com/support/training/lpc4300.intro/

Introduction to NXP's LPC4300 advanced peripherals– http://ics.nxp.com/support/training/lpc4300.peripherals/

LPCXpresso introduction– http://ics.nxp.com/support/training/lpcxpresso.intro/

Learn Eclipse the LPCXpresso way – http://ics.nxp.com/support/training/learn.eclipse.lpcxpresso/

Simplifying USB with NXP's lowest-cost ARM MCUs – http://ics.nxp.com/support/training/lpc1000.debug.tools.tips.1/

New Cortex-M training videos

Cortex-M4

LPCXpresso

Cortex-M3

Cortex-M0

USB

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Q&A

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