Hi
I am trying to use the TWI on nrf52840 but i am unable to get it to work. its getting stuck somewhere. I dont have a logic analyzer so i am unable to check if the signal are coming or not. I am able to use the I2C with apache mynewt so i dont think its the hardware problem. i have doubled checked the pin assignments for SCL and SDA as well. I have attached the code. Please help me out.
Output on the terminal:
<info> app: TWI scanner started
<info> app: Function return code: NRF_SUCCESS
<info> app: after twi_init
/**
* Copyright (c) 2016 - 2018, 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.
*
*/
/** @file
* @defgroup tw_scanner main.c
* @{
* @ingroup nrf_twi_example
* @brief TWI Sensor Example main file.
*
* This file contains the source code for a sample application using TWI.
*
*/
#include <stdio.h>
#include "boards.h"
#include "app_util_platform.h"
#include "app_error.h"
#include "nrf_drv_twi.h"
#include "nrf_log.h"
#include "nrf_log_ctrl.h"
#include "nrf_log_default_backends.h"
/* TWI instance ID. */
#define TWI0_ENABLED 1
#define TWI_INSTANCE_ID 0
#define MPU9250_ADDRESS 0x68
#define WHO_AM_I_MPU9250 0x75 // Should return 0x71
#define CORRECT_RETURN 0x71
/* TWI instance. */
static const nrf_drv_twi_t m_twi = NRF_DRV_TWI_INSTANCE(TWI_INSTANCE_ID);
/**
* @brief TWI initialization.
*/
void twi_init (void)
{
ret_code_t err_code;
const nrf_drv_twi_config_t twi_config = {
.scl = I2C_0_PIN_SCL,
.sda = I2C_0_PIN_SDA,
.frequency = I2C_0_FREQ_KHZ,
.interrupt_priority = APP_IRQ_PRIORITY_HIGH,
.clear_bus_init = false
};
err_code = nrf_drv_twi_init(&m_twi, &twi_config, NULL, NULL);
char const * p_desc = nrf_strerror_find(err_code);
if (p_desc == NULL)
{
/* No human readable form found */
NRF_LOG_INFO("Function return code: UNKNOWN (%x)", err_code);
}
else
{
/* Nice - mnemonic like - human readable form found */
NRF_LOG_INFO("Function return code: %s", p_desc);
}
APP_ERROR_CHECK(err_code);
nrf_drv_twi_enable(&m_twi);
}
/*
* function to read sensor registers.
*/
ret_code_t read_register(nrf_drv_twi_t twi_instance, uint8_t device_addr, uint8_t register_addr, uint8_t *p_data, uint8_t bytes, bool no_stop)
{
ret_code_t err_code;
err_code = nrf_drv_twi_tx(&twi_instance, device_addr, ®ister_addr, 1, no_stop);
APP_ERROR_CHECK(err_code);
if(err_code != NRF_SUCCESS) {
return err_code;
}
err_code = nrf_drv_twi_rx(&twi_instance, device_addr, p_data, bytes);
return err_code;
}
/**
* @brief Function for main application entry.
*/
int main(void)
{
ret_code_t err_code;
//uint8_t address;
uint8_t sample_data;
bool detected_device = false;
APP_ERROR_CHECK(NRF_LOG_INIT(NULL));
NRF_LOG_DEFAULT_BACKENDS_INIT();
NRF_LOG_INFO("TWI scanner started");
NRF_LOG_FLUSH();
twi_init();
NRF_LOG_INFO("after twi_init");
NRF_LOG_FLUSH();
err_code = read_register(m_twi, MPU9250_ADDRESS, WHO_AM_I_MPU9250, &sample_data, sizeof(sample_data), 0);
char const * p_desc = nrf_strerror_find(err_code);
if (p_desc == NULL)
{
/* No human readable form found */
NRF_LOG_INFO("Function read_register code: UNKNOWN (%x)", err_code);
}
else
{
/* Nice - mnemonic like - human readable form found */
NRF_LOG_INFO("Function read_register code: %s", p_desc);
}
NRF_LOG_FLUSH();
if (err_code == NRF_SUCCESS)
{
detected_device = true;
NRF_LOG_INFO("should be 0x71 but is 0x%02X", sample_data);
}else{
NRF_LOG_INFO("Failed!\n");
}
NRF_LOG_FLUSH();
if (!detected_device)
{
NRF_LOG_INFO("No device was found.");
NRF_LOG_FLUSH();
}
while (true)
{
/* Empty loop. */
}
}
/** @} */
Thanks.
