mpu9250 magnetometer zero readings

RE: mpu9250 magnetometer zero readings

vam5104 — Wed, 27 Dec 2017 19:35:14 GMT

Hi, Thank you for the help. The problem has been solved. The issue was with my mpu9250. I changed it and I was able to obtain the output.

RE: mpu9250 magnetometer zero readings

endnode — Sun, 24 Dec 2017 22:55:55 GMT

I see the problem very simple: there is some embedded sensor module/chip which has defined some wired (serial) interface over TWI/I2C/SPI/QSPI/UART/whatever. You should attach logical analyzer to the wires and simply compare what you see (= what you send from nRF5x chip as master) with what is written and shown on examples in specification of that sensor. I bet you will see the problem straight away. If you want us to do this comparison job for you then at least provide us with these traces from wired interface (sorry but "I verified and it was right" doesn't look very convincing here if it doesn't work;).

RE: mpu9250 magnetometer zero readings

vam5104 — Sun, 24 Dec 2017 19:53:56 GMT

No, the issue has not been resolved. Here’s what I found out about it.

Mpu9250 uses imu6500 and ak8963. So, I changed the code such that the magnetometer part of app_mpu.h accepts only mpu9250.
I’m unable to read or write the magnetometer. It might be because of having ak8963_adr wrongly defined. However, I verified it and it was right (0x0C). All the other registers were defined correctly.
I get 0s because the magn read and write functions doesn’t work at all.

I’m working on it continuously. Any help will be greatly appreciated.

RE: mpu9250 magnetometer zero readings

vam5104 — Sun, 24 Dec 2017 19:53:03 GMT

No, the issue has not been resolved. Here’s what I found out about it.

Mpu9250 uses imu6500 and ak8963. So, I changed the code such that the magnetometer part of app_mpu.h accepts only mpu9250.
I’m unable to read or write the magnetometer. It might be because of having ak8963_adr wrongly defined. However, I verified it and it was right (0x0C). All the other registers were defined correctly.
I get 0s because the magn read and write functions doesn’t work at all.

I’m working on it continuously. Any help will be greatly appreciated.

RE: mpu9250 magnetometer zero readings

endnode — Sun, 24 Dec 2017 14:52:16 GMT

Does it mean the issue is resolved? If so please close the question.

RE: mpu9250 magnetometer zero readings

vam5104 — Sun, 24 Dec 2017 12:43:01 GMT

Well, I did that. I was able to find that as long as I keep calling magnetometer functions, mpu doesnt respond. If i removed, then i get the acc and gyro values without any issues.

RE: mpu9250 magnetometer zero readings

endnode — Sat, 23 Dec 2017 22:55:58 GMT

So then put logical analyzer or oscilloscope to these wires and check what exactly you read. Assuming you will see that lines are not performing clock and data as expected (no real values read) you should consult general I2C/TXI tutorials and spec sheet of your sensor chip to see what is exactly wrong.

RE: mpu9250 magnetometer zero readings

vam5104 — Sat, 23 Dec 2017 14:45:57 GMT

I connected it via I2C/TWI.

RE: mpu9250 magnetometer zero readings

Matt — Sat, 23 Dec 2017 14:34:41 GMT

How do you connect the MPU9250 to the PCA10040? uart? SPI? I2C?