Problems with TWI when using Bluetooth LE simultaneously (taking wrong data from TWI when enable BLE)

[jswcomkr]

Hi. I'm developing IMU system for multiple purpose using ICM20948 & nRF52832.

But there are problems on TWI communications when using BLE simultaneously.

If not use BLE, all the data comes from IMU sensor is pretty well as shown below:

Small deviation is deliberate data for test purpose.

But after enable BLE, wrong data comes out from ICM20948 sensor as below. It is connected with TWI lines.

 Only X-Axis are normal data. I attached source codes which get or send data to ICM20948 sensor.

/*
 *  Roverdyn I2C(TWI) Library
 *  Created at Jan. 14, 2020
 *  Author : Seonguk Jeong
 *  Copyright to 2019 Seonguk Jeong. All rights reserved.
 *  Contact : [email protected]
 */

#include "Wire.h"

void _Wire::begin(){
	// I2C 통신을 활성화 시키는 함수
	// 기본 통신 속도는 400kHz
	// 기본 설정 핀 : SCL(12번), SDA(11번)
	// 설정 핀은 Wire.h 에서 바꿀 수 있음

	// I2C 통신 비활성화
	NRF_TWI0->ENABLE = 0;

	// SCL/SDA핀 설정
	NRF_TWI0->PSELSCL = pinSCL;
	NRF_TWI0->PSELSDA = pinSDA;

	// 통신 주파수 설정(400kHz)
	NRF_TWI0->FREQUENCY = 0x06680000;

	// 인터럽트 비활성화
	NRF_TWI0->INTENCLR = 0x044286;

	// I2C 통신 활성화
	NRF_TWI0->ENABLE = 5;

	// 이벤트 초기화
	NRF_TWI0->EVENTS_RXDREADY = 0;
	NRF_TWI0->EVENTS_TXDSENT = 0;
}

uint8_t _Wire::requestFrom(uint8_t address, uint8_t bytes){
	// Slave device로부터 데이터를 요청하는 함수
	uint8_t recvLength = 0;

	// 통신 주소 및 Read 신호 송신
	NRF_TWI0->ADDRESS = address;

	NRF_TWI0->TASKS_STARTRX = 1;

	for(uint8_t i=0;i<bytes;i++){
		// Byte Boundary 이벤트 확인
		while(!NRF_TWI0->EVENTS_BB){}
		NRF_TWI0->EVENTS_BB = 0;

		// 마지막 데이터가 오면 STOP
		if(i == (bytes - 1)){
			NRF_TWI0->TASKS_STOP = 1;
		}

		// 데이터 읽기
		while(!NRF_TWI0->EVENTS_RXDREADY){}
		NRF_TWI0->EVENTS_RXDREADY = 0;
		rxBuffer[i] = NRF_TWI0->RXD;
	}

	return recvLength;
}

void _Wire::beginTransmission(uint8_t address){
	// TWI 데이터 전송을 시작하는 함수
	NRF_TWI0->ENABLE = 5;
	NRF_TWI0->ADDRESS = address;
	NRF_TWI0->TASKS_STARTTX = 1;
	memset(&rCount, 0x00, sizeof(rCount));
	memset(&rxBuffer, 0x00, sizeof(rxBuffer));
	rCount = 0;
}

uint8_t _Wire::endTransmission(bool toggle){
	// TWI 통신 종료 함수
	uint8_t err_code = 0;
	if(toggle){
		if(!NRF_TWI0->EVENTS_STOPPED){NRF_TWI0->TASKS_STOP = 1;}
		while(!NRF_TWI0->EVENTS_STOPPED){}
		NRF_TWI0->EVENTS_STOPPED = 0;
		err_code = 1;
	}
	NRF_TWI0->ENABLE = 0;
	return err_code;
}

uint8_t _Wire::write(uint8_t data){
	NRF_TWI0->TXD = data;
	while(!NRF_TWI0->EVENTS_TXDSENT){}
	NRF_TWI0->EVENTS_TXDSENT = 0;
	return 0;
}

uint8_t _Wire::available(){
	return 0;
}

uint8_t _Wire::read(){
	static uint8_t output = 0;
	output = rxBuffer[rCount];
	rCount++;
	return output;
}

void _Wire::setClock(uint32_t frequency){
	// I2C 통신 속도를 설정하는 함수
	// 별도로 함수를 호출하지 않을 경우 400kHz로 동작

	switch(frequency){
	case 100000:
		// 100Khz로 설정 시
		NRF_TWI1->FREQUENCY = 0x01980000;
		break;
	case 250000:
		// 250Khz로 설정 시
		NRF_TWI1->FREQUENCY = 0x04000000;
		break;
	case 400000:
		// 400Khz로 설정 시
		NRF_TWI1->FREQUENCY = 0x06680000;
		break;
	default:
		NRF_TWI1->FREQUENCY = 0x06680000;
		break;
	}
}

/*
 *  Roverdyn UART Library
 *  Created at Mar. 6, 2020
 *  Author : Seonguk Jeong
 *  Copyright to 2020 Seonguk Jeong. All rights reserved.
 *  Contact : [email protected]
 */

#include "ICM20948.h"
#include <SEGGER_RTT.h>

_Wire Wire;
extern _Serial Serial;

uint8_t _ICM20948::Init(){
	uint8_t err_code = 0;

	// TWI 통신 초기화 및 시작
	Wire.begin();

	// ICM20948 초기화
	writeData(DEVICE_ID, REG_BANK_SEL, 0x00);
	writeData(DEVICE_ID, PWR_MGMT_1, 0x80);
	nrf_delay_ms(100);
	writeData(DEVICE_ID, PWR_MGMT_1, 0x01);
	writeData(DEVICE_ID, PWR_MGMT_2, 0x00);

	// 바이패스 모드 설정
	writeData(DEVICE_ID, INT_PIN_CFG, (0x01 << 1));

	// Device ID 읽기
	// 제대로 연결이 되어 있지 않으면 0x01(에러)를 리턴
	if(getDeviceId() != 234){
		return ROVERDYN_ERROR_NO_DATA;
	}
	if(getMagId() != 0x09){
		return ROVERDYN_ERROR_NO_DATA;
	}
/*
	// Sample rate
	writeData(DEVICE_ID, REG_BANK_SEL, 0x02);
	writeData(DEVICE_ID, GYRO_SMPLRT_DIV, 0x01);
	writeData(DEVICE_ID, ACCEL_SMPLRT_DIV_2, 0x01);
*/
	// 자이로스코프 설정
	setCfgGyro(DLPF_GYRO_6HZ, GYRO_RANGE_1000DPS, GYRO_AVG_1X, true);

	// 가속도 센서 설정
	setCfgAcc(DLPF_ACC_6HZ, ACCEL_RANGE_2G, ACCEL_AVG_4X, true);

	// 지자기 센서 설정
	setMagMode(MAG_CONTINUOUS_MODE2);

	// 온도 센서 설정
	setCfgTemp(TEMP_DLPF_34HZ);

	return err_code;
}

uint8_t _ICM20948::writeData(uint8_t device, uint8_t addr, uint8_t data){
	// 레지스터에 값을 쓰는 함수
	uint8_t err_code = 0;

	// 통신 시작
	Wire.beginTransmission(device);
	Wire.write(addr);
	Wire.write(data);
	Wire.endTransmission(true);

	return err_code;
}

uint8_t _ICM20948::getDeviceId(){
	// Who AM I 레지스터로부터 데이터를 읽어오는 함수
	uint8_t output = 0;

	Wire.beginTransmission(DEVICE_ID);
	Wire.write(WHO_AM_I);
	Wire.requestFrom(DEVICE_ID, 1);
	output = Wire.read();
	Wire.endTransmission(true);
	if(output != 234){
		return ROVERDYN_ERROR_NO_DATA;
	}
	return output;
}

uint8_t _ICM20948::getMagId(){
	// 지자기 센서의 WIA 레지스터로부터 데이터를 읽어오는 함수
	uint8_t output = 0;

	// Get Data
	Wire.beginTransmission(AK09916);
	Wire.write(WIA2);
	Wire.requestFrom(AK09916, 1);
	output = Wire.read();
	Wire.endTransmission(true);

	return output;
}

uint8_t _ICM20948::setCfgAcc(uint8_t ACCEL_DLPF_SEL, uint8_t ACCEL_FS_SEL, uint8_t ACCEL_AVG_SEL, bool Fchoice_b){
	// 가속도 센서의 측정 범위와 DLPF 적용 유무 설정 함수
	uint8_t err_code = 0;

	// Select Bank
	writeData(DEVICE_ID, REG_BANK_SEL, 0x20);

	// Set Accel Config 1
	uint8_t data = (ACCEL_DLPF_SEL << 3) | (ACCEL_FS_SEL << 1) | (Fchoice_b);
	writeData(DEVICE_ID, ACCEL_CONFIG, data);

	// Set Accel Config 2
	writeData(DEVICE_ID, ACCEL_CONFIG_2, ACCEL_FS_SEL);

	// Select Bank
	writeData(DEVICE_ID, REG_BANK_SEL, 0x00);

	return err_code;
}

uint8_t _ICM20948::setCfgGyro(uint8_t GYRO_DLPF_SEL, uint8_t GYRO_FS_SEL, uint8_t GYRO_AVG_SEL, bool Fchoice_b){
	// 자이로스코프의 측정 범위와 DLPF 적용 유무 설정 함수
	uint8_t err_code = 0;

	// Select Bank
	writeData(DEVICE_ID, REG_BANK_SEL, 0x20);

	// Set Gyro Config 1
	uint8_t data = (GYRO_DLPF_SEL << 3) | (GYRO_FS_SEL << 1) | (Fchoice_b);
	writeData(DEVICE_ID, GYRO_CONFIG_1, data);

	// Set Gyro Config 2
	writeData(DEVICE_ID, GYRO_CONFIG_2, GYRO_AVG_SEL);

	// Select Bank
	writeData(DEVICE_ID, REG_BANK_SEL, 0x00);

	return err_code;
}

uint8_t _ICM20948::setCfgTemp(uint8_t TEMP_DLPF_SET){
	// 온도 센서의 DLPF 설정
	uint8_t err_code = 0;

	// Select Bank
	writeData(DEVICE_ID, REG_BANK_SEL, 0x20);

	// Set DLPF
	writeData(DEVICE_ID, TEMP_CONFIG, TEMP_DLPF_SET);

	// Select Bank
	writeData(DEVICE_ID, REG_BANK_SEL, 0x00);

	return err_code;
}

uint8_t _ICM20948::setMagMode(uint8_t MODE){
	// 지자기 센서 설정 함수
	uint8_t err_code = 0;

	// Mode 설정
	writeData(AK09916, CNTL2, MODE);
	return err_code;
}

int16_t* _ICM20948::getMagASA(){
	// 지자기 센서 ASA 데이터 읽기 함수
	static int16_t output[3];

	return output;
}

int16_t* _ICM20948::getRawAcc(){
	// 가속도 센서 Raw 데이터 읽기 함수
	static int16_t output[3] = {0};

	// Select Bank
	writeData(DEVICE_ID, REG_BANK_SEL, 0x00);

	// Get Data
	Wire.beginTransmission(DEVICE_ID);
	Wire.write(ACCEL_XOUT_H);
	Wire.requestFrom(DEVICE_ID, 6);
	for(uint8_t i=0;i<3;i++){
		output[i] = Wire.read() << 8 | Wire.read();
	}
	Wire.endTransmission(true);
	return output;
}

int16_t* _ICM20948::getRawGyro(){
	// 자이로스코프 Raw 데이터 읽기 함수
	static int16_t output[3] = {0};

	// Select Bank
	writeData(DEVICE_ID, REG_BANK_SEL, 0x00);

	// Get Data
	Wire.beginTransmission(DEVICE_ID);
	Wire.write(GYRO_XOUT_H);
	Wire.requestFrom(DEVICE_ID, 6);
	for(uint8_t i=0;i<3;i++){
		output[i] = Wire.read() << 8 | Wire.read();
	}
	Wire.endTransmission(true);

	return output;
}

int16_t* _ICM20948::getRawMag(){
	// 지자기 센서 Raw 데이터 취득 함수
	static int16_t output[3] = {0};

	// Select Bank
	writeData(DEVICE_ID, REG_BANK_SEL, 0x00);

	// Get Data
	Wire.beginTransmission(AK09916);
	Wire.write(ST1);
	Wire.requestFrom(AK09916, 1);
	bool st1 = Wire.read() & 0x01;
	Wire.endTransmission(true);
	if(st1){
		// Read Mag Data
		Wire.beginTransmission(AK09916);
		Wire.write(HXL);
		Wire.requestFrom(AK09916, 6);
		for(uint8_t i=0;i<3;i++){
			output[i] = Wire.read();
			output[i] = (Wire.read() << 8) | output[i];
		}
		Wire.endTransmission(true);

		// Read ST2 register
		Wire.beginTransmission(AK09916);
		Wire.write(ST2);
		Wire.requestFrom(AK09916, 1);
		bool st2 = (Wire.read() >> 3) & 0x01;
		if(st2){
			return 0;
		}
		Wire.endTransmission(true);
	}
	return output;
}

float _ICM20948::getTemp(float TEMP_OFFSET){
	// 온도 데이터 수신 함수
	float output = 0;
	SEGGER_RTT_printf(0, "TEST\n");
	// Select Bank
	writeData(DEVICE_ID, REG_BANK_SEL, 0x00);

	// Get Data
	Wire.beginTransmission(DEVICE_ID);
	Wire.write(TEMP_OUT_H);
	Wire.requestFrom(DEVICE_ID, 2);
	output = Wire.read() << 8 | Wire.read();
	Wire.endTransmission(true);

	// 측정한 데이터를 Degree 단위로 변환
	output = ((output - TEMP_OFFSET)/TEMP_SENSITIVITY) + 21.0f;

	return output;
}

uint8_t _ICM20948::calibrateAccel(){
	// 가속도 센서 보정 함수
	uint8_t err_code = 0;
	uint16_t count = 0, itinary = 2000;
	int16_t avg[3] = {0}, accOffsetDefault[3] = {0};

	// Low 레지스터 1번 비트 받아옴
	// Select Bank
	writeData(DEVICE_ID, REG_BANK_SEL, 0x10);

	// Get Data
	for(uint8_t i=0;i<3;i++){
		Wire.beginTransmission(DEVICE_ID);
		Wire.write(XA_OFFS_H + i);
		Wire.requestFrom(DEVICE_ID, 2);
		accOffsetDefault[i] = Wire.read() << 8 | Wire.read();
		Wire.endTransmission(true);
	}

	// 초기값 평가
	int16_t *ACCEL;
	do{
		ACCEL = getRawAcc();
		count++;
		for(uint8_t i=0;i<3;i++){
			avg[i] = (float)((float)( (float)(count - 1)/(float)count ) * (float)avg[i - 1]) + ((float)((float)ACCEL[i] / count));
		}
	}while(count  <= itinary);

	while(1){

	}

	return err_code;
}
uint8_t _ICM20948::calibrateGyro(){
	// 자이로스코프 보정 함수
	uint8_t err_code = 0;
	return err_code;
}
uint8_t _ICM20948::calibrateMag(){
	// 지자기센서 보정 함수
	uint8_t err_code = 0;
	return err_code;
}

Please check it.

Thank you.

[awneil]

How are you making those graphs?

Have you got an I2C analyser to see what's actually happening on the bus?

[jswcomkr]

I've added CP2104 USB to UART bridge chipset for communication. I got the data from this IC and saved it as CSV format using 'Serial Plot' application on the Windows. After that, plot the data using MATLAB.

[awneil]

So you're sending data our of the nRF over a UART ?

Are you sure it's not the UART part that's going wrong ... ?

Again:

awneil said:

Have you got an I2C analyser to see what's actually happening on the bus

This looks like Arduino code.

Note that Nordic has nothing to do with the Arduino implementation.

[jswcomkr]

I was gather that data through the UART. If disable Bluetooth LE, there are no problems. Arduino codes was made by me for convinience. The first codes are Arduino-like(just like Wire library of Arduino). Purpose of this codes are gathering IMU data through Bluetooth LE UART services.

I guess that this problem caused from priority. is it right?

[jswcomkr]

But the other data not comes from TWI is fine such as RTC or Timer/Counter. Only TWI is not working.