Reset FIFO and DMP

Question

Reset FIFO and DMP

Opened this issue 8 months ago · 5 comments

There is a line in the acc/gyr calibration function
writeByte(MPU9250_ADDRESS, MPU9250_USER_CTRL, 0x0C); // Reset FIFO and DMP
Why value is 0x0C and not 0x6?
0x0C = 0b1100
Bits 2 and 3 are high
But according to documentation for USER_CTRL, bit 3 is Reserved

Answer 1 · 2023-11-12T16:27:45.000Z

Long story short, Invensense didn't expose DMP control register bits in their public MPU9250 documents. So bit 3 is DMP reset. You can use 0x06, or try both and see what difference it makes (none on power-up initialization), or consult the Motion_Sense code to see how Invensense does this, or find a MPU9250 DMP application note to see how to use this register bit, etc.

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On Sat, Nov 11, 2023 at 11:47 PM Mark Berner ***@***.***> wrote: There is a line in the acc/gyr calibration function writeByte(MPU9250_ADDRESS, MPU9250_USER_CTRL, 0x0C); // Reset FIFO and DMP Why value is 0x0C and not 0x6? 0x0C = 0b1100 Bits 2 and 3 are high But according to documentation for USER_CTRL, bit 3 is Reserved [image: Screenshot 2023-11-12 at 9 43 38] <https://user-images.githubusercontent.com/539063/282285459-07d71ae7-e775-465f-91eb-c6ca9f561d98.png> — Reply to this email directly, view it on GitHub <#492>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ABTDLKQDPWGCHUKM5AMHTETYEB5H7AVCNFSM6AAAAAA7H2SFZ2VHI2DSMVQWIX3LMV43ASLTON2WKOZRHE4DSMRZGE2TSNY> . You are receiving this because you are subscribed to this thread.Message ID: ***@***.***>

Answer 2 · 2023-11-12T18:38:15.000Z

Thanks for quick answer and great repository

I have another question about calibration

I'm porting this code to rust for Pico 10DOF IMU
There is a code - writing accelerometer biases, for me it works when I comment out this code only

// Apparently this is not working for the acceleration biases in the MPU-9250 // Are we handling the temperature correction bit properly? // Push accelerometer biases to hardware registers writeByte(MPU9250_ADDRESS, XA_OFFSET_H, data[0]); writeByte(MPU9250_ADDRESS, XA_OFFSET_L, data[1]); writeByte(MPU9250_ADDRESS, YA_OFFSET_H, data[2]); writeByte(MPU9250_ADDRESS, YA_OFFSET_L, data[3]); writeByte(MPU9250_ADDRESS, ZA_OFFSET_H, data[4]); writeByte(MPU9250_ADDRESS, ZA_OFFSET_L, data[5]);
Thanks

Answer 3 · 2023-11-12T18:45:44.000Z

What is the question?

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On Sun, Nov 12, 2023 at 10:38 AM Mark Berner ***@***.***> wrote: Thanks for quick answer and great repository I have another question about calibration I'm porting this code to rust for Pico 10DOF IMU There is a code - writing accelerometer biases, for me it works when I comment out this code only // Apparently this is not working for the acceleration biases in the MPU-9250 // Are we handling the temperature correction bit properly? // Push accelerometer biases to hardware registers writeByte(MPU9250_ADDRESS, XA_OFFSET_H, data[0]); writeByte(MPU9250_ADDRESS, XA_OFFSET_L, data[1]); writeByte(MPU9250_ADDRESS, YA_OFFSET_H, data[2]); writeByte(MPU9250_ADDRESS, YA_OFFSET_L, data[3]); writeByte(MPU9250_ADDRESS, ZA_OFFSET_H, data[4]); writeByte(MPU9250_ADDRESS, ZA_OFFSET_L, data[5]); — Reply to this email directly, view it on GitHub <#492 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ABTDLKU5RMQGZZRLTI5HRILYEEJSFAVCNFSM6AAAAAA7H2SFZ2VHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMYTQMBXGIYDMNBXGY> . You are receiving this because you commented.Message ID: ***@***.***>

Answer 4 · 2023-11-12T18:50:00.000Z

Sorry, should I expect it works properly if I write accelerometer biases or on some boards it will not work.
(on some ino files this code commented out)
I'm new with IMU.

Answer 5 · 2023-11-12T19:05:15.000Z

This technically works, that is, you should be able to write the accel biases to the appropriate registers, but I have found the results to be unsatisfactory since the LSB is serves double duty as some sort of indicator bit such that the biases can be slightly off. So I apply accel biases in the main loop. The gyro bias registers work fine.

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On Sun, Nov 12, 2023 at 10:50 AM Mark Berner ***@***.***> wrote: Sorry, should I expect it works properly if I write accelerometer biases or on some boards it will not work. (on some *ino* files this code commented out) I'm new with IMU. — Reply to this email directly, view it on GitHub <#492 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ABTDLKR55CXZXJTTZCPHOC3YEEK6FAVCNFSM6AAAAAA7H2SFZ2VHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMYTQMBXGIYDSMBZHE> . You are receiving this because you commented.Message ID: ***@***.***>