mpu6050_lua

mpu6050_lua.lua

-- https://invensense.tdk.com/wp-content/uploads/2015/02/MPU-6000-Register-Map1.pdf

id  = 0 
scl = 7 
sda = 6 

MPU6050SlaveAddress = 0x68

AccelScaleFactor = 4096;  --8g/s
GyroScaleFactor = 65.5; -- ± 500 °/s

MPU6050_REGISTER_SMPLRT_DIV   =  0x19
MPU6050_REGISTER_USER_CTRL    =  0x6A
MPU6050_REGISTER_PWR_MGMT_1   =  0x6B
MPU6050_REGISTER_PWR_MGMT_2   =  0x6C
MPU6050_REGISTER_CONFIG       =  0x1A
MPU6050_REGISTER_GYRO_CONFIG  =  0x1B
MPU6050_REGISTER_ACCEL_CONFIG =  0x1C
MPU6050_REGISTER_FIFO_EN      =  0x23
MPU6050_REGISTER_INT_ENABLE   =  0x38
MPU6050_REGISTER_ACCEL_XOUT_H =  0x3B
MPU6050_REGISTER_SIGNAL_PATH_RESET  = 0x68
 
function I2C_Write(deviceAddress, regAddress, data)
    i2c.start(id)       -- send start condition
    if (i2c.address(id, deviceAddress, i2c.TRANSMITTER))-- set slave address and transmit direction
    then
        print("write")
        i2c.write(id, regAddress)  -- write address to slave
        i2c.write(id, data)  -- write data to slave
        i2c.stop(id)    -- send stop condition
    else
        print("I2C_Write fails")
    end
end

function I2C_Read(deviceAddress, regAddress, SizeOfDataToRead)
    response = 0;
    i2c.start(id)       -- send start condition
    if (i2c.address(id, deviceAddress, i2c.TRANSMITTER))-- set slave address and transmit direction
    then
        i2c.write(id, regAddress)  -- write address to slave
        i2c.stop(id)    -- send stop condition
        i2c.start(id)   -- send start condition
        i2c.address(id, deviceAddress, i2c.RECEIVER)-- set slave address and receive direction
        response = i2c.read(id, SizeOfDataToRead)   -- read defined length response from slave
        i2c.stop(id)    -- send stop condition
        return response
    else
        print("I2C_Read fails")
    end
    return response
end

function unsignTosigned16bit(num)   -- convert unsigned 16-bit no. to signed 16-bit no.
    if num > 32768 then 
        num = num - 65536
    end
    return num
end

function MPU6050_Init() --configure MPU6050
    tmr.delay(150000) -- delay for 150 ms
    I2C_Write(MPU6050SlaveAddress, MPU6050_REGISTER_SMPLRT_DIV, 0x07)
    I2C_Write(MPU6050SlaveAddress, MPU6050_REGISTER_PWR_MGMT_1, 0x01)
    I2C_Write(MPU6050SlaveAddress, MPU6050_REGISTER_PWR_MGMT_2, 0x00)
    I2C_Write(MPU6050SlaveAddress, MPU6050_REGISTER_CONFIG, 0x00)
    I2C_Write(MPU6050SlaveAddress, MPU6050_REGISTER_GYRO_CONFIG, 0x08)-- set +/-500 degree/second full scale
    I2C_Write(MPU6050SlaveAddress, MPU6050_REGISTER_ACCEL_CONFIG, 0x10)-- set +/- 8g full scale  
    I2C_Write(MPU6050SlaveAddress, MPU6050_REGISTER_FIFO_EN, 0x00)
    I2C_Write(MPU6050SlaveAddress, MPU6050_REGISTER_INT_ENABLE, 0x01)
    I2C_Write(MPU6050SlaveAddress, MPU6050_REGISTER_SIGNAL_PATH_RESET, 0x00)
    I2C_Write(MPU6050SlaveAddress, MPU6050_REGISTER_USER_CTRL, 0x00)
end

i2c.setup(id, sda, scl, i2c.SLOW)   -- initialize i2c
MPU6050_Init()

tmr.delay(1000)
while true do   --read and print accelero, gyro and temperature value
    
    data = I2C_Read(MPU6050SlaveAddress, MPU6050_REGISTER_ACCEL_XOUT_H, 14)
  
    AccelX = unsignTosigned16bit((bit.bor(bit.lshift(string.byte(data, 1), 8), string.byte(data, 2))))
    AccelY = unsignTosigned16bit((bit.bor(bit.lshift(string.byte(data, 3), 8), string.byte(data, 4))))
    AccelZ = unsignTosigned16bit((bit.bor(bit.lshift(string.byte(data, 5), 8), string.byte(data, 6))))
    Temperature = unsignTosigned16bit(bit.bor(bit.lshift(string.byte(data,7), 8), string.byte(data,8)))
    GyroX = unsignTosigned16bit((bit.bor(bit.lshift(string.byte(data, 9), 8), string.byte(data, 10))))
    GyroY = unsignTosigned16bit((bit.bor(bit.lshift(string.byte(data, 11), 8), string.byte(data, 12))))
    GyroZ = unsignTosigned16bit((bit.bor(bit.lshift(string.byte(data, 13), 8), string.byte(data, 14))))
 
    -- ACC in g unit, Temp  in degree/celcius, Gyro in degree/celcius
    AccelX = AccelX/AccelScaleFactor   -- divide each with their sensitivity scale factor
    AccelY = AccelY/AccelScaleFactor
    AccelZ = AccelZ/AccelScaleFactor
    Temperature = Temperature/340.0+36.53-- temperature formula
    GyroX = GyroX/GyroScaleFactor
    GyroY = GyroY/GyroScaleFactor
    GyroZ = GyroZ/GyroScaleFactor
    
    print(string.format("TUO-Ax:%.3g Ay:%.3g Az:%.3g T:%.3g Gx:%.3g Gy:%.3g Gz:%.3g",
                        AccelX, AccelY, AccelZ, Temperature, GyroX, GyroY, GyroZ))
    tmr.delay(100000)   -- 100ms timer delay
end