SPI Init with default phase and polarization

[juan0fran]

On spi.c [https://github.com/raspberrypi/pico-sdk/blob/2062372d203b372849d573f252cf7c6dc2800c0a/src/rp2_common/hardware_spi/spi.c#L21C6-L21C14]

there is not the option to change polarity/phase unless the library code is modified.

A spi-specific function should be added (to have retro-compatibility for those libs already using this library) to something like:

uint spi_init_pol_phase(spi_inst_t *spi, uint baudrate, spi_cpol_t pol, spi_cpha_t phase) {
    spi_reset(spi);
    spi_unreset(spi);

    uint baud = spi_set_baudrate(spi, baudrate);
    spi_set_format(spi, 8, pol, phase, SPI_MSB_FIRST);
    // Always enable DREQ signals -- harmless if DMA is not listening
    hw_set_bits(&spi_get_hw(spi)->dmacr, SPI_SSPDMACR_TXDMAE_BITS | SPI_SSPDMACR_RXDMAE_BITS);

    // Finally enable the SPI
    hw_set_bits(&spi_get_hw(spi)->cr1, SPI_SSPCR1_SSE_BITS);
    return baud;
}

[lurch]

there is not the option to change polarity/phase unless the library code is modified.

Can't you simply call spi_set_format after calling the existing spi_init ?

[juan0fran]

Actually yes, but that would require to define spi_set_format as non-static. Either way would work.

[peterharperuk]

spi_set_format is inline, you should be able to call it