This should be fixable in your code. You're enabling the SM before the DMA channel is claimed and used - move pio_sm_set_enabled() out of simple_program_init() and after the call to pio_sm_config_xfer(). You may also need to add a 10-20us delay in software as the DMAC needs to do a descriptor fetch once it's enabled.
Statistics: Posted by jdb — Mon Jan 19, 2026 4:55 pm