# My gimbal program does not compile

my code:

``````// Get Yaw, Pitch and Roll values
mpu.dmpGetQuaternion(&q, fifoBuffer);
mpu.dmpGetGravity(&gravity, &q);
mpu.dmpGetYawPitchRoll(ypr, &q, &gravity);
// Yaw, Pitch, Roll values - Radians to degrees
ypr[0] = ypr[0] * 180 / M_PI;
ypr[1] = ypr[1] * 180 / M_PI;
ypr[2] = ypr[2] * 180 / M_PI;

// Skip 300 readings (self-calibration process)
if (j <= 300) {
correct = ypr[0]; // Yaw starts at random value, so we capture last value after 300 readings
j++;
}
else {
ypr[0] = ypr[0] - correct; // Set the Yaw to 0 deg - subtract  the last random Yaw value from the currrent value to make the Yaw 0 degrees
// Map the values of the MPU6050 sensor from -90 to 90 to values suatable for the servo control from 0 to 180
int servo0Value = map(ypr[0], -90, 90, 0, 180);
int servo1Value = map(ypr[1], -90, 90, 0, 180);
int servo2Value = map(ypr[2], -90, 90, 180, 0);

// Control the servos according to the MPU6050 orientation
servo0.write(servo0Value);
servo1.write(servo1Value);
servo2.write(servo2Value);
}
#endif

// Yaw, Pitch, Roll values - Radians to degrees
ypr[0] = ypr[0] * 180 / M_PI;
ypr[1] = ypr[1] * 180 / M_PI;
ypr[2] = ypr[2] * 180 / M_PI;

// Skip 300 readings (self-calibration process)
if (j <= 300) {
correct = ypr[0]; // Yaw starts at random value, so we capture last value after 300 readings
j++;
}

else {
ypr[0] = ypr[0] - correct; // Set the Yaw to 0 deg - subtract  the last random Yaw value from the currrent value to make the Yaw 0 degrees
// Map the values of the MPU6050 sensor from -90 to 90 to values suatable for the servo control from 0 to 180
int servo0Value = map(ypr[0], -90, 90, 0, 180);
int servo1Value = map(ypr[1], -90, 90, 0, 180);
int servo2Value = map(ypr[2], -90, 90, 180, 0);

// Control the servos according to the MPU6050 orientation
servo0.write(servo0Value);
servo1.write(servo1Value);
servo2.write(servo2Value);
}
``````

it says ypr does not name a type

``````/*
Arduino and MPU6050 Accelerometer and Gyroscope Sensor Tutorial
by Dejan, https://howtomechatronics.com
*/
#include <Wire.h>
const int MPU = 0x68; // MPU6050 I2C address
float AccX, AccY, AccZ;
float GyroX, GyroY, GyroZ;
float accAngleX, accAngleY, gyroAngleX, gyroAngleY, gyroAngleZ;
float roll, pitch, yaw;
float AccErrorX, AccErrorY, GyroErrorX, GyroErrorY, GyroErrorZ;
float elapsedTime, currentTime, previousTime;
int c = 0;
void setup() {
Serial.begin(19200);
Wire.begin();                      // Initialize comunication
Wire.beginTransmission(MPU);       // Start communication with MPU6050 // MPU=0x68
Wire.write(0x6B);                  // Talk to the register 6B
Wire.write(0x00);                  // Make reset - place a 0 into the 6B register
Wire.endTransmission(true);        //end the transmission
/*
// Configure Accelerometer Sensitivity - Full Scale Range (default +/- 2g)
Wire.beginTransmission(MPU);
Wire.write(0x1C);                  //Talk to the ACCEL_CONFIG register (1C hex)
Wire.write(0x10);                  //Set the register bits as 00010000 (+/- 8g full scale range)
Wire.endTransmission(true);
// Configure Gyro Sensitivity - Full Scale Range (default +/- 250deg/s)
Wire.beginTransmission(MPU);
Wire.write(0x1B);                   // Talk to the GYRO_CONFIG register (1B hex)
Wire.write(0x10);                   // Set the register bits as 00010000 (1000deg/s full scale)
Wire.endTransmission(true);
delay(20);
*/
// Call this function if you need to get the IMU error values for your module
calculate_IMU_error();
delay(20);
}

void loop() {
// === Read acceleromter data === //
Wire.beginTransmission(MPU);
Wire.endTransmission(false);
Wire.requestFrom(MPU, 6, true); // Read 6 registers total, each axis value is stored in 2 registers
//For a range of +-2g, we need to divide the raw values by 16384, according to the datasheet
AccX = (Wire.read() << 8 | Wire.read()) / 16384.0; // X-axis value
AccY = (Wire.read() << 8 | Wire.read()) / 16384.0; // Y-axis value
AccZ = (Wire.read() << 8 | Wire.read()) / 16384.0; // Z-axis value
// Calculating Roll and Pitch from the accelerometer data
accAngleX = (atan(AccY / sqrt(pow(AccX, 2) + pow(AccZ, 2))) * 180 / PI) - 0.58; // AccErrorX ~(0.58) See the calculate_IMU_error()custom function for more details
accAngleY = (atan(-1 * AccX / sqrt(pow(AccY, 2) + pow(AccZ, 2))) * 180 / PI) + 1.58; // AccErrorY ~(-1.58)
// === Read gyroscope data === //
previousTime = currentTime;        // Previous time is stored before the actual time read
currentTime = millis();            // Current time actual time read
elapsedTime = (currentTime - previousTime) / 1000; // Divide by 1000 to get seconds
Wire.beginTransmission(MPU);
Wire.write(0x43); // Gyro data first register address 0x43
Wire.endTransmission(false);
Wire.requestFrom(MPU, 6, true); // Read 4 registers total, each axis value is stored in 2 registers
GyroX = (Wire.read() << 8 | Wire.read()) / 131.0; // For a 250deg/s range we have to divide first the raw value by 131.0, according to the datasheet
// Correct the outputs with the calculated error values
GyroX = GyroX + 0.56; // GyroErrorX ~(-0.56)
GyroY = GyroY - 2; // GyroErrorY ~(2)
GyroZ = GyroZ + 0.79; // GyroErrorZ ~ (-0.8)
// Currently the raw values are in degrees per seconds, deg/s, so we need to multiply by sendonds (s) to get the angle in degrees
gyroAngleX = gyroAngleX + GyroX * elapsedTime; // deg/s * s = deg
gyroAngleY = gyroAngleY + GyroY * elapsedTime;
yaw =  yaw + GyroZ * elapsedTime;
// Complementary filter - combine acceleromter and gyro angle values
roll = 0.96 * gyroAngleX + 0.04 * accAngleX;
pitch = 0.96 * gyroAngleY + 0.04 * accAngleY;

// Print the values on the serial monitor
Serial.print(roll);
Serial.print("/");
Serial.print(pitch);
Serial.print("/");
Serial.println(yaw);
}

void calculate_IMU_error() {
// We can call this funtion in the setup section to calculate the accelerometer and gyro data error. From here we will get the error values used in the above equations printed on the Serial Monitor.
// Note that we should place the IMU flat in order to get the proper values, so that we then can the correct values
// Read accelerometer values 200 times
while (c < 200) {
Wire.beginTransmission(MPU);
Wire.write(0x3B);
Wire.endTransmission(false);
Wire.requestFrom(MPU, 6, true);
AccErrorX = AccErrorX + ((atan((AccY) / sqrt(pow((AccX), 2) + pow((AccZ), 2))) * 180 / PI));
AccErrorY = AccErrorY + ((atan(-1 * (AccX) / sqrt(pow((AccY), 2) + pow((AccZ), 2))) * 180 / PI));
c++;
}
//Divide the sum by 200 to get the error value
AccErrorX = AccErrorX / 200;
AccErrorY = AccErrorY / 200;
c = 0;
// Read gyro values 200 times
while (c < 200) {
Wire.beginTransmission(MPU);
Wire.write(0x43);
Wire.endTransmission(false);
Wire.requestFrom(MPU, 6, true);
GyroErrorX = GyroErrorX + (GyroX / 131.0);
GyroErrorY = GyroErrorY + (GyroY / 131.0);
GyroErrorZ = GyroErrorZ + (GyroZ / 131.0);
c++;
}
//Divide the sum by 200 to get the error value
GyroErrorX = GyroErrorX / 200;
GyroErrorY = GyroErrorY / 200;
GyroErrorZ = GyroErrorZ / 200;
// Print the error values on the Serial Monitor
Serial.print("AccErrorX: ");
Serial.println(AccErrorX);
Serial.print("AccErrorY: ");
Serial.println(AccErrorY);
Serial.print("GyroErrorX: ");
Serial.println(GyroErrorX);
Serial.print("GyroErrorY: ");
Serial.println(GyroErrorY);
Serial.print("GyroErrorZ: ");
Serial.println(GyroErrorZ);
}

Wire.beginTransmission(MPU);
Wire.write(0x1C);                  //Talk to the ACCEL_CONFIG register (1C hex)
Wire.write(0x10);                  //Set the register bits as 00010000 (+/- 8g full scale range)
Wire.endTransmission(true);
// Configure Gyro Sensitivity - Full Scale Range (default +/- 250deg/s)
Wire.beginTransmission(MPU);
Wire.write(0x1B);                   // Talk to the GYRO_CONFIG register (1B hex)
Wire.write(0x10);                   // Set the register bits as 00010000 (1000deg/s full scale)
Wire.endTransmission(true);
*/

Wire.beginTransmission(MPU);
Wire.endTransmission(false);
Wire.requestFrom(MPU, 6, true); // Read 6 registers total, each axis value is stored in 2 registers
//For a range of +-2g, we need to divide the raw values by 16384, according to the datasheet
AccX = (Wire.read() << 8 | Wire.read()) / 16384.0; // X-axis value
AccY = (Wire.read() << 8 | Wire.read()) / 16384.0; // Y-axis value
AccZ = (Wire.read() << 8 | Wire.read()) / 16384.0; // Z-axis value

accAngleX = (atan(AccY / sqrt(pow(AccX, 2) + pow(AccZ, 2))) * 180 / PI) - 0.58; // AccErrorX ~(0.58) See the calculate_IMU_error()custom function for more details
accAngleY = (atan(-1 * AccX / sqrt(pow(AccY, 2) + pow(AccZ, 2))) * 180 / PI) + 1.58; // AccErrorY ~(-1.58)

previousTime = currentTime;        // Previous time is stored before the actual time read
currentTime = millis();            // Current time actual time read
elapsedTime = (currentTime - previousTime) / 1000; // Divide by 1000 to get seconds
Wire.beginTransmission(MPU);
Wire.write(0x43); // Gyro data first register address 0x43
Wire.endTransmission(false);
Wire.requestFrom(MPU, 6, true); // Read 4 registers total, each axis value is stored in 2 registers
GyroX = (Wire.read() << 8 | Wire.read()) / 131.0; // For a 250deg/s range we have to divide first the raw value by 131.0, according to the datasheet
GyroX = GyroX + 0.56; // GyroErrorX ~(-0.56)
GyroY = GyroY - 2; // GyroErrorY ~(2)
GyroZ = GyroZ + 0.79; // GyroErrorZ ~ (-0.8)
// Currently the raw values are in degrees per seconds, deg/s, so we need to multiply by sendonds (s) to get the angle in degrees
gyroAngleX = gyroAngleX + GyroX * elapsedTime; // deg/s * s = deg
gyroAngleY = gyroAngleY + GyroY * elapsedTime;
yaw =  yaw + GyroZ * elapsedTime;

roll = 0.96 * gyroAngleX + 0.04 * accAngleX;
pitch = 0.96 * gyroAngleY + 0.04 * accAngleY;

void calculate_IMU_error() {
// We can call this funtion in the setup section to calculate the accelerometer and gyro data error. From here we will get the error values used in the above equations printed on the Serial Monitor.
// Note that we should place the IMU flat in order to get the proper values, so that we then can the correct values
// Read accelerometer values 200 times
while (c < 200) {
Wire.beginTransmission(MPU);
Wire.write(0x3B);
Wire.endTransmission(false);
Wire.requestFrom(MPU, 6, true);
AccErrorX = AccErrorX + ((atan((AccY) / sqrt(pow((AccX), 2) + pow((AccZ), 2))) * 180 / PI));
AccErrorY = AccErrorY + ((atan(-1 * (AccX) / sqrt(pow((AccY), 2) + pow((AccZ), 2))) * 180 / PI));
c++;
}
//Divide the sum by 200 to get the error value
AccErrorX = AccErrorX / 200;
AccErrorY = AccErrorY / 200;
c = 0;
// Read gyro values 200 times
while (c < 200) {
Wire.beginTransmission(MPU);
Wire.write(0x43);
Wire.endTransmission(false);
Wire.requestFrom(MPU, 6, true);
GyroErrorX = GyroErrorX + (GyroX / 131.0);
GyroErrorY = GyroErrorY + (GyroY / 131.0);
GyroErrorZ = GyroErrorZ + (GyroZ / 131.0);
c++;
}
//Divide the sum by 200 to get the error value
GyroErrorX = GyroErrorX / 200;
GyroErrorY = GyroErrorY / 200;
GyroErrorZ = GyroErrorZ / 200;
// Print the error values on the Serial Monitor
Serial.print("AccErrorX: ");
Serial.println(AccErrorX);
Serial.print("AccErrorY: ");
Serial.println(AccErrorY);
Serial.print("GyroErrorX: ");
Serial.println(GyroErrorX);
Serial.print("GyroErrorY: ");
Serial.println(GyroErrorY);
Serial.print("GyroErrorZ: ");
Serial.println(GyroErrorZ);
}
``````

We simply print the values on the serial monitor and once we know them, we can implement them in the code as shown earlier, for both the roll and pitch calculation, as well as for the 3 gyroscope outputs.

MPU6050 Pitch Roll and Yaw outputs

Finally, using the Serial.print function we can print the Roll, Pitch and Yaw values on the serial monitor and see whether the sensor works properly.

``````#ifdef OUTPUT_READABLE_YAWPITCHROLL
mpu.dmpGetQuaternion(&q, fifoBuffer);
mpu.dmpGetGravity(&gravity, &q);
mpu.dmpGetYawPitchRoll(ypr, &q, &gravity);

ypr[0] = ypr[0] * 180 / M_PI;
ypr[1] = ypr[1] * 180 / M_PI;
ypr[2] = ypr[2] * 180 / M_PI;

if (j <= 300) {
correct = ypr[0];
j++;
}
else {
ypr[0] = ypr[0] - correct;
int servo0Value = map(ypr[0], -90, 90, 0, 180);
int servo1Value = map(ypr[1], -90, 90, 0, 180);
int servo2Value = map(ypr[2], -90, 90, 180, 0);

servo0.write(servo0Value);
servo1.write(servo1Value);
servo2.write(servo2Value);
}
#endif

ypr[0] = ypr[0] * 180 / M_PI;
ypr[1] = ypr[1] * 180 / M_PI;
ypr[2] = ypr[2] * 180 / M_PI;

if (j <= 300) {
correct = ypr[0];
j++;
}
else {
ypr[0] = ypr[0] - correct;
int servo0Value = map(ypr[0], -90, 90, 0, 180);
int servo1Value = map(ypr[1], -90, 90, 0, 180);
int servo2Value = map(ypr[2], -90, 90, 180, 0);

servo0.write(servo0Value);
servo1.write(servo1Value);
servo2.write(servo2Value);
}
``````
• Please show us your full code. Did you define `ypr` beforehand? Jan 5 '20 at 17:06
• as well as any error messages from the debug console Jan 6 '20 at 0:15

I know this is more of a comment but I can't do that yet.

This is for the code with wire.h at the top of the code.

I loaded your code into my arduino IDE and my line numbers reference those

1. You have lines 22-32 commented out.

2. The // at the end of line 40 may cause you problems.

3. If lines 41-43 the same that you have in void setup () the same then you have the program doing something over and over again, that has already been set up.

4. line 145 you have a lone */ that the compiler should have found.

5. Lines 136 to 178 are not inside {} are not being run. They also look very similar to what is inside your void loop()

6. Line 180 has the same `void calculate_IMU_error() {` as on line 80, which one is being ran?