Chapter 6 code

2022-01-28 21:10:14 +00:00
parent fd4b0cb544
commit 881355daaa
23 changed files with 723 additions and 33 deletions
@@ -0,0 +1,93 @@
+"""Send this code, run and watch the repl.
+Then turn the wheel slowly to see the change"""
+import board
+import rp2pio
+import adafruit_pioasm
+import array
+
+program = """
+; use the osr for count
+; input pins c1 c2
+
+    set y, 0            ; clear y
+    mov osr, y          ; and clear osr
+read:
+    ; x will be the old value
+    ; y the new values
+    mov x, y            ; store old Y in x
+    in null, 32         ; Clear ISR - using y
+    in pins, 2          ; read two pins into y
+    mov y, isr
+    jmp x!=y, different ; Jump if its different
+    jmp read            ; otherwise loop back to read
+
+different:
+    ; x has old value, y has new.
+    ; extract the upper bit of X.
+    in x, 31             ; get bit 31 - old p1 (remember which direction it came in)
+    in null, 31         ; keep only 1 bit
+    mov x, isr          ; put this back in x
+    jmp !x, c1_old_zero
+
+c1_old_not_zero:
+    jmp pin, count_up
+    jmp count_down
+
+c1_old_zero:
+    jmp pin, count_down
+    ; fall through
+count_up:
+    ; for a clockwise move - we'll add 1 by inverting
+    mov x, ~ osr        ; store inverted OSR on x
+    jmp x--, fake       ; use jump to take off 1
+fake:
+    mov x, ~ x          ; invert back
+    jmp send
+count_down:
+    ; for a clockwise move, just take one off
+    mov x, osr          ; store osr in x
+    jmp x--, send       ; dec and send
+send:
+    ; send x.
+    mov isr, x          ; send it
+    push noblock        ; put ISR into input FIFO
+    mov osr, x          ; put X back in OSR
+    jmp read            ; loop back
+"""
+
+assembled = adafruit_pioasm.assemble(program)
+
+## set up a statemachine
+left_enc = rp2pio.StateMachine(
+    assembled,
+    frequency=0,
+    first_in_pin=board.GP20,
+    jmp_pin=board.GP21,
+    in_pin_count=2
+)
+
+right_enc = rp2pio.StateMachine(
+    assembled,
+    frequency=0,
+    first_in_pin=board.GP26,
+    jmp_pin=board.GP27,
+    in_pin_count=2
+) 
+
+buffer = array.array('i', [0])
+
+left_data = 0
+right_data = 0
+
+while True:
+    # read data from the fifo   
+    if left_enc.in_waiting:
+        left_enc.readinto(buffer)
+        left_data = buffer[0]
+        # print it.
+        print(left_data, right_data)
+    if right_enc.in_waiting:
+        right_enc.readinto(buffer)
+        right_data = buffer[0]
+        # print it.
+        print(left_data, right_data)