Revision 0:31dce9a8752d, committed 2020-11-27

Comitter:

bky

Date:

Fri Nov 27 21:14:54 2020 +0000

Commit message:

test 1

Changed in this revision

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Fri Nov 27 21:14:54 2020 +0000
@@ -0,0 +1,14 @@
+
+#include "mbed.h"
+extern "C" int my_leds(int value);
+// Initialize LEDs
+DigitalOut myled1(LED1);
+DigitalOut myled2(LED2);
+DigitalOut myled3(LED3);
+DigitalOut myled4(LED4);
+int main () {
+  for (int i = 0; i <=15; i++){
+      my_leds(i);
+  }
+  while (1){};
+}
\ No newline at end of file

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mbed.bld	Fri Nov 27 21:14:54 2020 +0000
@@ -0,0 +1,1 @@
+https://os.mbed.com/users/mbed_official/code/mbed/builds/65be27845400
\ No newline at end of file

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/my_asm.s	Fri Nov 27 21:14:54 2020 +0000
@@ -0,0 +1,46 @@
+    AREA my_asm, CODE, READONLY
+; Export my_leds function symbol for linker
+    EXPORT my_leds
+my_leds
+;
+; ARM Assembly language function to set LEDs to a value passed from C   
+; LEDs get low order nybble (passed from C compiler in R0)
+; Destination bits are 23, 21, 20, 18 for bits 3, 2, 1, 0 respectively
+;
+; Load GPIO Port 1 base address in register R1 
+    PUSH    {R1, R2, LR}
+    LDR     R1, =0x2009C03C    ; 0x2009C03C = FIOCLR address
+    LDR     R2, =0xB40000      ; Pattern for all lights
+    STR     R2, [R1]           ; Clear all lights
+    LDR     R1, =0x2009C038    ; 0x2009C038 = FIOSET address
+
+    BFI     R2, R0, #20, #4    ; Insert bit 3 in the correct position
+    BFI     R2, R0, #19, #3    ; Insert bits 1 and 2 in the correct position
+    BFI     R2, R0, #18, #1    ; Insert bit 1 in the correct position
+
+    AND     R2, R2, #0xB40000  ; Apply bit mask
+    
+    STR     R2, [R1]           ; Store R2 at FIOSET address to light LEDs
+    
+    BL      my_wait            ; Branch to my_wait subroutine
+    POP     {R1, R2, LR}
+    BX      LR                 ; Return from function
+    ALIGN                      ; Pad for word alignment
+    
+my_wait
+    PUSH    {R4, R5}        ;get 2 regs to use R4 is i, R5 is limit
+    MOV.W   R4, #0          ;int i = 0
+    LDR     R5, =20000000   ;Set limit
+loop_entry
+    CMP     R4, R5          ;R4 - R5 (i - limit)
+    BGE     loop_exit       ;if i >= limit exit
+                            ;loop body is empty
+    ADD     R4, R4, #1      ;i++
+    B       loop_entry      ;Return
+loop_exit
+    POP     {R4, R5}        ;restore regs    
+    BX      LR              ;Return
+    ALIGN
+    END
+    
+    END                        ; End of assembly
\ No newline at end of file