Revision 0:c40fd5b610ee, committed 2019-03-09

Comitter:

hudakz

Date:

Sat Mar 09 10:56:02 2019 +0000

Commit message:

Initial release.

Changed in this revision

diff -r 000000000000 -r c40fd5b610ee main.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Sat Mar 09 10:56:02 2019 +0000
@@ -0,0 +1,28 @@
+#include "mbed.h"
+// This program will blink LED1 and LED4
+// using assembly language for LED1 and
+// API functions for LED4
+// declare external assembly language function (in a *.s file)
+extern "C" int my_asm(int value);
+// declare LED outputs – let C set them up as output bits
+DigitalOut myled1(LED1);
+DigitalOut myled4(LED4);
+ 
+int main() {
+
+    int value = 0;
+
+
+    // loop forever
+    while(1) {
+      //call assembly language function to control LED1
+      my_asm(value);
+      //API function to control LED4
+      myled4 = value;
+      // flip value and wait
+      value = ~ value;
+      wait(0.2);
+    }
+}
+ 
+ 

diff -r 000000000000 -r c40fd5b610ee mbed.bld
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mbed.bld	Sat Mar 09 10:56:02 2019 +0000
@@ -0,0 +1,1 @@
+https://os.mbed.com/users/mbed_official/code/mbed/builds/65be27845400
\ No newline at end of file

diff -r 000000000000 -r c40fd5b610ee my_asm.s
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/my_asm.s	Sat Mar 09 10:56:02 2019 +0000
@@ -0,0 +1,31 @@
+    AREA asm_func, CODE, READONLY
+
+; Export my_asm function location so that C compiler can find it and link
+
+
+    EXPORT my_asm
+my_asm
+;
+; ARM Assembly language function to set LED1 bit to a value passed from C   
+; LED1 gets value (passed from C compiler in R0)
+; LED1 is on GPIO port 1 bit 18
+; See Chapter 9 in the LPC1768 User Manual
+; for all of the GPIO register info and addresses
+; Pinnames.h has the mbed modules pin port and bit connections
+;
+; Load GPIO Port 1 base address in register R1 
+    LDR     R1, =0x2009C020 ; 0x2009C020 = GPIO port 1 base address
+; Move bit mask in register R2 for bit 18 only
+    MOV.W   R2, #0x040000   ; 0x040000 = 1<<18 all "0"s with a "1" in bit 18
+; value passed from C compiler code is in R0 - compare to a "0" 
+    CMP     R0, #0          ; value == 0 ?
+; (If-Then-Else) on next two instructions using equal cond from the zero flag
+    ITE EQ
+; STORE if EQ - clear led 1 port bit using GPIO FIOCLR register and mask
+    STREQ   R2, [R1,#0x1C]  ; if==0, clear LED1 bit
+; STORE if NE - set led 1 port bit using GPIO FIOSET register and mask
+    STRNE   R2, [R1,#0x18]  ; if==1, set LED1 bit
+; Return to C using link register (Branch indirect using LR - a return)
+    BX      LR
+    END
+ 
\ No newline at end of file