Trouble: TWI(I2C) stops at the function of i2c_reg_read_byte On nRF9160 DK. Why?

[Yusuke]

I'm trying to have nRF9160 DK communicate with an external accelerometer. 

nRF9160 stop working at the function of i2c_reg_read_byte in the code below.

Does anybody give any advice?

<main.c>

#include <nrf9160.h>
#include <zephyr.h>
#include <misc/printk.h>
#include <i2c.h>
#include <string.h>
#include <stdlib.h>
#include <math.h>

#define I2C_ACCEL_WRITE_ADDR 0x32
#define I2C_ACCEL_READ_ADDR 0x33

struct device *i2c_accel;
uint8_t WhoAmI = 0u;

uint8_t init_accelerometer(){
    i2c_accel = device_get_binding("I2C_2");
    if (!i2c_accel) {
		printk("error\r\n");
        return -1;
	} else  {
        i2c_configure(i2c_accel, I2C_SPEED_SET(I2C_SPEED_STANDARD));
        return 0;
    }
}

void main(void)
{
    printk("Hello, World!\r\n");
    init_accelerometer();

	while (1) {
        printk("loop head\r\n");

        if (i2c_reg_read_byte(i2c_accel, I2C_ACCEL_READ_ADDR, 0x0F, WhoAmI) != 0) { // stop wroking at this line
                printk("Error on i2c_read()\n");
        } else {
                printk("no error\r\n");
        }

        printk("WhoAmI = %u\r\n", WhoAmI);
        printk("enter sleep\r\n");
        k_sleep(1000);
	}
}

<prj.conf>

CONFIG_TRUSTED_EXECUTION_SECURE=y
# needed to get the NRF_UARTE2 define
CONFIG_UART_2_NRF_UARTE=y

CONFIG_TRUSTED_EXECUTION_NONSECURE=y
CONFIG_SERIAL=y
CONFIG_UART_INTERRUPT_DRIVEN=y

CONFIG_I2C=y
CONFIG_I2C_NRFX=y
CONFIG_I2C_2=y
CONFIG_I2C_INIT_PRIORITY=60

<overlay file>

/* needed to get the NRF_UARTE2 defined */
&uart2 {
	current-speed = <1000000>;
	status = "ok";
	tx-pin = <18>;
	rx-pin = <17>;
	rts-pin = <19>;
	cts-pin = <21>;
};

&i2c2 {
	status = "ok";
	sda-pin = <10>;
	scl-pin = <11>;
	clock-frequency = <100000>; 
};

UPDATE:

<printk>
***** Booting Zephyr OS v1.13.99-ncs2 *****
Hello, World!
loop head
// stack here