|The GY-273 is basically a Honeywell HMC5883L chip (datasheet). Note: this is a 3 Vdc chip. You must install a level-shifter to connect to an Arduino. Since the power drawn is about 100 µA you can easily use the voltage shifter also as power supply. The I²C write address is 3C and the read address is 3D. A measurement takes about 6 ms. The DRDY pin is a status bit and tells you whether it is safe to read the compass value. Data Ready pin is internally pulled high but low for 250 μsec after fresh data is placed in the data output registers. |
When powered on the GY-273 is in Single-Measurement Mode by default. In this mode you have the lowest power consumption but more software actions needed. Since the power consumption is only 100 µA most roboteers change the Mode to Continuous Measurement Mode during setup.
The last trick is how to calculate a heading from the data obtained by the compass module. diydrones.com.
The CMPS03 (data-sheet) used to be the only compass offered until about around the turn of the millennium. It is still available (2016) but we don`t use it anymore. For robots this compass has several disadvantages. It is not tilt compensated and it is also rather expensive (€ 29,94). The I²C address of the CMPS03 compass module is C0 (sketch).