Hello. I have a nRF52832 DK and I'm trying to modify the SPI example code found here:
/nRF5_SDK_15.0.0/nRF5_SDK_15.0.0_a53641a/examples/peripheral/spi
I'm using the nRF52832 DK as the master and a digital potentiometer (MCP4131) as the slave, and Netbeans 8.2 as my IDE.
I want to be able to read and write to registers as well as perform commands as described in section 7 of the MCP4131 datasheet.
I've been able to send the "Nordic" string on the MOSI bus that I read on an oscilloscope. However, I'm struggling to write hexadecimal values to the following function:
<APP_ERROR_CHECK(nrf_drv_spi_transfer(&spi, m_tx_buf, m_length, m_rx_buf, m_length));>
I've tried modifying the value of TEST_STRING from "Nordic" to various hexadecimal formats such as 0x80, %80x, 0X80, "0x80", etc. but I get various errors when I try to do this.
Shouldn't I be able to store a hex value in a static uint8_t value? I feel like I'm missing something obvious here.
Any help would be greatly appreciated! Here is the complete example code for reference:
<
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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 "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,
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_init(BSP_INIT_LEDS);
APP_ERROR_CHECK(NRF_LOG_INIT(NULL));
NRF_LOG_DEFAULT_BACKENDS_INIT();
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, NULL));
NRF_LOG_INFO("SPI example started.");
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));
//NRF_DRV_SPI_XFER_TX(m_tx_buf, m_length);
while (!spi_xfer_done)
{
__WFE();
}
NRF_LOG_FLUSH();
bsp_board_led_invert(BSP_BOARD_LED_0);
nrf_delay_us(1000000);
}
}.