MPU9250 with CC2650 magnetometer issues

[ajmellers]

I would just like to start by thanking you for your contributions in regards to the use of the MPU9250. We have been using the MPU9250 in conjunction with a cc2650 which on our board we have always been able to use the gyro and accelerometer on the device, recently we realised the benefits of the magnetometer and began developing firmware for such, to no avail, we then bought the development board for the MPU9250 you use with the teensy, this worked fine with your code, then using the MPU9250 board with the CC2650 then works fine with the code we had completed previously for our own chip, from this it is very difficult to decipher the issue as such, the chip is wired exactly as on the development board, are there instances of the AK8963 not working or can you advise use on what the issue is maybe?

thanks again, Alex

[ajmellers]

just to put that a little less wordy: custom board : gyro and accelerometer works fine magnetometer doesnt communicate Launchpad and mpu9250 development board : all work fine Teensy and MPU9250 dev board: all work fine

and it is definitely an mpu9250 and not just the 6250.

thank again.

[kriswiner]

Not sure what to say here. It seems the software works fine. There is no reason why the mag in the MPU9250 wouldn;t work as long as you are using the same software. Can you at least see the mag (0x0C) on the I2C bus when you do a scan? Normally, all that is required is to enable bypass mode in the INT_CFG register of the MPU9250 and this allows access to the mag.

You say a custom board. Is it possible the connections are faulty? You do have to connect certain pins to 3V3 to get the mag to work, like pin 1 and pin 22 IIRC, etc. So could be a hardware problem on your custom board most likley.

On Wed, Apr 11, 2018 at 5:03 AM, ajmellers notifications@github.com wrote:

just to put that a little less wordy: custom board : gyro and accelerometer works fine magnetometer doesnt communicate Launchpad and mpu9250 development board : all work fine Teensy and MPU9250 dev board: all work fine

and it is definitely a mpu9250 and not just the 6250,

thank again.

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[ajmellers]

Thanks for the quick reply, no the who am i does not work on the AK8963 (does on the evaluation board) both 1 and 22 are tied to VDD, yeah I think so too just not sure where!

[kriswiner]

But if you scan the I2C bus for devices, does the AK8963C appear at 0x0C? The who_am-I is 0x48, so if the auxiliary I2C bus is not enabled you won't see the mag nor be able to read from it. Did you enable the pass through mode using INT_CFG register?

What does the top of the MPU9250 pachage say? It should say MP 92...

On Wed, Apr 11, 2018 at 8:55 AM, ajmellers notifications@github.com wrote:

Thanks for the quick reply, no the who am does not work on the AK8963 (does on the evaluation board) both 1 and 22 are tied to VDD, yeah I think so too just not sure where!

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[ajmellers]

No it doesnt, when use the same code for with the launchpad (changing mpu,sda and scl pins) it works fine. Yeah enabled the INT_PIN_CFG

it should just say MP 92? Thanks again, Alex

[kriswiner]

Yes, if it is a real MPU9250 it will say MP 92 plus some other code for manufature place and date. But at the top it should say MP 92. Does it?

On Wed, Apr 11, 2018 at 9:12 AM, ajmellers notifications@github.com wrote:

No it doesnt, when use the same code for with the launchpad (changing mpu,sda and scl pins) it works fine. Yeah enabled the INT_PIN_CFG

it should just say MP 92? Thanks again, Alex

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[ajmellers]

Yeah, it says MP 92, at a loose end! thinking we may just use these boards with accelerometer and gyroscope, and move on to another chip, what would you advise? (apologies for late reply i feel we may be on different times!) Thanks again, Alex

[kriswiner]

It makes no sense that the mag doesn;t work on your board. I have never heard of such a thing after assembling hundreds of MPU9250.

You could use the LIS2MDL magnetometer from ST; it is a fine sensor as is their LSM6DSM accel/gyro and LPS22HB barometer.

If you send me the schematic portion with just the MPU9250 I might be able to find the error? One thing is to have no copper under the MPU9250 package and no thermal pad or solder on the pad. But this has to do with mag performance, and shouldn;t affect whether the mag shows on the I2C bus.

On Wed, Apr 11, 2018 at 11:01 PM, ajmellers notifications@github.com wrote:

Yeah, it says MP 92, at a loose end! thinking we may just use these boards with accelerometer and gyroscope, and move on to another chip, what would you advise? (apologies for late reply i feel we may be on different times!) Thanks again, Alex

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[ajmellers]

here is the trace of the MPU, on the right, no pad or solder underneath

On Thu, Apr 12, 2018 at 5:53 PM, Kris Winer notifications@github.com wrote:

It makes no sense that the mag doesn;t work on your board. I have never heard of such a thing after assembling hundreds of MPU9250.

You could use the LIS2MDL magnetometer from ST; it is a fine sensor as is their LSM6DSM accel/gyro and LPS22HB barometer.

If you send me the schematic portion with just the MPU9250 I might be able to find the error? One thing is to have no copper under the MPU9250 package and no thermal pad or solder on the pad. But this has to do with mag performance, and shouldn;t affect whether the mag shows on the I2C bus.

On Wed, Apr 11, 2018 at 11:01 PM, ajmellers notifications@github.com wrote:

Yeah, it says MP 92, at a loose end! thinking we may just use these boards with accelerometer and gyroscope, and move on to another chip, what would you advise? (apologies for late reply i feel we may be on different times!) Thanks again, Alex

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[kriswiner]

Not seeing any attachments. I don;t think you can attach in github. Try tleracorp@gmail.com

On Thu, Apr 12, 2018 at 9:59 AM, ajmellers notifications@github.com wrote:

here is the trace of the MPU, on the right, no pad or solder underneath

On Thu, Apr 12, 2018 at 5:53 PM, Kris Winer notifications@github.com wrote:

It makes no sense that the mag doesn;t work on your board. I have never heard of such a thing after assembling hundreds of MPU9250.

You could use the LIS2MDL magnetometer from ST; it is a fine sensor as is their LSM6DSM accel/gyro and LPS22HB barometer.

If you send me the schematic portion with just the MPU9250 I might be able to find the error? One thing is to have no copper under the MPU9250 package and no thermal pad or solder on the pad. But this has to do with mag performance, and shouldn;t affect whether the mag shows on the I2C bus.

On Wed, Apr 11, 2018 at 11:01 PM, ajmellers notifications@github.com wrote:

Yeah, it says MP 92, at a loose end! thinking we may just use these boards with accelerometer and gyroscope, and move on to another chip, what would you advise? (apologies for late reply i feel we may be on different times!) Thanks again, Alex

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