Witmotion Sensor IMU| WT901C232 | Arduino UNO R3

szahra · January 20, 2025, 7:06pm

So I have this code from the witmotion sdk. I have the Witmotion WT901C232 Sensor.

#include <REG.h>
#include <wit_c_sdk.h>

/*
Test on UNO R3. use WT901CTTL sensor

WT901232   UNO R3
    VCC <--->  5V/3.3V
    TX  <--->  1(TX1)
    RX  <--->  O(RX1)
    GND <--->  GND
*/

#define ACC_UPDATE		0x01
#define GYRO_UPDATE		0x02
#define ANGLE_UPDATE	0x04
#define MAG_UPDATE		0x08
#define READ_UPDATE		0x80
static volatile char s_cDataUpdate = 0, s_cCmd = 0xff; 

static void CmdProcess(void);
static void AutoScanSensor(void);
static void SensorUartSend(uint8_t *p_data, uint32_t uiSize);
static void SensorDataUpdata(uint32_t uiReg, uint32_t uiRegNum);
static void Delayms(uint16_t ucMs);
const uint32_t c_uiBaud[8] = {0,4800, 9600, 19200, 38400, 57600, 115200, 230400};

void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);
	WitInit(WIT_PROTOCOL_NORMAL, 0x50);
	WitSerialWriteRegister(SensorUartSend);
	WitRegisterCallBack(SensorDataUpdata);
  WitDelayMsRegister(Delayms);
	Serial.print("\r\n********************** wit-motion normal example  ************************\r\n");
	AutoScanSensor();
}
int i;
float fAcc[3], fGyro[3], fAngle[3];
void loop() {
    while (Serial1.available())
    {
      WitSerialDataIn(Serial1.read());
    }
    while (Serial.available()) 
    {
      CopeCmdData(Serial.read());
    }
		CmdProcess();
		if(s_cDataUpdate)
		{
			for(i = 0; i < 3; i++)
			{
				fAcc[i] = sReg[AX+i] / 32768.0f * 16.0f;
				fGyro[i] = sReg[GX+i] / 32768.0f * 2000.0f;
				fAngle[i] = sReg[Roll+i] / 32768.0f * 180.0f;
			}
			if(s_cDataUpdate & ACC_UPDATE)
			{
				Serial.print("acc:");
				Serial.print(fAcc[0], 3);
				Serial.print(" ");
				Serial.print(fAcc[1], 3);
				Serial.print(" ");
				Serial.print(fAcc[2], 3);
				Serial.print("\r\n");
				s_cDataUpdate &= ~ACC_UPDATE;
			}
			if(s_cDataUpdate & GYRO_UPDATE)
			{
				Serial.print("gyro:");
				Serial.print(fGyro[0], 1);
				Serial.print(" ");
				Serial.print(fGyro[1], 1);
				Serial.print(" ");
				Serial.print(fGyro[2], 1);
				Serial.print("\r\n");
				s_cDataUpdate &= ~GYRO_UPDATE;
			}
			if(s_cDataUpdate & ANGLE_UPDATE)
			{
				Serial.print("angle:");
				Serial.print(fAngle[0], 3);
				Serial.print(" ");
				Serial.print(fAngle[1], 3);
				Serial.print(" ");
				Serial.print(fAngle[2], 3);
				Serial.print("\r\n");
				s_cDataUpdate &= ~ANGLE_UPDATE;
			}
			if(s_cDataUpdate & MAG_UPDATE)
			{
				Serial.print("mag:");
				Serial.print(sReg[HX]);
				Serial.print(" ");
				Serial.print(sReg[HY]);
				Serial.print(" ");
				Serial.print(sReg[HZ]);
				Serial.print("\r\n");
				s_cDataUpdate &= ~MAG_UPDATE;
			}
      s_cDataUpdate = 0;
		}
}


void CopeCmdData(unsigned char ucData)
{
	static unsigned char s_ucData[50], s_ucRxCnt = 0;
	
	s_ucData[s_ucRxCnt++] = ucData;
	if(s_ucRxCnt<3)return;										//Less than three data returned
	if(s_ucRxCnt >= 50) s_ucRxCnt = 0;
	if(s_ucRxCnt >= 3)
	{
		if((s_ucData[1] == '\r') && (s_ucData[2] == '\n'))
		{
			s_cCmd = s_ucData[0];
			memset(s_ucData,0,50);
			s_ucRxCnt = 0;
		}
		else 
		{
			s_ucData[0] = s_ucData[1];
			s_ucData[1] = s_ucData[2];
			s_ucRxCnt = 2;
			
		}
	}
}
static void ShowHelp(void)
{
	Serial.print("\r\n************************	 WIT_SDK_DEMO	************************");
	Serial.print("\r\n************************          HELP           ************************\r\n");
	Serial.print("UART SEND:a\\r\\n   Acceleration calibration.\r\n");
	Serial.print("UART SEND:m\\r\\n   Magnetic field calibration,After calibration send:   e\\r\\n   to indicate the end\r\n");
	Serial.print("UART SEND:U\\r\\n   Bandwidth increase.\r\n");
	Serial.print("UART SEND:u\\r\\n   Bandwidth reduction.\r\n");
	Serial.print("UART SEND:B\\r\\n   Baud rate increased to 115200.\r\n");
	Serial.print("UART SEND:b\\r\\n   Baud rate reduction to 9600.\r\n");
	Serial.print("UART SEND:R\\r\\n   The return rate increases to 10Hz.\r\n");
  Serial.print("UART SEND:r\\r\\n   The return rate reduction to 1Hz.\r\n");
  Serial.print("UART SEND:C\\r\\n   Basic return content: acceleration, angular velocity, angle, magnetic field.\r\n");
  Serial.print("UART SEND:c\\r\\n   Return content: acceleration.\r\n");
  Serial.print("UART SEND:h\\r\\n   help.\r\n");
	Serial.print("******************************************************************************\r\n");
}

static void CmdProcess(void)
{
	switch(s_cCmd)
	{
		case 'a':	if(WitStartAccCali() != WIT_HAL_OK) Serial.print("\r\nSet AccCali Error\r\n");
			break;
		case 'm':	if(WitStartMagCali() != WIT_HAL_OK) Serial.print("\r\nSet MagCali Error\r\n");
			break;
		case 'e':	if(WitStopMagCali() != WIT_HAL_OK) Serial.print("\r\nSet MagCali Error\r\n");
			break;
		case 'u':	if(WitSetBandwidth(BANDWIDTH_5HZ) != WIT_HAL_OK) Serial.print("\r\nSet Bandwidth Error\r\n");
			break;
		case 'U':	if(WitSetBandwidth(BANDWIDTH_256HZ) != WIT_HAL_OK) Serial.print("\r\nSet Bandwidth Error\r\n");
			break;
		case 'B':	if(WitSetUartBaud(WIT_BAUD_115200) != WIT_HAL_OK) Serial.print("\r\nSet Baud Error\r\n");
              else 
              {
                Serial1.begin(c_uiBaud[WIT_BAUD_115200]);
                Serial.print(" 115200 Baud rate modified successfully\r\n");
              }
			break;
		case 'b':	if(WitSetUartBaud(WIT_BAUD_9600) != WIT_HAL_OK) Serial.print("\r\nSet Baud Error\r\n");
              else 
              {
                Serial1.begin(c_uiBaud[WIT_BAUD_9600]); 
                Serial.print(" 9600 Baud rate modified successfully\r\n");
              }
			break;
		case 'r': if(WitSetOutputRate(RRATE_1HZ) != WIT_HAL_OK)  Serial.print("\r\nSet Baud Error\r\n");
			        else Serial.print("\r\nSet Baud Success\r\n");
			break;
		case 'R':	if(WitSetOutputRate(RRATE_10HZ) != WIT_HAL_OK) Serial.print("\r\nSet Baud Error\r\n");
              else Serial.print("\r\nSet Baud Success\r\n");
			break;
    case 'C': if(WitSetContent(RSW_ACC|RSW_GYRO|RSW_ANGLE|RSW_MAG) != WIT_HAL_OK) Serial.print("\r\nSet RSW Error\r\n");
      break;
    case 'c': if(WitSetContent(RSW_ACC) != WIT_HAL_OK) Serial.print("\r\nSet RSW Error\r\n");
      break;
		case 'h':	ShowHelp();
			break;
		default :break;
	}
	s_cCmd = 0xff;
}
static void SensorUartSend(uint8_t *p_data, uint32_t uiSize)
{
  Serial1.write(p_data, uiSize);
  Serial1.flush();
}
static void Delayms(uint16_t ucMs)
{
  delay(ucMs);
}
static void SensorDataUpdata(uint32_t uiReg, uint32_t uiRegNum)
{
	int i;
    for(i = 0; i < uiRegNum; i++)
    {
        switch(uiReg)
        {
            case AZ:
				s_cDataUpdate |= ACC_UPDATE;
            break;
            case GZ:
				s_cDataUpdate |= GYRO_UPDATE;
            break;
            case HZ:
				s_cDataUpdate |= MAG_UPDATE;
            break;
            case Yaw:
				s_cDataUpdate |= ANGLE_UPDATE;
            break;
            default:
				s_cDataUpdate |= READ_UPDATE;
			break;
        }
		uiReg++;
    }
}

static void AutoScanSensor(void)
{
	int i, iRetry;
	
	for(i = 0; i < sizeof(c_uiBaud)/sizeof(c_uiBaud[0]); i++)
	{
		Serial1.begin(c_uiBaud[i]);
    Serial1.flush();
		iRetry = 2;
		s_cDataUpdate = 0;
		do
		{
			WitReadReg(AX, 3);
			delay(200);
      while (Serial1.available())
      {
        WitSerialDataIn(Serial1.read());
      }
			if(s_cDataUpdate != 0)
			{
				Serial.print(c_uiBaud[i]);
				Serial.print(" baud find sensor\r\n\r\n");
				ShowHelp();
				return ;
			}
			iRetry--;
		}while(iRetry);		
	}
	Serial.print("can not find sensor\r\n");
	Serial.print("please check your connection\r\n");
}

I simplified it like this due to memory issues because all I want is just readings.

#include <REG.h>
#include <wit_c_sdk.h>

#define ACC_UPDATE   0x01
#define GYRO_UPDATE  0x02
#define ANGLE_UPDATE 0x04

static volatile char s_cDataUpdate = 0;

void SensorUartSend(uint8_t *p_data, uint32_t uiSize);
void SensorDataUpdata(uint32_t uiReg, uint32_t uiRegNum);
void Delayms(uint16_t ucMs);

const uint32_t c_uiBaud[8] = {0, 4800, 9600, 19200, 38400, 57600, 115200, 230400};

void setup() {
    Serial.begin(9600);
    WitInit(WIT_PROTOCOL_NORMAL, 0x50);
    WitSerialWriteRegister(SensorUartSend);
    WitRegisterCallBack(SensorDataUpdata);
    WitDelayMsRegister(Delayms);
}

void loop() {
    while (Serial.available()) {
        WitSerialDataIn(Serial.read());
    }

    if (s_cDataUpdate) {
        float fAcc[3], fGyro[3], fAngle[3];
        for (int i = 0; i < 3; i++) {
            fAcc[i] = sReg[AX + i] / 32768.0f * 16.0f;
            fGyro[i] = sReg[GX + i] / 32768.0f * 2000.0f;
            fAngle[i] = sReg[Roll + i] / 32768.0f * 180.0f;
        }

        if (s_cDataUpdate & ACC_UPDATE) {
            Serial.print("acc:");
            Serial.print(fAcc[0], 3); Serial.print(" ");
            Serial.print(fAcc[1], 3); Serial.print(" ");
            Serial.println(fAcc[2], 3);
            s_cDataUpdate &= ~ACC_UPDATE;
        }

        if (s_cDataUpdate & GYRO_UPDATE) {
            Serial.print("gyro:");
            Serial.print(fGyro[0], 1); Serial.print(" ");
            Serial.print(fGyro[1], 1); Serial.print(" ");
            Serial.println(fGyro[2], 1);
            s_cDataUpdate &= ~GYRO_UPDATE;
        }

        if (s_cDataUpdate & ANGLE_UPDATE) {
            Serial.print("angle:");
            Serial.print(fAngle[0], 3); Serial.print(" ");
            Serial.print(fAngle[1], 3); Serial.print(" ");
            Serial.println(fAngle[2], 3);
            s_cDataUpdate &= ~ANGLE_UPDATE;
        }
    }
}

void SensorUartSend(uint8_t *p_data, uint32_t uiSize) {
    Serial.write(p_data, uiSize);
    Serial.flush();
}

void Delayms(uint16_t ucMs) {
    delay(ucMs);
}

void SensorDataUpdata(uint32_t uiReg, uint32_t uiRegNum) {
    for (uint32_t i = 0; i < uiRegNum; i++) {
        switch (uiReg) {
            case AZ:
                s_cDataUpdate |= ACC_UPDATE;
                break;
            case GZ:
                s_cDataUpdate |= GYRO_UPDATE;
                break;
            case Yaw:
                s_cDataUpdate |= ANGLE_UPDATE;
                break;
            default:
                break;
        }
        uiReg++;
    }
}

Both codes , I get encrypted characters and I changed baud rates aswell and I cannot get any readings at all.

jremington · January 20, 2025, 7:23pm

Suspect incorrect serial baud rates. Study the sensor data sheet, and make sure the Arduino serial monitor is set to the same baud rate as used for Serial.print in your code.

Post the system wiring diagram associated with each program you posted. Why do they use different serial ports?

szahra · January 20, 2025, 9:45pm

Hello I have set the correct baud rates.

I have VCC to 5V
GND to GND

TX to 0 Pin
RX to 1 Pin

jremington · January 20, 2025, 9:58pm

You can't expect this to work, because on the Uno R3 the hardware serial port is dedicated to program upload and debugging, with pins 0 and 1 internally connected to the 16U2 USB-serial converter chip.

To interface with UART serial devices using the Uno R3, most people use SoftwareSerial on different pins.

system · July 19, 2025, 9:58pm

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Witmotion Sensor IMU| WT901C232 | Arduino UNO R3

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