Chapter 6 code

ch-6/2-techniques/debugging_isr.py

@@ -0,0 +1,44 @@
+"""Sometimes, you need to debug a register. 
+ISR is a bit special - when you push, you destroy it's content -
+    you'll need to restore this. If you remove the mov from x, 
+    it is set to 0s.
+It'll cost a few instructions to do."""
+import rp2pio
+import adafruit_pioasm
+import array
+
+
+program = """
+.program debug_register    
+    set y, 21       ; use y to set ISR
+    mov isr, y
+
+; debug isr
+        mov x, isr  ; preserve isr - pushing destroys it
+        push noblock
+        mov isr, x  ; restore isr
+; done debug
+
+; debug isr
+        mov x, isr  ; preserve isr - pushing destroys it
+        push noblock
+        mov isr, x  ; restore isr
+; done debug
+"""
+
+assembled = adafruit_pioasm.assemble(program)
+
+## set up a statemachine
+sm = rp2pio.StateMachine(
+    assembled,
+    frequency=2000,
+)
+
+buffer = array.array('I', [0])
+
+# read the data
+sm.readinto(buffer)
+print("first push: {0} 0b{0:08b} 0x{0:x}".format(buffer[0]))
+
+sm.readinto(buffer)
+print("second:     {0} 0b{0:08b} 0x{0:x}".format(buffer[0]))