examples: Add example script to flash an LED using inline assembler.

dpgeorge · dpgeorge · commit 71dcd5198944 · 2014-04-12T18:27:23.000+01:00
diff --git a/examples/asmled.py b/examples/asmled.py
@@ -0,0 +1,81 @@
+# flash LED #1 using inline assembler
+@micropython.asm_thumb
+def flash_led(r0):
+    movw(r1, (stm.GPIOA + stm.GPIO_BSRRL) & 0xffff)
+    movt(r1, ((stm.GPIOA + stm.GPIO_BSRRL) >> 16) & 0x7fff)
+    movw(r2, 1 << 13)
+    movt(r2, 0)
+    movw(r3, 0)
+    movt(r3, 1 << 13)
+
+    b(loop_entry)
+
+    label(loop1)
+
+    # turn LED on
+    str(r2, r1, 0)
+
+    # delay for a bit
+    movw(r4, 5599900 & 0xffff)
+    movt(r4, (5599900 >> 16) & 0xffff)
+    label(delay_on)
+    subs(r4, r4, 1)
+    cmp(r4, 0)
+    bgt(delay_on)
+
+    # turn LED off
+    str(r3, r1, 0)
+
+    # delay for a bit
+    movw(r4, 5599900 & 0xffff)
+    movt(r4, (5599900 >> 16) & 0xffff)
+    label(delay_off)
+    subs(r4, r4, 1)
+    cmp(r4, 0)
+    bgt(delay_off)
+
+    # loop r0 times
+    subs(r0, r0, 1)
+    label(loop_entry)
+    cmp(r0, 0)
+    bgt(loop1)
+
+# flash LED #1 using inline assembler
+# this version uses the convenience assembler operation 'movwt'
+@micropython.asm_thumb
+def flash_led_v2(r0):
+    movwt(r1, stm.GPIOA + stm.GPIO_BSRRL)
+    movwt(r2, 1 << 13)
+    movwt(r3, 1 << (16 + 13))
+
+    b(loop_entry)
+
+    label(loop1)
+
+    # turn LED on
+    str(r2, r1, 0)
+
+    # delay for a bit
+    movwt(r4, 5599900)
+    label(delay_on)
+    subs(r4, r4, 1)
+    cmp(r4, 0)
+    bgt(delay_on)
+
+    # turn LED off
+    str(r3, r1, 0)
+
+    # delay for a bit
+    movwt(r4, 5599900)
+    label(delay_off)
+    subs(r4, r4, 1)
+    cmp(r4, 0)
+    bgt(delay_off)
+
+    # loop r0 times
+    subs(r0, r0, 1)
+    label(loop_entry)
+    cmp(r0, 0)
+    bgt(loop1)
+
+flash_led_v2(5)
