EV-LM3S811 blinking LED in assembler

Intellectual 450 points

dalewheat

Replies: 4

Views: 3934

For the really hard core folk that want to get to the bare metal of the new Stellaris parts, here is a minimal program that will blink the user LED on the EV-LM3S811 board, in glorious ARM assembler code, which will compile under the uVision demo that is supplied with the evaluation kit:

; blink.s - blink user LED on Luminary Micro EV-LM3S811 (Cortex-M3)

AREA TEXT, CODE, READONLY
CODE16

; vector table

DCD 0x20002000
DCD Reset_Handler
DCD iloop
DCD iloop

; start the program here

Reset_Handler
EXPORT Reset_Handler

; initialize GPIO port C, pin 5 as output

RCGC2 EQU 0x400FE108 ; run-mode clock gating control 2
RCGC2_PORTC EQU 1 <

ldr r0, =RCGC2

ldr r1, =RCGC2_PORTC
str r1, [r0]

GPIODIR_PORTC EQU 0x40006400
GPIO_PC5 EQU 1 <

ldr r0, =GPIODIR_PORTC

ldr r1, =GPIO_PC5
str r1, [r0]

GPIODATA_PORTC EQU 0x40006000

ldr r0, =GPIODATA_PORTC + (GPIO_PC5 <

loop

ldr r1, =GPIO_PC5
str r1, [r0]

ldr r2, =1000000
1 subs r2, r2, #1
bne %1

ldr r1, =0
str r1, [r0]

ldr r2, =1000000
1 subs r2, r2, #1
bne %1

b loop ; and do it again

; an infinite loop in place of real exception handlers

iloop b iloop

; the end

END

[end-of-file]

Note that you will need to indent all the lines that don't start with a label, as this forum is protecting you from my code in its original beauty.

Questions? Comments? Let me know!

Dale

Intellectual 450 points

dalewheat

• Oct 27, 2006 3:02 AM
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4 Replies

• Intellectual 470 points

  

  englere

  

  • Oct 30, 2006 4:07 PM

  Thanks for the example! I want to experiment with asm a little more.
  
  I think you can use the "Code" button on the web page here to tell it not to mess up your indenting. When entering code in a message, try highlighting the code and then press the code button.
  
  Here's a test - I want to see if this works:
  
  

  Code:

  ; comment - not indented label:     ; not indented   code1    ; indented 2 spaces     code2  ; indented 4 spaces lable2:    ; not indented

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• Intellectual 450 points

  

  dalewheat

  

  • Oct 30, 2006 4:17 PM

  Oh, that's much better! Let me try this again, using the appropriate tools this time:
  
  

  Code:

  ; blink.s - blink user LED on Luminary Micro EV-LM3S811 (Cortex-M3)     AREA    TEXT, CODE, READONLY     CODE16     ; vector table     DCD    0x20002000     DCD    Reset_Handler     DCD    iloop     DCD    iloop     ; start the program here Reset_Handler     EXPORT Reset_Handler     ; initialize GPIO port C, pin 5 as output RCGC2            EQU 0x400FE108        ; run-mode clock gating control 2 RCGC2_PORTC        EQU 1 <2            ; PORTC clock enable     ldr    r0, =RCGC2     ldr    r1, =RCGC2_PORTC     str    r1, [r0] GPIODIR_PORTC    EQU 0x40006400 GPIO_PC5        EQU 1 <5     ldr    r0, =GPIODIR_PORTC          ldr    r1, =GPIO_PC5     str    r1, [r0] GPIODATA_PORTC    EQU 0x40006000     ldr    r0, =GPIODATA_PORTC + (GPIO_PC5 <2) loop          ldr    r1, =GPIO_PC5     str    r1, [r0]     ldr    r2, =1000000 1    subs    r2, r2, #1     bne    %1     ldr    r1, =0     str    r1, [r0]          ldr    r2, =1000000 1    subs    r2, r2, #1     bne    %1     b    loop    ; and do it again     ; an infinite loop in place of real exception handlers iloop    b    iloop     ; the end     END [end-of-file]

  
  
  Awesome! You might actually be able to cut+paste and get it to work! Thanks for the tip.
  
  Dale

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• Prodigy 10 points

  

  petej

  

  • Dec 22, 2006 8:17 PM

  Dale,
  
  Thanks for posting the code. Do you have any extra ASM to switch clocks to run the CPU at 50 MHz?
  
  Out of interest, I created a very simple 'blinky' program in C using RV3 running the CPU at 50 MHz (SYSDIV _4) - the fastest I could get it to go using the LM Library calls was 541 KHz! Hence my request for ASM code to set the PLL.
  
  Pete

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• Genius 4070 points

  

  awneil

  

  • May 16, 2008 9:55 PM

  This looks interesting - but how does one set up an Assembler project in code_suite?
  
  The documentation seems to be entirely focussed on C/C++...

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