nRF51822 Radio Transmitter & Receiver with SPI.

Question

Hello,

I am working on a project which requires radio transmitter and receiver to work in sync with the SPI. So the setup is as follows the Transmitter transmits a signal to the receiver and the receiver sends the RSSI(Received Signal Strength Indicator) to the transmitter using SPI. I have merged the two codes for the radio transmitter-receiver and the spi, spis code from the SDK 12.3. When I run the two codes in two different development kits, they are transmitting and receiving the rssi but when I connect the two Development kits with the (using male to male wires)SPI connection i.e SCK - SCK, MISO- MISO, MOSI- MOSI, SS-SS pins of the two development kit, It no longer transmits and receives any signal. I know that it is receiving the signal because it glows the leds. Also, the log is not working for this code and I have no idea why I have also included the following code in the sdk_config file:-

#ifdef NRF_LOG_ENABLED
#define NRF_LOG_ENABLED 1
#endif

The transmitter code :-

/**
 * Copyright (c) 2015 - 2017, Nordic Semiconductor ASA
 * 
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 * 
 * 1. Redistributions of source code must retain the above copyright notice, this
 *    list of conditions and the following disclaimer.
 * 
 * 2. Redistributions in binary form, except as embedded into a Nordic
 *    Semiconductor ASA integrated circuit in a product or a software update for
 *    such product, must reproduce the above copyright notice, this list of
 *    conditions and the following disclaimer in the documentation and/or other
 *    materials provided with the distribution.
 * 
 * 3. Neither the name of Nordic Semiconductor ASA nor the names of its
 *    contributors may be used to endorse or promote products derived from this
 *    software without specific prior written permission.
 * 
 * 4. This software, with or without modification, must only be used with a
 *    Nordic Semiconductor ASA integrated circuit.
 * 
 * 5. Any software provided in binary form under this license must not be reverse
 *    engineered, decompiled, modified and/or disassembled.
 * 
 * THIS SOFTWARE IS PROVIDED BY NORDIC SEMICONDUCTOR ASA "AS IS" AND ANY EXPRESS
 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY, NONINFRINGEMENT, AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL NORDIC SEMICONDUCTOR ASA OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
 * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 * 
 */

#include <stdint.h>
#include <stdbool.h>
#include <stdio.h>
#include "radio_config.h"
#include "app_timer.h"
#include "bsp.h"
#include "nrf_gpio.h"
#include "sdk_config.h"
#include "nrf_drv_spis.h"
#include "nrf_gpio.h"
#include "boards.h"
#include "app_error.h"
#include "nordic_common.h"
#include "nrf_error.h"
#include <string.h>
#define NRF_LOG_MODULE_NAME "APP"
#include "nrf_log.h"
#include "nrf_log_ctrl.h"


#define APP_TIMER_PRESCALER      0                           /**< Value of the RTC1 PRESCALER register. */
#define APP_TIMER_OP_QUEUE_SIZE  2                           /**< Size of timer operation queues. */

static uint32_t                   packet;                    /**< Packet to transmit. */

#define SPIS_INSTANCE 1 /**< SPIS instance index. */
static const nrf_drv_spis_t spis = NRF_DRV_SPIS_INSTANCE(SPIS_INSTANCE);/**< SPIS instance. */

#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. */

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


/**@brief Function for sending packet.
 */
void send_packet()
{
    // send the packet:
    NRF_RADIO->EVENTS_READY = 0U;
    NRF_RADIO->TASKS_TXEN   = 1;

    while (NRF_RADIO->EVENTS_READY == 0U)
    {
        // wait
    }
    NRF_RADIO->EVENTS_END  = 0U;
    NRF_RADIO->TASKS_START = 1U;

    while (NRF_RADIO->EVENTS_END == 0U)
    {
        // wait
    }

    uint32_t err_code = bsp_indication_set(BSP_INDICATE_SENT_OK);
    NRF_LOG_INFO("The packet was sent\r\n");
    APP_ERROR_CHECK(err_code);

    NRF_RADIO->EVENTS_DISABLED = 0U;
    // Disable radio
    NRF_RADIO->TASKS_DISABLE = 1U;

    while (NRF_RADIO->EVENTS_DISABLED == 0U)
    {
        // wait
    }
}


/**@brief Function for handling bsp events.
 */
void bsp_evt_handler(bsp_event_t evt)
{
    uint32_t prep_packet = 0;
    switch (evt)
    {
        case BSP_EVENT_KEY_0:
            /* Fall through. */
        case BSP_EVENT_KEY_1:
            /* Fall through. */
        case BSP_EVENT_KEY_2:
            /* Fall through. */
        case BSP_EVENT_KEY_3:
            /* Fall through. */
        case BSP_EVENT_KEY_4:
            /* Fall through. */
        case BSP_EVENT_KEY_5:
            /* Fall through. */
        case BSP_EVENT_KEY_6:
            /* Fall through. */
        case BSP_EVENT_KEY_7:
            /* Get actual button state. */
            for (int i = 0; i < BUTTONS_NUMBER; i++)
            {
                prep_packet |= (bsp_board_button_state_get(i) ? (1 << i) : 0);
            }
            break;
        default:
            /* No implementation needed. */
            break;
    }
    packet = prep_packet;
}


/**@brief Function for initialization oscillators.
 */
void clock_initialization()
{
    /* Start 16 MHz crystal oscillator */
    NRF_CLOCK->EVENTS_HFCLKSTARTED = 0;
    NRF_CLOCK->TASKS_HFCLKSTART    = 1;

    /* Wait for the external oscillator to start up */
    while (NRF_CLOCK->EVENTS_HFCLKSTARTED == 0)
    {
        // Do nothing.
    }

    /* Start low frequency crystal oscillator for app_timer(used by bsp)*/
    NRF_CLOCK->LFCLKSRC            = (CLOCK_LFCLKSRC_SRC_Xtal << CLOCK_LFCLKSRC_SRC_Pos);
    NRF_CLOCK->EVENTS_LFCLKSTARTED = 0;
    NRF_CLOCK->TASKS_LFCLKSTART    = 1;

    while (NRF_CLOCK->EVENTS_LFCLKSTARTED == 0)
    {
        // Do nothing.
    }
}

/**
 * @brief SPIS user event handler.
 *
 * @param event
 */
void spis_event_handler(nrf_drv_spis_event_t event)
{
    if (event.evt_type == NRF_DRV_SPIS_XFER_DONE)
    {
        spis_xfer_done = true;
        NRF_LOG_INFO(" Transfer completed. Received: %s\r\n",(uint32_t)m_rx_buf);
    }
}

int main(void)
{		
	
		uint32_t err_code = NRF_SUCCESS;

    clock_initialization();
    APP_TIMER_INIT(APP_TIMER_PRESCALER, APP_TIMER_OP_QUEUE_SIZE, NULL);

    err_code = NRF_LOG_INIT(NULL);
    APP_ERROR_CHECK(err_code);

    err_code = bsp_init(BSP_INIT_LED | BSP_INIT_BUTTONS,
                        APP_TIMER_TICKS(100, APP_TIMER_PRESCALER),
                        bsp_evt_handler);
    APP_ERROR_CHECK(err_code);

    // Set radio configuration parameters
    radio_configure();

    // Set payload pointer
    NRF_RADIO->PACKETPTR = (uint32_t)&packet;

    err_code = bsp_indication_set(BSP_INDICATE_USER_STATE_OFF);
    NRF_LOG_INFO("Press Any Button\r\n");
    APP_ERROR_CHECK(err_code);
    // Enable the constant latency sub power mode to minimize the time it takes
    // for the SPIS peripheral to become active after the CSN line is asserted
    // (when the CPU is in sleep mode).
    NRF_POWER->TASKS_CONSTLAT = 1;

    bsp_board_leds_init();

    APP_ERROR_CHECK(NRF_LOG_INIT(NULL));
    NRF_LOG_INFO("SPIS example\r\n");

    nrf_drv_spis_config_t spis_config = NRF_DRV_SPIS_DEFAULT_CONFIG;
    spis_config.csn_pin               = APP_SPIS_CS_PIN;
    spis_config.miso_pin              = APP_SPIS_MISO_PIN;
    spis_config.mosi_pin              = APP_SPIS_MOSI_PIN;
    spis_config.sck_pin               = APP_SPIS_SCK_PIN;

    APP_ERROR_CHECK(nrf_drv_spis_init(&spis, &spis_config, spis_event_handler));

    while (1)
    {
				if (packet != 0)
        {
            send_packet();
            NRF_LOG_INFO("The contents of the package was %u\r\n", (unsigned int)packet);
            packet = 0;
        }
        //NRF_LOG_FLUSH();
        //__WFE();
    
        memset(m_rx_buf, 0, m_length);
        spis_xfer_done = false;

        APP_ERROR_CHECK(nrf_drv_spis_buffers_set(&spis, m_tx_buf, m_length, m_rx_buf, m_length));

        while (!spis_xfer_done)
        {
            __WFE();
        }

        //NRF_LOG_FLUSH();

        bsp_board_led_invert(BSP_BOARD_LED_2);
    }
}

The receiver code:-

/**
 * Copyright (c) 2015 - 2017, Nordic Semiconductor ASA
 * 
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 * 
 * 1. Redistributions of source code must retain the above copyright notice, this
 *    list of conditions and the following disclaimer.
 * 
 * 2. Redistributions in binary form, except as embedded into a Nordic
 *    Semiconductor ASA integrated circuit in a product or a software update for
 *    such product, must reproduce the above copyright notice, this list of
 *    conditions and the following disclaimer in the documentation and/or other
 *    materials provided with the distribution.
 * 
 * 3. Neither the name of Nordic Semiconductor ASA nor the names of its
 *    contributors may be used to endorse or promote products derived from this
 *    software without specific prior written permission.
 * 
 * 4. This software, with or without modification, must only be used with a
 *    Nordic Semiconductor ASA integrated circuit.
 * 
 * 5. Any software provided in binary form under this license must not be reverse
 *    engineered, decompiled, modified and/or disassembled.
 * 
 * THIS SOFTWARE IS PROVIDED BY NORDIC SEMICONDUCTOR ASA "AS IS" AND ANY EXPRESS
 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY, NONINFRINGEMENT, AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL NORDIC SEMICONDUCTOR ASA OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
 * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 * 
 */


#include <stdint.h>
#include <stdbool.h>
#include <stdio.h>
#include "radio_config.h"
#include "nrf_drv_spi.h"
#include "bsp.h"
#include "app_timer.h"
#include "nordic_common.h"
#include "nrf_error.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 APP_TIMER_PRESCALER      0                     /**< Value of the RTC1 PRESCALER register. */
#define APP_TIMER_OP_QUEUE_SIZE  2                     /**< Size of timer operation queues. */

static uint32_t                   packet;              /**< Packet to transmit. */
uint32_t rssi;

#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 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 Function for initialization oscillators.
 */
void clock_initialization()
{
    /* Start 16 MHz crystal oscillator */
    NRF_CLOCK->EVENTS_HFCLKSTARTED = 0;
    NRF_CLOCK->TASKS_HFCLKSTART    = 1;

    /* Wait for the external oscillator to start up */
    while (NRF_CLOCK->EVENTS_HFCLKSTARTED == 0)
    {
        // Do nothing.
    }

    /* Start low frequency crystal oscillator for app_timer(used by bsp)*/
    NRF_CLOCK->LFCLKSRC            = (CLOCK_LFCLKSRC_SRC_Xtal << CLOCK_LFCLKSRC_SRC_Pos);
    NRF_CLOCK->EVENTS_LFCLKSTARTED = 0;
    NRF_CLOCK->TASKS_LFCLKSTART    = 1;

    while (NRF_CLOCK->EVENTS_LFCLKSTARTED == 0)
    {
        // Do nothing.
    }
}


/**@brief Function for reading packet.
 */
uint32_t read_packet()
{
	
		NRF_RADIO->SHORTS |= RADIO_SHORTS_ADDRESS_RSSISTART_Msk;
	
		NRF_RADIO->INTENSET = RADIO_INTENSET_READY_Msk | RADIO_INTENSET_END_Msk | RADIO_INTENSET_DISABLED_Msk;
	
    uint32_t result = 0;

    NRF_RADIO->EVENTS_READY = 0U;
    // Enable radio and wait for ready
    NRF_RADIO->TASKS_RXEN = 1U;

    while (NRF_RADIO->EVENTS_READY == 0U)
    {
        // wait
    }
    NRF_RADIO->EVENTS_END = 0U;
    // Start listening and wait for address received event
    NRF_RADIO->TASKS_START = 1U;

    // Wait for end of packet or buttons state changed
    while (NRF_RADIO->EVENTS_END == 0U)
    {
        // wait
    }

    if (NRF_RADIO->CRCSTATUS == 1U)
    {
        result = packet;
				rssi = NRF_RADIO->RSSISAMPLE;
				
    }
    NRF_RADIO->EVENTS_DISABLED = 0U;
    // Disable radio
    NRF_RADIO->TASKS_DISABLE = 1U;

    while (NRF_RADIO->EVENTS_DISABLED == 0U)
    {
        // wait
    }
    return result;
}

/**
 * @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)
{		
		uint32_t err_code = NRF_SUCCESS;
	
		nrf_gpio_range_cfg_output(21, 24);

    clock_initialization();
    APP_TIMER_INIT(APP_TIMER_PRESCALER, APP_TIMER_OP_QUEUE_SIZE, NULL);

    err_code = NRF_LOG_INIT(NULL);
    APP_ERROR_CHECK(err_code);
    err_code = bsp_init(BSP_INIT_LED, APP_TIMER_TICKS(100, APP_TIMER_PRESCALER), NULL);
    APP_ERROR_CHECK(err_code);

    // Set radio configuration parameters
    radio_configure();
    NRF_RADIO->PACKETPTR = (uint32_t)&packet;

    err_code = bsp_indication_set(BSP_INDICATE_USER_STATE_OFF);
    NRF_LOG_INFO("Wait for first packet\r\n");
    APP_ERROR_CHECK(err_code);
    
    //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   = SPI_SS_PIN;
    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));

		NRF_LOG_FLUSH();
		
    while (1)
    {
				
				uint32_t received = read_packet();

        err_code = bsp_indication_set(BSP_INDICATE_RCV_OK);
        NRF_LOG_INFO("Packet was received\r\n");
        APP_ERROR_CHECK(err_code);

        NRF_LOG_INFO("The contents of the package is %u\r\n", (unsigned int)received);
				NRF_LOG_INFO("The RSSI of the package is %u\r\n", (unsigned int)rssi);
			
				if(rssi>40 && rssi<50)
				{
					nrf_gpio_pin_write(21, 0);
					nrf_gpio_pin_write(22, 0);
					nrf_gpio_pin_write(23, 0);
					nrf_gpio_pin_write(24, 0);
				}
				
				if(rssi>50 && rssi<60)
				{
					nrf_gpio_pin_write(21, 1);
					nrf_gpio_pin_write(22, 0);
					nrf_gpio_pin_write(23, 0);
					nrf_gpio_pin_write(24, 0);
				}
				
				if(rssi>60 && rssi<70)
				{ 
					nrf_gpio_pin_write(21, 1);
					nrf_gpio_pin_write(22, 1);
					nrf_gpio_pin_write(23, 0);
					nrf_gpio_pin_write(24, 0);
				}
			
				if(rssi>70 && rssi<80)
				{
					nrf_gpio_pin_write(21, 1);
					nrf_gpio_pin_write(22, 1);
					nrf_gpio_pin_write(23, 1);
					nrf_gpio_pin_write(24, 0);
				}
       
				
        // Reset rx buffer and transfer done flag
        memset(m_rx_buf, 0, m_length);
        spi_xfer_done = false;

        APP_ERROR_CHECK(nrf_drv_spi_transfer(&spi, m_tx_buf, m_length, m_rx_buf, m_length));

        while (!spi_xfer_done)
        {
            __WFE();
					spi_xfer_done = true;
        }

        //NRF_LOG_FLUSH();

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

I would really appreciate if you could help me run this code properly.

Thank You.