PIO: '@rp2.asm_pio(out_init=' failing to set pin state properly

[mungewell]

I've got another 'weirdness' going on....

I have a PIO StateMachine:

# 'SM_ENCODE' State Machine for differential output
@rp2.asm_pio(out_init=(rp2.PIO.OUT_HIGH, rp2.PIO.OUT_LOW))

def encode_dmc2():
    irq(block, 4)                   # Wait for Sync'ed start

    wrap_target()
    label("toggle-0")
    mov(pins, invert(pins)) [14]    # Always toogle pin at start of cycle, "0" or "1"

    jmp(pin, "toggle-1")            # Check output of SM-1 buffer, jump if 1

    jmp("toggle-0") [15]

    label("toggle-1")
    mov(pins, invert(pins)) [15]    # Toggle pin to signal '1'
    wrap()

Which generates a differential signal, two outputs which should operate anti-phase to each other.

BUT, sometimes after reloading the StateMachine the outputs are IN-PHASE... anyone seen this happen? Any suggestions on how to ensure that the two outputs are correctly set?

(ps. I don't have any more space for PIO instructions, the PIO are completely full).

[mungewell]

OK, this was caused by my messing with Muxing, and having both GPIO set zero...

        # force pins 9 & 10 to mux to PIO
        mem32[0x40014000 + 0x04c] = (mem32[0x40014000 + 0x04c] & 0xFFFFFFE0) + 0x6
        mem32[0x40014000 + 0x054] = (mem32[0x40014000 + 0x054] & 0xFFFFFFE0) + 0x6
        if high_output_level:
            # pin 10 : force muxing to use GPIO block (ie force low)
            mem32[0x40014000 + 0x054] = (mem32[0x40014000 + 0x054] & 0xFFFFFFE0) + 0x5

            print("HIGH level selected")
        else:
            print("MIC level selected")

Now they are set high/low and I don't see the problem.