CJMCU-008 3 axis magnetometer

I’ve just received the above breakout board (see pic) from Bangood which initially I intend to use for a wind direction sensor, but cannot find any specs on it. It uses the I2C protocol so I thought I might try the Adafruit_LSM303_U.h library, but it does not recognize the device. Does anyone have experience with this board? If so I’d appreciate some direction. It has a C9UEBA sensor from ALPS on it. I’m using the Arduino Uno/Nano or the ESP32.




Post a link to the magnetometer chip data sheet.

If it is not an LSM303 chip (of which there are several different varieties) then of course the library won't recognize it.

Post a link to the magnetometer chip data sheet.

This is the only 3 axis sensor on the ALPS site. It looks the same and has the same pin labeling but has a totally different part no.

And where on the web did you find this "ALPS" site?

Is it really that much trouble to post a link?

I'm sorry. I thought I had! Realy not that much trouble! I've sent them a query and am awaiting a reply.

The HSCDTD008A is a typical magnetometer chip, for use in measuring the Earth's magnetic field, but is otherwise very different than any of the LSM303 series of chips.

How did you imagine using it to sense wind direction?

An experiment. Place the chip directly under a disc coupled to the wind vane. Place a small magnet on the north side of the disc which will rotate with wind direction. Its magnetic field should override any other magnetic field. Haven't tried it but worth a shot.

Haven't tried it but worth a shot.

Not really.

Even a small "refrigerator magnet" can have a magnetic field thousands of times greater than what that sensor is designed to measure. You will simply overload it.

To measure shaft rotation, some people use magnetic sensors designed for the purpose. Allegro Microsystems make several varieties.

Or consider the simple and cheap motor shaft encoders by Pololu, which divide the circle into 20 segments. Those would need some zero position indicator, though.

Yes, I had thought that might be the case. I thought of using a Grey code disk with opto-sensors but I was looking for a way to simplify things.

The alternative is to place the sensor on the rotating vane shaft and use the earth's magnetic field. But that requires having some electrical coupling to the device, either by wires (not practical) or a wireless connection via ESP8266, ESP32 or 24L01 (again not too practical since it will require batteries etc.).

By the way, I have answered my own previous question thanks to Google! The chip is the HSCDTD008A.

Oh well. Let's see if I can get the chip working using the datasheet info anyway.

Thanks for your input.