Applications:
Handheld electronic instrument.
Robot orientation and position.
Navigation system.
Small size (26.5mm x 26.5mm x 11.5mm)
Light weight
High cost-effective
Easy to integrate;
Telescope position.
Auto helm rudder.
Antenna position.
Automobile GPS navigation.
Aero model position.
GY-26-USART is a low cost plane digital compass module. The working principle is utilizing magnetoresistive sensor sensing the Earth's magnetic field component, so as to get an azimuth angle. It communicate with upper computer
Through UART. Output format is ASCII. With solid state
Compass design, it has stabile operation, high accuracy and
Advanced hard iron compensation function.
Features
± 5 degree heading accuracy
Advanced hard iron calibration
Very low operating voltage(3~5VDC)
DC single supply operation
Piin number Pin name Desscription
1 VCC Power Supply Input
2 TXD Transmit Data Output
3 RXD Receive Data Input
4 SCL IIC SCL
5 SDA IIC SDA
6 GND Power and Signal Ground
7 GND Power and Signal Ground
8 GND Power and Signal Ground
9 CAL calibrate
10 NC No Connection
11 NC No Connection
12 VCC Power Supply Input
Techniicall tterms
1 Declination Anglle It is the angle between magnetic north and true north.
Declination angle of different place are different, even at the same place declination angle varies with the time. When we use compass to navigating, we get directions relative to magnetic north. So we can get directions relative to true north through declination angle compensation. For example, the current direction counted by compass is north by east 30 degrees and the declination angle is 5 degrees. So the direction relative to true north is 35 degrees (30+5° =35° )
2 Insttalllattiion Anglle
3 There is an arrowhead on the compass module and it's used to denote directions.
When installed, it requests that forward direction of the object surveyed is
Consistent with the arrowhead. So the direction counted by the compass is the
Right direction. If installing direction is not consistent with the arrowhead, there  Is a included angle and it is the deviation angle. only after we compensate it the  Compass outputs the true direction.
Calibrratiion
It's also called hard iron compensation. All digital compasses must be calibrated before used. once hard iron conditions change, the magnetic field conditions will be changed too. At this time angle information counted by the compass will be inaccurate. In order to remove the influence, it's necessary to calibrate the compass.
4 Calibratting meetthods and ffuncctions
When magnetic field changes angle information counted by compass will be in accurate.
This time it is necessary to calibrate the compass to remove the influence.
Methods:
Send "0xC0" command, and then rotate the compass two circles slowly, equably and flatly,
fast not allowed. One cycle needs more than one minute. Then send "0xC1" command to
finish calibratio
Command:
Send 0x31: (get angle)
Byte0 Byte1 Byte2 Byte3 Byte4 Byte5 Byte6 Byte7
0x0D 0x0A 0x30~0x33 0x30~0x39 0x30~0x39 0x2E 0x30~0x39 0x00~0xFF
Send 0x35: (get temperature)
Byte0 Byte1 Byte2 Byte3 Byte4 Byte5 Byte6 Byte7
0x0D 0x0A 0x30~0x33 0x30~0x39 0x30~0x39 0x2E 0x30~0x39 0x00~0xFF
Send 0xC0: (Calibration)
Byte0 Byte1 Byte2 Byte3 Byte4 Byte5 Byte6 Byte7
0x0D 0x0A 0x30 0x30 0x30 0x2E 0x30 0x05