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example.c
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example.c
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/*
///////////////////////////////////////////////////////////////////////////////////////
/*Terms of use
///////////////////////////////////////////////////////////////////////////////////////
//THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
//IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
//FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
//AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
//LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
//OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
//THE SOFTWARE.
///////////////////////////////////////////////////////////////////////////////////////
//Support
///////////////////////////////////////////////////////////////////////////////////////
Website: http://www.brokking.net/imu.html
Youtube: https://youtu.be/4BoIE8YQwM8
Version: 1.0 (May 5, 2016)
///////////////////////////////////////////////////////////////////////////////////////
//Connections
///////////////////////////////////////////////////////////////////////////////////////
Power (5V) is provided to the Arduino pro mini by the FTDI programmer
Gyro - Arduino pro mini
VCC - 5V
GND - GND
SDA - A4
SCL - A5
LCD - Arduino pro mini
VCC - 5V
GND - GND
SDA - A4
SCL - A5
*//////////////////////////////////////////////////////////////////////////////////////
//Include LCD and I2C library
#include <LiquidCrystal_I2C.h>
#include <Wire.h>
//Declaring some global variables
int gyro_x, gyro_y, gyro_z;
long acc_x, acc_y, acc_z, acc_total_vector;
boolean set_gyro_angles;
int temperature;
long loop_timer;
int lcd_loop_counter;
float angle_pitch, angle_roll;
int angle_pitch_buffer, angle_roll_buffer;
float angle_roll_acc, angle_pitch_acc;
float angle_pitch_output, angle_roll_output;
//Initialize the LCD library
LiquidCrystal_I2C lcd(0x27,16,2);
void setup() {
Wire.begin(); //Start I2C as master
//Serial.begin(57600); //Use only for debugging
pinMode(13, OUTPUT); //Set output 13 (LED) as output
setup_mpu_6050_registers(); //Setup the registers of the MPU-6050 (500dfs / +/-8g) and start the gyro
digitalWrite(13, HIGH); //Set digital output 13 high to indicate startup
lcd.begin(); //Initialize the LCD
lcd.backlight(); //Activate backlight
lcd.clear(); //Clear the LCD
lcd.setCursor(0,0); //Set the LCD cursor to position to position 0,0
lcd.print(" MPU-6050 IMU"); //Print text to screen
lcd.setCursor(0,1); //Set the LCD cursor to position to position 0,1
lcd.print(" V1.0"); //Print text to screen
delay(1500); //Delay 1.5 second to display the text
lcd.clear(); //Clear the LCD
lcd.setCursor(0,0); //Set the LCD cursor to position to position 0,0
lcd.print("Calibrating gyro"); //Print text to screen
lcd.setCursor(0,1); //Set the LCD cursor to position to position 0,1
for (int cal_int = 0; cal_int < 2000 ; cal_int ++){ //Run this code 2000 times
if(cal_int % 125 == 0)lcd.print("."); //Print a dot on the LCD every 125 readings
read_mpu_6050_data(); //Read the raw acc and gyro data from the MPU-6050
gyro_x_cal += gyro_x; //Add the gyro x-axis offset to the gyro_x_cal variable
gyro_y_cal += gyro_y; //Add the gyro y-axis offset to the gyro_y_cal variable
gyro_z_cal += gyro_z; //Add the gyro z-axis offset to the gyro_z_cal variable
delay(3); //Delay 3us to simulate the 250Hz program loop
}
gyro_x_cal /= 2000; //Divide the gyro_x_cal variable by 2000 to get the avarage offset
gyro_y_cal /= 2000; //Divide the gyro_y_cal variable by 2000 to get the avarage offset
gyro_z_cal /= 2000; //Divide the gyro_z_cal variable by 2000 to get the avarage offset
lcd.clear(); //Clear the LCD
lcd.setCursor(0,0); //Set the LCD cursor to position to position 0,0
lcd.print("Pitch:"); //Print text to screen
lcd.setCursor(0,1); //Set the LCD cursor to position to position 0,1
lcd.print("Roll :"); //Print text to screen
digitalWrite(13, LOW); //All done, turn the LED off
loop_timer = micros(); //Reset the loop timer
}
void loop(){
read_mpu_6050_data(); //Read the raw acc and gyro data from the MPU-6050
gyro_x -= gyro_x_cal; //Subtract the offset calibration value from the raw gyro_x value
gyro_y -= gyro_y_cal; //Subtract the offset calibration value from the raw gyro_y value
gyro_z -= gyro_z_cal; //Subtract the offset calibration value from the raw gyro_z value
//Gyro angle calculations
//0.0000611 = 1 / (250Hz / 65.5)
angle_pitch += gyro_x * 0.0000611; //Calculate the traveled pitch angle and add this to the angle_pitch variable
angle_roll += gyro_y * 0.0000611; //Calculate the traveled roll angle and add this to the angle_roll variable
//0.000001066 = 0.0000611 * (3.142(PI) / 180degr) The Arduino sin function is in radians
angle_pitch += angle_roll * sin(gyro_z * 0.000001066); //If the IMU has yawed transfer the roll angle to the pitch angel
angle_roll -= angle_pitch * sin(gyro_z * 0.000001066); //If the IMU has yawed transfer the pitch angle to the roll angel
//Accelerometer angle calculations
acc_total_vector = sqrt((acc_x*acc_x)+(acc_y*acc_y)+(acc_z*acc_z)); //Calculate the total accelerometer vector
//57.296 = 1 / (3.142 / 180) The Arduino asin function is in radians
angle_pitch_acc = asin((float)acc_y/acc_total_vector)* 57.296; //Calculate the pitch angle
angle_roll_acc = asin((float)acc_x/acc_total_vector)* -57.296; //Calculate the roll angle
//Place the MPU-6050 spirit level and note the values in the following two lines for calibration
angle_pitch_acc -= 0.0; //Accelerometer calibration value for pitch
angle_roll_acc -= 0.0; //Accelerometer calibration value for roll
if(set_gyro_angles){ //If the IMU is already started
angle_pitch = angle_pitch * 0.9996 + angle_pitch_acc * 0.0004; //Correct the drift of the gyro pitch angle with the accelerometer pitch angle
angle_roll = angle_roll * 0.9996 + angle_roll_acc * 0.0004; //Correct the drift of the gyro roll angle with the accelerometer roll angle
}
else{ //At first start
angle_pitch = angle_pitch_acc; //Set the gyro pitch angle equal to the accelerometer pitch angle
angle_roll = angle_roll_acc; //Set the gyro roll angle equal to the accelerometer roll angle
set_gyro_angles = true; //Set the IMU started flag
}
//To dampen the pitch and roll angles a complementary filter is used
angle_pitch_output = angle_pitch_output * 0.9 + angle_pitch * 0.1; //Take 90% of the output pitch value and add 10% of the raw pitch value
angle_roll_output = angle_roll_output * 0.9 + angle_roll * 0.1; //Take 90% of the output roll value and add 10% of the raw roll value
write_LCD(); //Write the roll and pitch values to the LCD display
while(micros() - loop_timer < 4000); //Wait until the loop_timer reaches 4000us (250Hz) before starting the next loop
loop_timer = micros(); //Reset the loop timer
}
void read_mpu_6050_data(){ //Subroutine for reading the raw gyro and accelerometer data
Wire.beginTransmission(0x68); //Start communicating with the MPU-6050
Wire.write(0x3B); //Send the requested starting register
Wire.endTransmission(); //End the transmission
Wire.requestFrom(0x68,14); //Request 14 bytes from the MPU-6050
while(Wire.available() < 14); //Wait until all the bytes are received
acc_x = Wire.read()<<8|Wire.read(); //Add the low and high byte to the acc_x variable
acc_y = Wire.read()<<8|Wire.read(); //Add the low and high byte to the acc_y variable
acc_z = Wire.read()<<8|Wire.read(); //Add the low and high byte to the acc_z variable
temperature = Wire.read()<<8|Wire.read(); //Add the low and high byte to the temperature variable
gyro_x = Wire.read()<<8|Wire.read(); //Add the low and high byte to the gyro_x variable
gyro_y = Wire.read()<<8|Wire.read(); //Add the low and high byte to the gyro_y variable
gyro_z = Wire.read()<<8|Wire.read(); //Add the low and high byte to the gyro_z variable
}
void write_LCD(){ //Subroutine for writing the LCD
//To get a 250Hz program loop (4us) it's only possible to write one character per loop
//Writing multiple characters is taking to much time
if(lcd_loop_counter == 14)lcd_loop_counter = 0; //Reset the counter after 14 characters
lcd_loop_counter ++; //Increase the counter
if(lcd_loop_counter == 1){
angle_pitch_buffer = angle_pitch_output * 10; //Buffer the pitch angle because it will change
lcd.setCursor(6,0); //Set the LCD cursor to position to position 0,0
}
if(lcd_loop_counter == 2){
if(angle_pitch_buffer < 0)lcd.print("-"); //Print - if value is negative
else lcd.print("+"); //Print + if value is negative
}
if(lcd_loop_counter == 3)lcd.print(abs(angle_pitch_buffer)/1000); //Print first number
if(lcd_loop_counter == 4)lcd.print((abs(angle_pitch_buffer)/100)%10);//Print second number
if(lcd_loop_counter == 5)lcd.print((abs(angle_pitch_buffer)/10)%10); //Print third number
if(lcd_loop_counter == 6)lcd.print("."); //Print decimal point
if(lcd_loop_counter == 7)lcd.print(abs(angle_pitch_buffer)%10); //Print decimal number
if(lcd_loop_counter == 8){
angle_roll_buffer = angle_roll_output * 10;
lcd.setCursor(6,1);
}
if(lcd_loop_counter == 9){
if(angle_roll_buffer < 0)lcd.print("-"); //Print - if value is negative
else lcd.print("+"); //Print + if value is negative
}
if(lcd_loop_counter == 10)lcd.print(abs(angle_roll_buffer)/1000); //Print first number
if(lcd_loop_counter == 11)lcd.print((abs(angle_roll_buffer)/100)%10);//Print second number
if(lcd_loop_counter == 12)lcd.print((abs(angle_roll_buffer)/10)%10); //Print third number
if(lcd_loop_counter == 13)lcd.print("."); //Print decimal point
if(lcd_loop_counter == 14)lcd.print(abs(angle_roll_buffer)%10); //Print decimal number
}
void setup_mpu_6050_registers(){
//Activate the MPU-6050
Wire.beginTransmission(0x68); //Start communicating with the MPU-6050
Wire.write(0x6B); //Send the requested starting register
Wire.write(0x00); //Set the requested starting register
Wire.endTransmission(); //End the transmission
//Configure the accelerometer (+/-8g)
Wire.beginTransmission(0x68); //Start communicating with the MPU-6050
Wire.write(0x1C); //Send the requested starting register
Wire.write(0x10); //Set the requested starting register
Wire.endTransmission(); //End the transmission
//Configure the gyro (500dps full scale)
Wire.beginTransmission(0x68); //Start communicating with the MPU-6050
Wire.write(0x1B); //Send the requested starting register
Wire.write(0x08); //Set the requested starting register
Wire.endTransmission(); //End the transmission
}
* example.c
*
* Created on: Jul 26, 2019
* Author: Itachi
*/