Hello all, thanks for the community, you guys are great, I was able to make progress from my last post.
I have a question in regard to my code for a project I started in school.
I was able to equate addresses, initialize the clock pins, and define the I/O pins for use.
I wrote a code that steps through the three colors on the on board LED. What I aim to do now, is to take input from a pin PORTA_PCR13 and set the led to one color when the button is not pressed, and another color when the button is pressed.
In C++ I would use an If, Then statement. However, I am unsure as to how I can implement this in ASM. Below is my code.
Any advice?
;Memory Address information found in the KL25P80M48SF0RM document |||||||||||||||| ;/////////////////////////////////////////////////////////////////////////////////
SIM_SCGC5 EQU 0x40048038 ;SIM_SCGC5 address The control for each ports Clock Gate PORTB_PCR18 EQU 0x4004A000 + 4 * 18 ;PORTB_PCR18 address LED Pin for RED
;Our added code to the example code found above in the lab manual PORTB_PCR19 EQU 0x4004A04C ;PORTB_PCR19 address LED Pin for GREEN PORTA_PCR13 EQU 0x40049034 ;PORTA_PCR13 address Pin used for button PORTD_PCR1 EQU 0x4004C004 ;PORTD_PCR1 address LED Pin for BLUE
GPIOA_PDDR EQU 0x400FF014 ;GPIOA_PDDR Register Address PDDR is Port Data Direction Register GPIOB_PDDR EQU 0x400FF054 ;GPIOA_PDDR Register Address This sets the pin as input or output GPIOD_PDDR EQU 0x400FF0D4 ;GPIOB_PDDR Register Address GPIOA_PDIR EQU 0x400FF010 ;GPIOA_PDIR Register Address This is the Port Data Input Register GPIOB_PDOR EQU 0x400FF040 GPIOD_PDOR EQU 0x400FF0C0 AREA asm_area, CODE, READONLY EXPORT asm_main
asm_main ;assembly entry point for C function, do not delete ; Add program code below here
;Initialize clock pins ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||| ;/////////////////////////////////////////////////////////////////////////////////
BL init_gpio
loop B loop init_gpio LDR R0,=SIM_SCGC5 ;Load address of SIM_SCGC5 to R0 LDR R1,[R0] ;Put value of SIM_SCGC5 into R1 LDR R2,=0x00003E00 ;Load value to turn on all port clocks into R2 ORRS R1,R2 ;OR R2 into R1 for use of masking STR R1,[R0] ;Put value back into SIM_SCGC5, ;This puts 0011111000000000, bianary of 3E, into the Sim_SCGC5 register ;Which turns on the port clocks A-E. See Onur Yilmaz - GPIO.ppt Slide 3 LDR R0,=PORTB_PCR18 ;Load address of PORTB_PCR18 to R0 LDR R1,=0x00000100 ;Load value to R1 STR R1,[R0] ;Put value into PORTB_PCR18 LDR R0,=PORTB_PCR19 ;Load address of PORTB_PCR19 to R0 LDR R1,=0x00000100 ;Load value to R1 STR R1,[R0] ;Put value into PORTB_PCR19
LDR R0,=PORTD_PCR1 ;Load address of PORTD_PCR1 to R0 LDR R1,=0x00000100 ;Load value to R1 STR R1,[R0] ;Put value into PORTD_PCR1
LDR R0,=PORTA_PCR13 ;Load address of PORTA_PCR13 to R0 LDR R1,=0x00000102 ;Load value to R1 STR R1,[R0] ;Put value into PORTA_PCR13 ;\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\ ;Initialize GPIO's and setup I/O status |||||||||||||||||||||||||||||||||||||||||| ;/////////////////////////////////////////////////////////////////////////////////
LDR R0,=GPIOA_PDDR ;Load address of GPIOA to R0 LDR R1,=0x00000000 ;Load value to R1 Set to ALL INPUTS. O input, 1 Output. Convert to Binary to see what PTB is set STR R1,[R0] ;Put value into GPIOA LDR R0,=GPIOB_PDDR ;Load address of GPIOB to R0 LDR R1,=0x000C0000 ;Load value to R1 Outputs configured on PTB18 and PTB19, the LEDs on thos ports as outputs STR R1,[R0] ;Put value into GPIOB LDR R0,=GPIOD_PDDR ;Load address of GPIOD to R0 LDR R1,=0x00000002 ;Load value to R1 Output configured on PTC1 STR R1,[R0] ;Put value into GPIOD ;this is where a loop would exist ;read the PDIR to take an input and branch to a location that will enable the color ;loop ;LDR R0,=GPIOA_PDIR ;LDR R1,[R0] ;LDR R2, =0x00002000 ;Must check this block of code ;ANDS R1,R2 ;Not sure if it takes an input from pin A13 ;CMP R1,R2 ;BEQ loop LDR R0,=GPIOB_PDOR LDR R1,=0xFFFFFFFF STR R1,[R0] LDR R0,=GPIOD_PDOR LDR R1,=0xFFFFFFFF STR R1,[R0] LDR R0,=GPIOB_PDOR LDR R1,=0x00040000 STR R1,[R0] LDR R0,=GPIOB_PDOR LDR R1,=0xFFFFFFFF STR R1,[R0] LDR R0,=GPIOB_PDOR LDR R1,=0x00080000 STR R1,[R0]
LDR R0,=GPIOB_PDOR LDR R1,=0xFFFFFFFF STR R1,[R0] LDR R0,=GPIOD_PDOR LDR R1,=0xFFFFFFFD STR R1,[R0] LDR R0,=GPIOD_PDOR LDR R1,=0xFFFFFFFF STR R1,[R0] BX LR
;Control indivual pins or LED's |||||||||||||||||||||||||||||||||||||||||||||||||| ;///////////////////////////////////////////////////////////////////////////////// LDR R2, =0x00000000 ;Counter to see Iif button is held down LDR R4,= 0x00000000 ;Counter for LED COLOR CYLE
;/////////////////////////////////////////////////// ; Put constants here
AREA data_area, DATA, READWRITE ; Put variables here END
Thanks in advance.
Solved! Go to Solution.
James
You will need to check the register contents and also the CCR flags that are affected when stepping.
- the CMP is not required because the AND already sets the CCR with the result of whether it was zero or not
- you certainly need a jump after the first block otherwise it just continues into the second and you always have the same result at the end
Regards
Mark
James
Read the value to a register, mask the bit of interest and then do a compare.
CMP R0, #0
BEQ.N _label1
do things when true and return or jump to _label2
_label1
do things when false
_label2
continue
However you really should start using C asap because I don't think anyone is really interested with messing about in assembler (maybe back in the 1970s it would have been used). In any case just write what you want in C and see what the compiler spits out in assembled code since it is the easiest way to learn.
Regards
Mark
After reviewing your first comment and code I wrote the following (this was placed after my block of comments and before clearing GPIOB_PDOR):
LDR R0,=GPIOA_PDIR | ||||||
LDR R1,[R0] | ||||||
LDR R2, =0x00002000 ;Mask the bit of interest, this is for PTA13 | ||||||
ANDS R1,R2 | ||||||
CMP R1,R2 ;Compare the results | ||||||
BEQ _onColor |
_offColor
LDR R0,=GPIOB_PDOR | |
LDR R1,=0x00080000 | |
STR R1,[R0] |
_onColor
LDR R0,=GPIOD_PDOR | |
LDR R1,=0xFFFFFFFD | |
STR R1,[R0] |
I shorted pin PTA13 to ground and when I step through the code, I expected to see the pin color I specified light up, yet it does not. This code chronologically steps throgh each line, dispite creating the labels _onColor and _offColor
.
I am not sure what I am doing wrong.
I did not know I could write in C then transcribe to ASM. I will try that for the next assignment, this ASM is 90% done. All I need is to get the button functionality for this project.
The class is 50% ASM and 50% C
Hello james,
I wrote a part of the code according to Mr. Mark's instructions.
It was a little modified to pass the GCC assembler.
LOOP: LDR R0,=GPIOA_PDIR LDR R1,[R0] LDR R2, =0x00002000 AND R1,R2 BNE _onColor
_offColor:
LDR R0,=GPIOB_PDOR LDR R1,=0x00080000 STR R1,[R0] B NEXT
_onColor: LDR R0,=GPIOD_PDO LDR R1,=0xFFFFFFFD STR R1,[R0]
NEXT: /* do something? */
B LOOP
Can it help you?
Best regards,
Yasuhiko Koumoto.
Thank you for everyone's help.
I was able to take information learned from Mark as well as a buddies sample code, and write this code which works like expected.
loop
LDR R0,=GPIOA_PDIR
LDR R1,[R0]
LDR R2, =0x00002000 ;Mask the bit of interest
ANDS R1,R2
LDR R6, =0x00000000;
CMP R1, R6 ;Test to see if button is pressed
BNE _offColor
_onColor
LDR R0,=GPIOD_PDOR
LDR R1,=0xFFFFFFFF ;Clears the registers
STR R1,[R0]
LDR R0,=GPIOB_PDOR
LDR R1,=0xFFFFFFFF ;Also clears the registers
STR R1,[R0]
LDR R1,=0x00080000
STR R1,[R0]
LDR R0,=GPIOD_PDOR
LDR R1,=0xFFFFFFFD
STR R1,[R0]
B loop
_offColor
LDR R0,=GPIOB_PDOR
LDR R1,=0xFFFFFFFF ;This clears the register
STR R1,[R0]
LDR R0,=GPIOD_PDOR
LDR R1,=0xFFFFFFFF ;This also clears the registers for the other color pin
STR R1,[R0]
LDR R0,=GPIOB_PDOR
LDR R1,=0x00080000 ;This sets the color of the pin of choice.
STR R1,[R0]
B loop
yasuhikokoumoto, your code looks much more simpler then mine. I am going to try to rewrite it using your code and see if I can get it to work as well.
Thank you mjbcswitzerland
James
You will need to check the register contents and also the CCR flags that are affected when stepping.
- the CMP is not required because the AND already sets the CCR with the result of whether it was zero or not
- you certainly need a jump after the first block otherwise it just continues into the second and you always have the same result at the end
Regards
Mark