[Feature] allow SPI creation with high speed SPIM3

[ladyada]

perhaps in the variant you can specify you want SPI/SPI1/etc to use the high speed SPIM3 periph. then we can have 32mhz instead of 8mhz for TFT for easy 4x speedup :)

[dhalbert]

Note that I was unable to get SPIM3 to work with the SoftDevice enabled: adafruit/circuitpython#1222

[ladyada]

kk - here's some more demos i found..i dont see any repro of our issue...maybe worth knocking out a quick proof-of-concept in arduino (e.g. swapping the spi* for spim* to see if it will work)

https://jimmywongbluetooth.wordpress.com/2019/10/05/lcd-display-on-nrf52840/
https://jimmywongbluetooth.wordpress.com/2019/04/30/overview-on-spi-master-slave-on-nrf52-series/
https://devzone.nordicsemi.com/f/nordic-q-a/42682/nrf52840-spim3-hardware-chip-select-functionality-sdk-support

[hathach]

[jimmywong2003]

Here are the example code

`
void drv_ili9341_put_gfx(uint16_t x, uint16_t y, uint16_t w, uint16_t h, uint8_t const *p_lcd_data)
{
drv_ili9341_set_window(x, y, w, h);

    uint8_t tx_buff[1];
    nrfx_err_t err_code;

    nrfx_spim_xfer_desc_t xfer_desc = NRFX_SPIM_XFER_TX(tx_buff, 1);
    uint32_t flags = NRFX_SPIM_FLAG_NO_XFER_EVT_HANDLER;

    // send LCD command
    tx_buff[0] = ILI9341_RAMWR;
    err_code = nrfx_spim_xfer_dcx(&spi_ili9341_instance, &xfer_desc, flags, 1);
    APP_ERROR_CHECK(err_code);

    //nrf_delay_ms(1);
    uint32_t len = (uint32_t)w * (uint32_t)h * 2;
    uint32_t pos = 0, stp = 0;

    // send LCD data
    for (pos = 0; pos < len; pos += stp)
    {
            stp = MIN((len - pos), 65534);
            //NRF_LOG_INFO("gfx %d", stp);
            xfer_desc.tx_length = stp;
            xfer_desc.p_tx_buffer = p_lcd_data + pos;
            err_code = nrfx_spim_xfer_dcx(&spi_ili9341_instance, &xfer_desc, flags, 0);
            APP_ERROR_CHECK(err_code);
    }`

[hathach]

Here are the example code

`
void drv_ili9341_put_gfx(uint16_t x, uint16_t y, uint16_t w, uint16_t h, uint8_t const *p_lcd_data)
{
drv_ili9341_set_window(x, y, w, h);

    uint8_t tx_buff[1];
    nrfx_err_t err_code;

    nrfx_spim_xfer_desc_t xfer_desc = NRFX_SPIM_XFER_TX(tx_buff, 1);
    uint32_t flags = NRFX_SPIM_FLAG_NO_XFER_EVT_HANDLER;

    // send LCD command
    tx_buff[0] = ILI9341_RAMWR;
    err_code = nrfx_spim_xfer_dcx(&spi_ili9341_instance, &xfer_desc, flags, 1);
    APP_ERROR_CHECK(err_code);

    //nrf_delay_ms(1);
    uint32_t len = (uint32_t)w * (uint32_t)h * 2;
    uint32_t pos = 0, stp = 0;

    // send LCD data
    for (pos = 0; pos < len; pos += stp)
    {
            stp = MIN((len - pos), 65534);
            //NRF_LOG_INFO("gfx %d", stp);
            xfer_desc.tx_length = stp;
            xfer_desc.p_tx_buffer = p_lcd_data + pos;
            err_code = nrfx_spim_xfer_dcx(&spi_ili9341_instance, &xfer_desc, flags, 0);
            APP_ERROR_CHECK(err_code);
    }`

Thank for the helps, It is almost done on this branch :) https://github.com/adafruit/Adafruit_nRF52_Arduino/tree/spi-dma