Hello, I would like to get a heading value from HMC5883L. The values I am getting are strange and unexpected. I am using the correct declination angle and there are no magnetic elements around the sensor (see photo). I have used this sensor in an arduino quadcopter with my flight controller and it worked fine without the need for any offsets. Any ideas? (It looks like a magnetometer sensitivity problem and heading scale at all) Image on google drive: https://drive.google.com/file/d/1eI0mKh … sp=sharing
Sample code:
Code: Select all
import smbus
import math
import time
HMC5883L_ADDRESS = 0x1E
CONFIG_REGISTER_A = 0x00
CONFIG_REGISTER_B = 0x01
MODE_REGISTER = 0x02
DATA_X_MSB = 0x03
DATA_X_LSB = 0x04
DATA_Z_MSB = 0x05
DATA_Z_LSB = 0x06
DATA_Y_MSB = 0x07
DATA_Y_LSB = 0x08
declination = 5.75
bus = smbus.SMBus(1)
def setup_hmc5883l():
bus.write_byte_data(HMC5883L_ADDRESS, MODE_REGISTER, 0x00)
def read_raw_data(register):
high = bus.read_byte_data(HMC5883L_ADDRESS, register)
low = bus.read_byte_data(HMC5883L_ADDRESS, register + 1)
value = (high << 8) + low
if value > 32767:
value -= 65536
return value
def read_hmc5883l():
x = read_raw_data(DATA_X_MSB)
z = read_raw_data(DATA_Z_MSB)
y = read_raw_data(DATA_Y_MSB)
heading_rad = math.atan2(y, x)
heading_rad += math.radians(declination)
if heading_rad < 0:
heading_rad += 2 * math.pi
heading_deg = math.degrees(heading_rad)
return heading_deg
if __name__ == "__main__":
try:
setup_hmc5883l()
while True:
heading = read_hmc5883l()
print(f"Heading: {heading:.2f} degrees")
time.sleep(1)
except KeyboardInterrupt:
print("konec")
