Hello DevZone,
I am doing a simple test for SPI communication between nRF52840 DK(SPI master) and Arduino UNO(slave).
The Nordic program is based on SDK 14.2.0 spi example, I only change the TEST_STRING from "Nordic" to "N" and PIN number according to Arduino PIN map.
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* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without modification,
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*
* 1. Redistributions of source code must retain the above copyright notice, this
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*
* 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.
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* 5. Any software provided in binary form under this license must not be reverse
* engineered, decompiled, modified and/or disassembled.
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* THIS SOFTWARE IS PROVIDED BY NORDIC SEMICONDUCTOR ASA "AS IS" AND ANY EXPRESS
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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>
#include "nrf_log.h"
#include "nrf_log_ctrl.h"
#include "nrf_log_default_backends.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 TEST_STRING "N"
static uint8_t m_tx_buf[] = {'N'}; /**< TX buffer. */
static uint8_t m_rx_buf[2]; /**< 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,
void * p_context)
{
spi_xfer_done = true;
NRF_LOG_INFO("Transfer completed.");
if (m_rx_buf[0] != 0)
{
NRF_LOG_INFO(" Received:");
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_DEFAULT_BACKENDS_INIT();
NRF_LOG_INFO("SPI example.");
nrf_drv_spi_config_t spi_config = NRF_DRV_SPI_DEFAULT_CONFIG;
spi_config.ss_pin = 44; //SPI_SS_PIN;
spi_config.miso_pin = 46; //SPI_MISO_PIN;
spi_config.mosi_pin = 45; //SPI_MOSI_PIN;
spi_config.sck_pin = 47; //SPI_SCK_PIN;
spi_config.irq_priority = APP_IRQ_PRIORITY_LOW;
spi_config.orc = 0xCC;
spi_config.frequency = NRF_DRV_SPI_FREQ_500K;
spi_config.mode = NRF_DRV_SPI_MODE_0;
spi_config.bit_order = NRF_DRV_SPI_BIT_ORDER_MSB_FIRST;
APP_ERROR_CHECK(nrf_drv_spi_init(&spi, &spi_config, spi_event_handler, NULL));
while (1)
{
// 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();
}
NRF_LOG_FLUSH();
bsp_board_led_invert(BSP_BOARD_LED_0);
nrf_delay_ms(200);
}
}
and a Arduino slave example code:
// what to do with incoming data
volatile byte command = 0;
int select_slave = 0; //1: selected, 2: not selected
void setup (void)
{
Serial.begin (9600);
Serial.println ("This is SPI slave test");
// have to send on master in, *slave out*
pinMode(MISO, OUTPUT);
// turn on SPI in slave mode
SPCR |= _BV(SPE);
// turn on interrupts
SPCR |= _BV(SPIE);
} // end of setup
// SPI interrupt routine
ISR (SPI_STC_vect)
{
byte c = SPDR;
if(command == 0)
{
SPDR = 0;
}
else
{
SPDR = c;
Serial.print ("Rx is:");
Serial.println (c, DEC);
Serial.print ("Tx is:");
Serial.println (c, DEC);
}
} // end of interrupt service routine (ISR) SPI_STC_vect
void loop (void)
{
// if SPI not active, clear current command
if (digitalRead (SS) == HIGH)
{
command = 0;
if(select_slave!=2)
{ Serial.println("Slave is not selected");
select_slave = 2;}
}
else
{
command = 1;
if(select_slave!=1)
{ Serial.println("**Slave is selected");
select_slave = 1;}
}
} // end of loop
As I set SPDR to the value Arduino received, what I expect is Nordic should receive the same value it send to Arduino...
The result is: Sending data from Nordic to Arduino seems OK. However, Nordic receives the strange response...
Is it possible to test my sample code in your side? Very appreciate if you can verify my test sample and find the root cause of the problem.
