MISO Line Misbehaving, no data received

[Alex Ross]

Hello,

I'm trying to get the SPI drivers working in slave mode. I have tested my master (Atmel L21) on an Arduino and I can see my message clearly. I'm trying to get nRF52833 working in slave mode but p_event->rx_amount always reports back 0.

I have tried all SPI modes (but I believe I'm operating in SPI Mode 2)

I only get a single blip on the MISO line that goes blips again on the next chip select toggle.

The module in question is a Laird part. It uses mappings like SPI = SIO_41, SIO_41 translates to pin 9 according to their documentation but maybe an expert can point out if this is wrong.

I am in a huge time crunch! This is based off of the spis example code but if any other example works for slave mode (and is better documented about how to get it into slave mode) I'd be open to switching to it.

Thanks!

int main(void)
{
    initialize();
    spi_if_init();
    start();

    for (;;)
    {
        spi_if_task();
        //(void)sd_app_evt_wait();
    }
}

#include <nrfx_spis.h>
#include "spi_interface.h"
#include "log.h"

#define SPIS_INSTANCE 2 /**< SPIS instance index. */


static volatile bool spis_xfer_done; /**< Flag used to indicate that SPIS instance completed the transfer. */

static uint8_t       m_tx_buf[8] = {9,10,11,12,13,14,15,16};
static uint8_t       m_rx_buf[16];
static const uint8_t m_length = sizeof(m_tx_buf);        /**< Transfer length. */

const nrfx_spis_t instance = NRFX_SPIS_INSTANCE(SPIS_INSTANCE);

void spi_if_event_handler(nrfx_spis_evt_t const * p_event,void * p_context);

void spi_if_init(void)
{
    nrfx_spis_config_t spis_config;
    spis_config.csn_pin               = NRF_GPIO_PIN_MAP(0,12);
    spis_config.miso_pin              = NRF_GPIO_PIN_MAP(0,4);
    spis_config.mosi_pin              = NRF_GPIO_PIN_MAP(0,8);
    spis_config.sck_pin               = NRF_GPIO_PIN_MAP(0,9);
//    spis_config.csn_pin               = NRF_GPIO_PIN_MAP(0,12);
//    spis_config.miso_pin              = NRF_GPIO_PIN_MAP(0,34);
//    spis_config.mosi_pin              = NRF_GPIO_PIN_MAP(0,32);
//    spis_config.sck_pin               = NRF_GPIO_PIN_MAP(0,30);
////    spis_config.csn_pin               = 12;
//    spis_config.miso_pin              = 34;
//    spis_config.mosi_pin              = 32;
//    spis_config.sck_pin               = 30;

    spis_config.mode         = NRF_SPIS_MODE_2;
	spis_config.bit_order    = NRF_SPIS_BIT_ORDER_MSB_FIRST;
	spis_config.csn_pullup   = 0;
	spis_config.miso_drive   = NRF_GPIO_PIN_H0H1;
	spis_config.def          = NRFX_SPIS_DEFAULT_DEF;
	spis_config.orc          = NRFX_SPIS_DEFAULT_ORC;
	spis_config.irq_priority = 1;

    nrfx_spis_init(&instance , &spis_config, spi_if_event_handler, SPIS_INSTANCE);
	nrfx_spis_buffers_set(&instance, m_tx_buf, m_length, m_rx_buf, m_length);

    nrf_gpio_cfg_output(4);
    nrf_gpio_cfg_input(32,NRF_GPIO_PIN_PULLDOWN);
    nrf_gpio_cfg_input(30,NRF_GPIO_PIN_PULLDOWN);
    nrf_gpio_cfg_input(12,NRF_GPIO_PIN_PULLDOWN);
}

void spi_if_event_handler(nrfx_spis_evt_t const * p_event,void * p_context)
{
    if (p_event->evt_type == NRFX_SPIS_XFER_DONE)
    {
        spis_xfer_done = true;
        __LOG(LOG_SRC_APP, LOG_LEVEL_INFO,"Transfer completed. Length: %d \n",p_event->rx_amount);

        __LOG(LOG_SRC_APP, LOG_LEVEL_INFO,"Transfer completed. Received: %d %d %d %d \n",(uint32_t)m_rx_buf[0],(uint32_t)m_rx_buf[1],(uint32_t)m_rx_buf[2],(uint32_t)m_rx_buf[3]);
    }
}
void spi_if_task(void)
{
    memset(m_rx_buf, 0, m_length);
    spis_xfer_done = false;

	nrfx_spis_buffers_set(&instance, m_tx_buf, m_length, m_rx_buf, m_length);

    while (spis_xfer_done == false)
    {
        __WFE();
    }
}

Laird module: 453-00041R

[haakonsh]

Can you replicate the problem on the nRF52DK? 

Can you enter a debug state, halt the cpu after you've initialized the SPIS, then read out the SPIS registers? 

[Alex Ross]

Thanks for the reply. Here's the readout of the registers. The inst index looks wrong to me. Is my pin assignment correct? Also what is the recommended baud rate for the SPI bus? 

On the DK I don't get the blip at all. The signal does look a bit choppier as well. I see on other threads there are resistors you're supposed to remove for that functionality to work, is that true of the 833-DK?

[Alex Ross]

I've whipped up the demo SPI/SPIM examples for use with the 833 board and there was no activity at all on any of the lines. Is there a better demo specifically for the 833 that will work? Maybe a hex so that I can verify both and rule out my system? This was two 833 DK boards talking to each. It's really starting to feel like version 17 doesn't work with SPI/833. I've tried a lot of variations of the example code and still nothing. 

[Alex Ross]

Here's the code referenced from my last point. My best guess is I'm missing something in sdk_config.h SPI Master_Slave.zip

[Alex Ross]

Found the probem. Looking closer at the pins, they needed to be offset onto a different port.

#define CS_PIN NRF_GPIO_PIN_MAP(0,12)
#define MISO_PIN NRF_GPIO_PIN_MAP(0,4)
#define MOSI_PIN NRF_GPIO_PIN_MAP(1,8)
#define CLK_PIN NRF_GPIO_PIN_MAP(1,9)