src/uart_tx.pio


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.program uart_tx
.side_set 1 opt

.wrap_target
    pull    block           side 1      [7]     ; IDLE / STOP bit
    set     x, 7            side 0      [7]     ; START bit
bitloop:
    out     pins, 1                             ; 8 DATA bits
    jmp     x--, bitloop                [6]
.wrap