Mpu9250 - This device does not contain the correct signature 0x48 for a AK8963

Hello.

I´m using the mpu9250 in one of my projects. I´m using a rasperry pi 3B+ and the latest raspbian os (raspios-buster-armhf-lite 2020-08-20).

When I start and stop my application multiple times (letting it run for a couple of seconds), it sometimes happens, that I get the following exception:

“Unhandled exception. System.IO.IOException: This device does not contain the correct signature 0x48 for a AK8963”

Unfortunately there is no reliable way to reproduce the problem. It just happens sometimes. I have to power off and power on the device to get rid of that exception.

var i2cSettings = new I2cConnectionSettings(0x01, Mpu9250.DefaultI2cAddress);
_i2CMpu9250 = new Mpu9250(I2cDevice.Create(i2cSettings));

Versions used

Add following information:

• Version od dev-machine: .net core 3.1.9
• Version on RP3: .net core 3.1.8
• Version of System.Device.Gpio package: 1.1.0-prerelease.20276.1
• Version of Iot.Device.Bindings package: 1.1.0-prerelease.20276.1

[Ellerbach]

Unhandled exception. System.IO.IOException: This device does not contain the correct signature 0x48 for a AK8963

You have to access the AK8963 thru the MPU9250. See the example: https://github.com/dotnet/iot/blob/master/src/devices/Mpu9250/samples/Mpu9250.sample.cs and how the MPU9250 is accessing the AK8963: https://github.com/dotnet/iot/blob/master/src/devices/Mpu9250/Ak8963Attached.cs

The direct access is not allowed by default and doesn’t seems to work in the proper way. The MPU9250 is acting like an intermediate with the AK8963. In theory, when deactivating the MPU9250 feature of being primary device vs AK8963, it should be possible to have a direct access to the AK8963 in the same I2C line.

Please also check if the fix proposed for #1140 is working. I still don’t have the device to do the final check and fix the calibration.

[Ellerbach]

Closing this one as it should be fixed now.