Custom NRF52832 + LIS2DH12 accelerometer but always get '0'

Question

I got a nrf52832 custom board to communicate with LIS2DH12 accelerometer by I2C(TWI). 
 I edited part of the code from "twi_sensor" project in NRF5_SDK version 17.0. 
 I tried to read the "x_out_low " byte from LIS2DH12, but always get zero. 
 
 Here's my schematic diagram:

Here's my code: 
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/** @file
 * @defgroup tw_sensor_example 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 "app_error.h"
#include "app_util_platform.h"
#include "boards.h"
#include "nrf_delay.h"
#include "nrf_drv_twi.h"
#include <stdio.h>

#include "nrf_log.h"
#include "nrf_log_ctrl.h"
#include "nrf_log_default_backends.h"

/* TWI instance ID. */
#define TWI_INSTANCE_ID 0

#define ACC_ADDR (0x33U >> 1)
#define X_OUT_L 0x28
#define SCL_PIN 5
#define SDA_PIN 2

/* Indicates if operation on TWI has ended. */
static volatile bool m_xfer_done = false;

/* TWI instance. */
static const nrf_drv_twi_t m_twi = NRF_DRV_TWI_INSTANCE(TWI_INSTANCE_ID);

/* Buffer for samples read from temperature sensor. */
static uint8_t m_sample;

/**
 * @brief Function for setting active mode on MMA7660 accelerometer.
 */
void ACC_set_mode(void) {
 ret_code_t err_code;

 // set data rate to 100 Hz
 uint8_t CTRL_REG1[] = {0x20, 0x5F};
 // set full-scale to +/- 2g
 uint8_t CTRL_REG4[] = {0x23, 0x80};
 // set FIFO to stream mode
 uint8_t FIFO_CTRL[] = {0x2E, 0x80};

 err_code = nrf_drv_twi_tx(&m_twi, ACC_ADDR, CTRL_REG1, sizeof(CTRL_REG1), false);
 APP_ERROR_CHECK(err_code);
 while (m_xfer_done == false);

 m_xfer_done = false;
 err_code = nrf_drv_twi_tx(&m_twi, ACC_ADDR, CTRL_REG4, sizeof(CTRL_REG4), false);
 APP_ERROR_CHECK(err_code);
 while (m_xfer_done == false);

 m_xfer_done = false;
 err_code = nrf_drv_twi_tx(&m_twi, ACC_ADDR, FIFO_CTRL, sizeof(FIFO_CTRL), false);
 APP_ERROR_CHECK(err_code);
 while (m_xfer_done == false);
}

/**
 * @brief Function for handling data from temperature sensor.
 *
 * @param[in] temp Temperature in Celsius degrees read from sensor.
 */
__STATIC_INLINE void data_handler(uint8_t temp) {
 printf("data: %d
", temp);
}

/**
 * @brief TWI events handler.
 */
void twi_handler(nrf_drv_twi_evt_t const *p_event, void *p_context) {
 switch (p_event->type) {
 case NRF_DRV_TWI_EVT_DONE:
 if (p_event->xfer_desc.type == NRF_DRV_TWI_XFER_RX) {
 data_handler(m_sample);
 }
 m_xfer_done = true;
 break;
 default:
 break;
 }
}

/**
 * @brief UART initialization.
 */
void twi_init(void) {
 ret_code_t err_code;

 const nrf_drv_twi_config_t twi_acc_config = {
 .scl = SCL_PIN,
 .sda = SDA_PIN,
 .frequency = NRF_DRV_TWI_FREQ_100K,
 .interrupt_priority = APP_IRQ_PRIORITY_HIGH,
 .clear_bus_init = false};

 err_code = nrf_drv_twi_init(&m_twi, &twi_acc_config, twi_handler, NULL);
 APP_ERROR_CHECK(err_code);

 nrf_drv_twi_enable(&m_twi);
}

/**
 * @brief Function for reading data from temperature sensor.
 */
static void read_sensor_data() {
 printf("READING......
");
 uint8_t addr8 = X_OUT_L;
 m_xfer_done = false;
 ret_code_t err_code = nrf_drv_twi_tx(&m_twi, ACC_ADDR, &addr8, 1, true);
 APP_ERROR_CHECK(err_code);
 while (m_xfer_done == false);

 err_code = nrf_drv_twi_rx(&m_twi, ACC_ADDR, &m_sample, sizeof(m_sample));
 APP_ERROR_CHECK(err_code);
 if(m_sample != 0){
 nrf_gpio_pin_toggle(LED_1);
 printf("read: %d
", m_sample);
 }
}

/**
 * @brief Function for main application entry.
 */
int main(void) {
 APP_ERROR_CHECK(NRF_LOG_INIT(NULL));
 NRF_LOG_DEFAULT_BACKENDS_INIT();

 twi_init();

 nrf_gpio_cfg_input(3, NRF_GPIO_PIN_PULLUP);
 nrf_gpio_cfg_output(4);
 nrf_gpio_pin_write(4, 1);
 nrf_gpio_cfg_output(8);
 nrf_gpio_pin_write(8, 1);
 nrf_gpio_cfg_output(LED_1);
 ACC_set_mode();

 while (true) {
 nrf_delay_ms(500);

 do {
 __WFE();
 } while (m_xfer_done == false);
 
 // to confirm everything is still working
 nrf_gpio_pin_toggle(LED_1);
 read_sensor_data();
 }
}

/** @} */ 
 
 Feel free to tell me if you need more information. 
 Any recommendation will be highly appreciated. Thank you very much!!

hmolesworth · Answer

As you know, " If the SA0 pad is connected to the voltage supply, LSb is ‘1’ (address 0011001b), else if the SA0 pad is connected to ground, the LSb value is ‘0’ (address 0011000b) ." This line doesn't do what is intended: #define ACC_ADDR (0x33U >> 1) That '1' LS bit has just been discarded; this is often confusing with i2c, is the 7-bit address left- or right-shifted or not and the answer depends on the library. Check the function to see whether it actually expects an un-shifted address. I would try this: #define ACC_ADDR (0x33U << 1) The red LED works fine off a CR2032, but to get enough voltage for blue and green LEDs when the battery is low try adding another i/o pin and driving a capacitor with a diode clamp to provide voltage boost; the nRF52832 4-output PWM circuit is ideal for this - red/green/blue/boost, a common application made easy.

Leo Yang · Answer

Finally, I figured it out. I forgot to set the FIFO enable bit in CTRL_REG5....

Custom NRF52832 + LIS2DH12 accelerometer but always get '0'

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