Not able to see log output in COM port for SPI.

[BeaconBLE]

Hello,

I am using NRF51 DK for developing an application. I tried running the default SPI example in the SDK 12.3 which uses the spi and spis example. The location of those examples are SDK ->examples -> peripheral -> spi & spis. When I run these examples in two different boards I can see the led blinking showing that the spi transfer is completed but when I connect my COM port to Putty software I am not seeing any output in the log. I want to connect nRF51822 boards using SPI but I cannot figure out if they are working or not without the log. If you can please let me know how do I make the log work for this specific example.

Thank You.

[Jørgen Holmefjord]

By default, the logger module is not enabled in the examples. You need to set the following define in sdk_config.h:

#define NRF_LOG_ENABLED 1

Hein said:

Not sure about the 51, but in the 52 you can not run the SPI0 and UART0 at the same time, are they both configured for instance 0 ?

This is not correct, UART does not share instance with other serial devices. Only SPI/SPIM/SPIS/TWI/TWIM/TWIS share base address.

[Jørgen Holmefjord]

Unless you are using the SD Card/FatFS library, I would recommend that you control SS pin manually, rather than modifying the driver as suggested in the link.

You cannot transmitt data from more than one device at a time on a single bus, then you need to setup multiple SPI instances. nRF51 support two SPI master instances. 

The simples solution would be to configure the transmitter as a SPI master device and the 4 others as SPI slave. You can then set SS pin manually for each device and transmitt/receive from that device. Then move to the next device.

[BeaconBLE]

So for changing the SS pin manually do I not do the changes in the nrf_drv_spi.h and nrf_drv_spi.c file and what other changes do I have to do for it to work. Also, when 4 slaves are transmitting how do I manage the timing because they cannot transmit simultaneously right. Is there a way to know whether the other slave is currently using the SPI pin or not?

Thank You.

[Jørgen Holmefjord]

Yes, no changes to the nrf_drv_spi files. You simply set and clear the SS pin in use with GPIO functions nrf_gpio_pin_set/clear(). Note that you have to setup the SS pins using nrf_gpio_cfg_output() first.

The master is always the one initiating a transfer on the SPI bus. The slaves can not start transmitting by itself. You will have full control over which slave device is transferring in the master application.

[BeaconBLE]

Hello,

I am really sorry for the trouble, I am a beginner, if you could please help me with a gist of code changes that I have to do in the SDK 12.3 spi and spis example that would be great.

Thank You.

[Jørgen Holmefjord]

You should not have to modify the SPIS example, the slaves does not care which device it is interfaced by.

I have attached main.c file that show how you can interface 4 different slaves that is connected to the same SPI instace for SPI master example: 

Fullscreen main.c Download

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#include "nrf_drv_spi.h"
#include "app_util_platform.h"
#include "nrf_gpio.h"
#include "nrf_delay.h"
#include "boards.h"
#include "app_error.h"
#include <string.h>
#define NRF_LOG_MODULE_NAME "APP"
#include "nrf_log.h"
#include "nrf_log_ctrl.h"

#define SPI_INSTANCE  0 /**< SPI instance index. */
static const nrf_drv_spi_t spi = NRF_DRV_SPI_INSTANCE(SPI_INSTANCE);  /**< SPI instance. */
static volatile bool spi_xfer_done;  /**< Flag used to indicate that SPI instance completed the transfer. */

#define NUMBER_OF_SLAVES 4
uint8_t ss_pin_numbers[NUMBER_OF_SLAVES]	= {12, 13, 14, 15};

#define TEST_STRING "Nordic"
static uint8_t       m_tx_buf[] = TEST_STRING;           /**< TX buffer. */
static uint8_t       m_rx_buf[sizeof(TEST_STRING) + 1];    /**< RX buffer. */
static const uint8_t m_length = sizeof(m_tx_buf);        /**< Transfer length. */

/**
 * @brief SPI user event handler.
 * @param event
 */
void spi_event_handler(nrf_drv_spi_evt_t const * p_event)
{
    spi_xfer_done = true;
    NRF_LOG_INFO("Transfer completed.\r\n");
    if (m_rx_buf[0] != 0)
    {
        NRF_LOG_INFO(" Received: \r\n");
        NRF_LOG_HEXDUMP_INFO(m_rx_buf, strlen((const char *)m_rx_buf));
    }
		
}

int main(void)
{
    bsp_board_leds_init();

    APP_ERROR_CHECK(NRF_LOG_INIT(NULL));

    NRF_LOG_INFO("SPI example\r\n");

    nrf_drv_spi_config_t spi_config = NRF_DRV_SPI_DEFAULT_CONFIG;
    spi_config.ss_pin   = NRF_DRV_SPI_PIN_NOT_USED;
    spi_config.miso_pin = SPI_MISO_PIN;
    spi_config.mosi_pin = SPI_MOSI_PIN;
    spi_config.sck_pin  = SPI_SCK_PIN;
    APP_ERROR_CHECK(nrf_drv_spi_init(&spi, &spi_config, spi_event_handler));

		// Configuring GPIOs as output for all SPI SS pins
		for(uint8_t i = 0; i < NUMBER_OF_SLAVES; i++)
		{
				nrf_gpio_cfg_output(ss_pin_numbers[i]);
		}
		
    while (1)
    {
        // Reset rx buffer and transfer done flag
				for(uint8_t i = 0; i < NUMBER_OF_SLAVES; i++)
				{
						memset(m_rx_buf, 0, m_length);
						spi_xfer_done = false;

						nrf_gpio_pin_clear(ss_pin_numbers[i]); // Assert SS pin for current slave to initiate transfer
					
						APP_ERROR_CHECK(nrf_drv_spi_transfer(&spi, m_tx_buf, m_length, m_rx_buf, m_length));

						while (!spi_xfer_done)
						{
								__WFE();
						}
						nrf_gpio_pin_set(ss_pin_numbers[i]); // De-assert SS pin for current slave to complete transfer
				}
        

        NRF_LOG_FLUSH();

        bsp_board_led_invert(BSP_BOARD_LED_0);
        nrf_delay_ms(200);
    }
}

The slave SS pins should be connected to GPIO P0.12-P0.15.