Single Chip Microcontrollers

7765JMount Druitt College of TAFELesson 2

Plagiarism Plagiarism is the practice of claiming or

implying original authorship of (or incorporating material from) someone else's written or creative work, in whole or in part, into one's own without adequate acknowledgement

Within academia, plagiarism by students, professors, or researchers is considered academic dishonesty or academic fraud and offenders are subject to academic censure

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Plagiarism [2]

Common forms of plagiarism Downloading, borrowing or stealing an assignment

and presenting it as your own work. Copying a section of a book or article and submitting

it as your own work. Copying, cutting and pasting text from an electronic

source and submitting it as your own work. Using the words or ideas of someone else and

presenting them as your own. Relying too much on other people's material. Use

your own words as much as you can.

© Mike Stacey 2008

Plagiarism [3]

Plagiarism & the Internet “The internet can be a great source of information

and an effective research tool. However, just because electronic information is easily available does not mean it is 'free'. Remember that the information you find online should be referenced, just like any other source. Online sources should be used with care, fully acknowledged and evaluated in the same way you would any print-based source of information.”[1]References[1] "plagiarize." Merriam-Webster Online Dictionary. 2008.

Merriam-Webster Online. 8 May 2008, <http://www.merriam-ebster.com/dictionary/plagiarize>

© Mike Stacey 2008

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Flow Charts – example from prac 2

initialise stack pointer

set temp reg

write temp to DDRA

load r17 = 00h

load r18 = 01h

RESET

load r19 = 02h

INIT_DATA

r17 < r18?SORT

smallest = r18

r19 < smallest? smallest = r19

T

F

T

F

smallest = r17

output smallest to Port A

DISPLAY

START

END

INITdef smallest = r20

def temp = r16

You need to show this level of detail in your assignment reports.

© Mike Stacey 2008

I/O Ports [1] 8 bit bi-directional Individual pins can be configured as either

input or output 3 address locations for the port

One for Data Register PORTA One for Data Direction Register DDRA One for Port A input pins PINA

Check out the memory map on page 11 and see what range of address space is used for the ports.

© Mike Stacey 2008

I/O Ports [2] Port A has an alternate function as analog inputs for the

ADC. If some of the pins are configured as outputs care must be taken to ensure that none of the outputs switches state as this may corrupt the result of the conversion.

The DDRAn bit in the DDRA register selects direction of that pin (read or write, output or input) If DDAn = 1 then DDAn is an input pin (READ)

Example:ser temp

out DDRC, temp

If DDAn = 0 then DDAn is an output pin (WRITE)

Example:clr temp

out DDRA, temp

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Memory Maps. See pp 7-11 of data sheets

Conventional memory addressing modes can be used on the registers as well. This is enabled by the fact that the registers are assigned an address space of $00 - $1F

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Memory Map for 90S8535

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Register addressingThe registers are physically implemented in internal memory. The registers are accessed by using the address. This is invisible to the programmer.

Observe the register address space in AVR Studio

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Memory mapped I/O – see pp 17-18 of data sheets

Data going out to a port first goes to a space in RAM memory defined by an address and is then transferred out to the port’s output register.

The output register itself is also mapped to an address in memory space but, like the general purpose registers, this is not physically implemented in RAM

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Memory mapped I/O

Observe these addresses in AVR Studio

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Observe memory mapping in AVR Studio

Step through the ledbutton.asm program from prac exercise 1b.

Find r16 and r15 in the register section of the “memory view” What addresses do they have?

Find DDRA, DDRC, PINA, PORTC in memory What addresses do they have?