Using DMP to receive multiple sensor data values -

[n2d7]

Many thanks for adding the DMP support for this library.
I followed the recent example Example5_DMP_Quat9_Orientation and was successful getting the quaternion values from the sensor as the example shows. However, I would also want to get multiple data values at the same time, including quaternions and raw accel,gyro,mag data.
To test it out, I added the following lines in the setup;

success &= (myICM.enableDMPSensor(INV_ICM20948_SENSOR_ACCELEROMETER) == ICM_20948_Stat_Ok);
success &= (myICM.setDMPODRrate(DMP_ODR_Reg_Accel, 200) == ICM_20948_Stat_Ok);

and in the loop

else if ((data.header & DMP_header_bitmap_Accel) > 0)
{

	float acc_x = ((float)data.Raw_Accel.Data.X); 
	float acc_y = ((float)data.Raw_Accel.Data.Y); 
	float acc_z = ((float)data.Raw_Accel.Data.Z); 

	char sensor_string_buff[128];
	sprintf(sensor_string_buff, "{\"accel_x\":%f, \"accel_y\":%f, \"accel_z\":%f}", acc_x,acc_y,acc_z);
	Serial.println(sensor_string_buff);
}

However, I am not getting any data (both quaternion and accel values), and it seems like the fifo is empty.
When reading the data if ((myICM.status == ICM_20948_Stat_Ok) || (myICM.status == ICM_20948_Stat_FIFOMoreDataAvail)) is always false.
Appreciate any help to fix this.

[PaulZC]

Hi @n2d7 ,

As you can probably tell, we're still gaining experience with the DMP and so we're not 100% confident on how to use it. Also, InvenSense admit that the documentation is not complete (which is why they don't want to release it openly).
Let me give you some suggestions:

I've updated the comments in the DMP example to give more information on which combination of sensors are enabled for each mode.

success &= (myICM.enableDMPSensor(INV_ICM20948_SENSOR_ACCELEROMETER) == ICM_20948_Stat_Ok);
success &= (myICM.setDMPODRrate(DMP_ODR_Reg_Accel, 200) == ICM_20948_Stat_Ok);

This should work fine and should enable the raw accelerometer output (via the FIFO). You may need to try lower rates than 200. Try 12 or 50 and see if that works. Try INV_ICM20948_SENSOR_RAW_ACCELEROMETER too - but it seems to load the same value into DATA_OUT_CTL1 so I really don't understand the difference.

Your loop code looks good. Yes, I do think you need to check for:

else if ((data.header & DMP_header_bitmap_Accel) > 0)

and, yes, the accel data should be returned in:

data.Raw_Accel.Data.X

etc.. (Great detective work!)

So, I'm not quite sure what is going wrong...

What I plan to do next is to run @ericalbers port of the InvenSense example, capture the SPI data so I can see exactly which registers are being set and with what values, and then make sure that my code is doing the same thing. It is very possible that we have missed a configuration step. (The InvenSense example code is very opaque and, like I said, InvenSense admit the documentation isn't complete.)

Please let me know what you find!
Best wishes,
Paul

[n2d7]

Hi PaulZC,
Thank you very much for your prompt answer. And I really appreciate the effort that you put in to this work.
I will try it with lower rates to see if it works.

I also tested this with 2 IMUs in the same SPI bus. It seems to be working well after checking the incoming quaternion values with a gui application.

Also, is it possible to read the quaternion values directly from the DMP without using the fifo?

[PaulZC]

Hi @n2d7 ,
I think the DMP can only write to the FIFO. Or that‘s my understanding at the moment.
It will be a few days before I can try capturing the SPI (or I2C) data from @ericalbers code and do a write-by-write comparison. If you have the time and the curiosity to try it, please do. I’d really appreciate it.
Best wishes,
Paul

[PaulZC]

Hi @n2d7 ,
Just for interest, here's a summary of the I2C traffic from @ericalbers's port of the InvenSense example. There are a few surprises in there and it has highlighted a few gremlins in my version of the code. I'll go through this in a day or two and will update my code to match.
Enjoy!
Paul

/* 
 *  From @ericalbers port of the InvenSense example (https://github.com/ericalbers/ICM20948_DMP_Arduino)
 *  The eric + InvenSense code configures the ICM-20948 (via I2C) as follows:
 *  
 *  Select and read register 0x00 (WhoAmI)
 *  ICM returns 0xEA
 *  Set register 0x06 (Power Management 1) to 0x01 (Auto clock)
 *  Select and read register 0x03 (User Control)
 *  ICM returns 0xC0
 *  Set register 0x07 (Power Management 2) to 0x47 (Reserved bit 6 set. Disable all Gyro axes)
 *  Select and read register 0x00 (WhoAmI)
 *  ICM returns 0xEA
 *  Set register 0x05 (Low Power Configuration) to 0x70 (I2C Master, Accel and Gyro in duty cycled mode)
 *  Set register 0x03 (User Control) to 0x00 (Disable DMP, disable FIFO, disable I2C Master)
 *  Set register 0x7C (Memory Start Address) to 0x90
 *  .....
 *  Write DMP firmware data to register 0x7D (Memory Read/Write) in blocks of 16 bytes
 *  During write, increment register 0x7E (Memory Bank Select) every 256 bytes
 *  .....
 *  Verify DMP firmware by reading it all back again
 *  .....
 *  Select and read register 0x7F (Register Bank Select) 
 *  ICM returns 0x00
 *  Set register 0x7F (Register Bank Select) to 0x20 == Bank 2
 *  Write 0x1000 to register 0x50 (Program Start Address High) (Magic Number)
 *  Set register 0x7F (Register Bank Select) to 0x00 == Bank 0
 *  Set register 0x7E (Memory Bank Select) to 0x00
 *  Set register 0x7C (Memory Start Address) to 0x40
 *  Write 0x0000 to memory (Data Out Control 1) (Disable all DMP features)
 *  Set register 0x7C (Memory Start Address) to 0x42
 *  Write 0x0000 to memory (Data Out Control 2) (Disable all "header2" features)
 *  Set register 0x7C (Memory Start Address) to 0x4C
 *  Write 0x0000 to memory (Data Interrupt Control) (Disable DMP interrupts)
 *  Set register 0x7C (Memory Start Address) to 0x4E
 *  Write 0x0000 to memory (FIFO Watermark) (Set watermark to zero)
 *  Set register 0x7C (Memory Start Address) to 0x8A
 *  Write 0x0000 to memory (Data Ready Status) (Disable all data ready indicators)
 *  Set register 0x7E (Memory Bank Select) to 0x01
 *  Set register 0x7C (Memory Start Address) to 0xFE
 *  Write 0x0320 to memory (31 * 16 + 14 = FIFO Watermark) (Set FIFO watermark to 800)
 *  Set register 0x10 (Reg Interrupt Enable) to 0x02 (Enable DMP interrupt to interrupt pin)
 *  Set register 0x12 (Reg Interrupt Enable 2) to 0x01 (Enable interrupt for FIFO overflow - 'channel' 0 only)
 *  Set register 0x26 (Single FIFO Priority Select) to 0xE4 (Worth investigating?)
 *  Select and read register 0x75 (Hardware Fix Disable) 
 *  ICM returns 0x48
 *  Set register 0x75 (Hardware Fix Disable) to 0x48 (Worth investigating?)
 *  Select and read register 0x7F (Register Bank Select)
 *  ICM returns 0x00
 *  Set register 0x7F (Register Bank Select) to 0x20 == Bank 2
 *  Set register 0x00 (Gyro Sample Rate Divider) to 0x13
 *  Write 0x0013 to 0x10 (Accelerometer Sample Rate Divider 1&2)
 *  Select and read register 0x7F (Register Bank Select)
 *  ICM returns 0x20
 *  Set register 0x7F (Register Bank Select) to 0x00 == Bank 0
 *  Set register 0x7E (Memory Bank Select) to 0x03
 *  Set register 0x7C (Memory Start Address) to 0x0A
 *  Write 0x0000 to memory (48 * 16 + 10 = BAC Rate)
 *  Set register 0x7C (Memory Start Address) to 0x08
 *  Write 0x0000 to memory (48 * 16 + 8 = B2S Rate)
 *  Set register 0x76 (FIFO Config) to 0x00
 *  Set register 0x68 (FIFO Reset) to 0x1F
 *  Set register 0x68 (FIFO Reset) to 0x1E
 *  Set register 0x66 (FIFO Enable 1) to 0x00
 *  Set register 0x67 (FIFO Enable 2) to 0x00
 *  Set register 0x06 (Power Management 1) to 0x21
 *  Set register 0x07 (Power Management 2) to 0x7F
 *  Set register 0x06 (Power Management 1) to 0x61
 *  Set register 0x06 (Power Management 1) to 0x21
 *  Set register 0x06 (Power Management 1) to 0x01
 *  Select and read register 0x7F (Register Bank Select)
 *  ICM returns 0x00
 *  Set register 0x7F (Register Bank Select) to 0x30 == Bank 3
 *  Set register 0x05 (Peripheral 0 Control) to 0x00
 *  Set register 0x09 (Peripheral 1 Control) to 0x00
 *  Set register 0x0D (Peripheral 2 Control) to 0x00
 *  Set register 0x11 (Peripheral 3 Control) to 0x00
 *  Set register 0x01 (Master Control) to 0x10
 *  Set register 0x00 (Master ODR Config) to 0x04
 *  Set register 0x03 (Master Delay Control) to 0x8C
 *  Set register 0x04 (Peripheral 0 Register) to 0x00
 *  Set register 0x05 (Peripheral 0 Control) to 0x81
 *  Select and read register 0x7F (Register Bank Select)
 *  ICM returns 0x30
 *  Set register 0x7F (Register Bank Select) to 0x00 == Bank 0
 *  Set register 0x03 (User Control) to 0x20
 *  #####
 *  #####
 *  #####
 *  Set register 0x03 (User Control) to 0x00
 *  Select and read register 0x3B (Ext Peripheral Sensor Data)
 *  ICM returns 0x48
 *  Select and read register 0x7F (Register Bank Select)
 *  ICM returns 0x00
 *  Set register 0x7F (Register Bank Select) to 0x30 == Bank 3
 *  Set register 0x05 (Peripheral 0 Control) to 0x00
 *  Set register 0x07 (Peripheral 1 Address) to 0x0C
 *  Set register 0x08 (Peripheral 1 Register) to 0x31
 *  Set register 0x0A (Peripheral 1 Data) to 0x00
 *  Set register 0x09 (Peripheral 1 Control) to 0x81
 *  Select and read register 0x7F (Register Bank Select)
 *  ICM returns 0x30
 *  Set register 0x7F (Register Bank Select) to 0x00 == Bank 0
 *  Set register 0x03 (User Control) to 0x20
 *  #####
 *  #####
 *  #####
 *  Set register 0x03 (User Control) to 0x00
 *  Select and read register 0x7F (Register Bank Select)
 *  ICM returns 0x00
 *  Set register 0x7F (Register Bank Select) to 0x30 == Bank 3
 *  Set register 0x09 (Peripheral 1 Control) to 0x00
 *  Set register 0x05 (Peripheral 0 Control) to 0x00
 *  Set register 0x09 (Peripheral 1 Control) to 0x00
 *  Select and read register 0x7F (Register Bank Select)
 *  ICM returns 0x30
 *  Set register 0x7F (Register Bank Select) to 0x00 == Bank 0
 *  Set register 0x03 (User Control) to 0x00
 *  Set register 0x7E (Memory Bank Select) to 0x01
 *  Set register 0x7C (Memory Start Address) to 0x70
 *  Write 0x09999999 to memory (23 * 16 + 0 = Compass Matrix 00)
 *  Set register 0x7C (Memory Start Address) to 0x74
 *  Write 0x00000000 to memory (23 * 16 + 4 = Compass Matrix 01)
 *  Set register 0x7C (Memory Start Address) to 0x78
 *  Write 0x00000000 to memory (23 * 16 + 8 = Compass Matrix 02)
 *  Set register 0x7C (Memory Start Address) to 0x7C
 *  Write 0x00000000 to memory (23 * 16 + 12 = Compass Matrix 10)
 *  Set register 0x7C (Memory Start Address) to 0x80
 *  Write 0xF6666667 to memory (24 * 16 + 0 = Compass Matrix 11)
 *  Set register 0x7C (Memory Start Address) to 0x84
 *  Write 0x00000000 to memory (24 * 16 + 4 = Compass Matrix 12)
 *  Set register 0x7C (Memory Start Address) to 0x88
 *  Write 0x00000000 to memory (24 * 16 + 8 = Compass Matrix 20)
 *  Set register 0x7C (Memory Start Address) to 0x8C
 *  Write 0x00000000 to memory (24 * 16 + 12 = Compass Matrix 21)
 *  Set register 0x7C (Memory Start Address) to 0x90
 *  Write 0xF6666667 to memory (25 * 16 + 0 = Compass Matrix 22)
 *  Set register 0x06 (Power Management 1) to 0x21
 *  Set register 0x06 (Power Management 1) to 0x01
 *  Set register 0x7E (Memory Bank Select) to 0x0D
 *  Set register 0x7C (Memory Start Address) to 0x00
 *  Write 0x40000000 to memory (208 * 16 + 0 = B2S Mounting Matrix 00)
 *  Set register 0x06 (Power Management 1) to 0x21
 *  Set register 0x06 (Power Management 1) to 0x01
 *  Set register 0x7C (Memory Start Address) to 0x04
 *  Write 0x00000000 to memory (208 * 16 + 4 = B2S Mounting Matrix 01)
 *  Set register 0x06 (Power Management 1) to 0x21
 *  Set register 0x06 (Power Management 1) to 0x01
 *  Set register 0x7C (Memory Start Address) to 0x08
 *  Write 0x00000000 to memory (208 * 16 + 8 = B2S Mounting Matrix 02)
 *  Set register 0x06 (Power Management 1) to 0x21
 *  Set register 0x06 (Power Management 1) to 0x01
 *  Set register 0x7C (Memory Start Address) to 0x0C
 *  Write 0x00000000 to memory (208 * 16 + 12 = B2S Mounting Matrix 10)
 *  Set register 0x06 (Power Management 1) to 0x21
 *  Set register 0x06 (Power Management 1) to 0x01
 *  Set register 0x7C (Memory Start Address) to 0x10
 *  Write 0x40000000 to memory (209 * 16 + 0 = B2S Mounting Matrix 11)
 *  Set register 0x06 (Power Management 1) to 0x21
 *  Set register 0x06 (Power Management 1) to 0x01
 *  Set register 0x7C (Memory Start Address) to 0x14
 *  Write 0x00000000 to memory (209 * 16 + 4 = B2S Mounting Matrix 12)
 *  Set register 0x06 (Power Management 1) to 0x21
 *  Set register 0x06 (Power Management 1) to 0x01
 *  Set register 0x7C (Memory Start Address) to 0x18
 *  Write 0x00000000 to memory (209 * 16 + 8 = B2S Mounting Matrix 20)
 *  Set register 0x06 (Power Management 1) to 0x21
 *  Set register 0x06 (Power Management 1) to 0x01
 *  Set register 0x7C (Memory Start Address) to 0x1C
 *  Write 0x00000000 to memory (209 * 16 + 12 = B2S Mounting Matrix 21)
 *  Set register 0x06 (Power Management 1) to 0x21
 *  Set register 0x06 (Power Management 1) to 0x01
 *  Set register 0x7C (Memory Start Address) to 0x20
 *  Write 0x40000000 to memory (210 * 16 + 0 = B2S Mounting Matrix 22)
 *  Set register 0x06 (Power Management 1) to 0x21
 *  Set register 0x06 (Power Management 1) to 0x01
 *  Set register 0x7C (Memory Start Address) to 0x00
 *  Write 0x40000000 to memory (208 * 16 + 0 = B2S Mounting Matrix 00)
 *  .....
 *  Select and read register 0x7F (Register Bank Select)
 *  ICM returns 0x00
 *  Set register 0x7F (Register Bank Select) to 0x20 == Bank 2
 *  Select and read register 0x14 (Accel Config)
 *  ICM returns 0x02
 *  Select and read register 0x7F (Register Bank Select)
 *  ICM returns 0x20
 *  Set register 0x7F (Register Bank Select) to 0x00 == Bank 0
 *  Set register 0x06 (Power Management 1) to 0x21
 *  Set register 0x06 (Power Management 1) to 0x01
 *  Select and read register 0x7F (Register Bank Select)
 *  ICM returns 0x00
 *  Set register 0x7F (Register Bank Select) to 0x20 == Bank 2
 *  Set register 0x14 (Accel Config) to 0x02
 *  Select and read register 0x7F (Register Bank Select)
 *  ICM returns 0x20
 *  Set register 0x7F (Register Bank Select) to 0x00 == Bank 0
 *  Set register 0x06 (Power Management 1) to 0x21
 *  Set register 0x06 (Power Management 1) to 0x01
 *  Select and read register 0x7F (Register Bank Select)
 *  ICM returns 0x00
 *  Set register 0x7F (Register Bank Select) to 0x20 == Bank 2
 *  Select and read register 0x15 (Accel Config 2)
 *  ICM returns 0x00
 *  Select and read register 0x7F (Register Bank Select)
 *  ICM returns 0x20
 *  Set register 0x7F (Register Bank Select) to 0x00 == Bank 0
 *  Set register 0x06 (Power Management 1) to 0x21
 *  Set register 0x06 (Power Management 1) to 0x01
 *  Select and read register 0x7F (Register Bank Select)
 *  ICM returns 0x00
 *  Set register 0x7F (Register Bank Select) to 0x20 == Bank 2
 *  Set register 0x15 (Accel Config 2) to 0x00
 *  Select and read register 0x7F (Register Bank Select)
 *  ICM returns 0x20
 *  Set register 0x7F (Register Bank Select) to 0x00 == Bank 0
 *  Set register 0x06 (Power Management 1) to 0x21
 *  Set register 0x06 (Power Management 1) to 0x01
 *  Set register 0x7E (Memory Bank Select) to 0x01
 *  Set register 0x7C (Memory Start Address) to 0xE0
 *  Write 0x40000000 to memory (30 * 16 + 0 = Accelerometer Scale)
 *  Set register 0x06 (Power Management 1) to 0x21
 *  Set register 0x06 (Power Management 1) to 0x01
 *  Set register 0x7E (Memory Bank Select) to 0x04
 *  Set register 0x7C (Memory Start Address) to 0xF4
 *  Write 0x00040000 to memory (79 * 16 + 4 = Accelerometer Scale 2)
 *  Set register 0x06 (Power Management 1) to 0x21
 *  Set register 0x06 (Power Management 1) to 0x01
 *  Select and read register 0x7F (Register Bank Select)
 *  ICM returns 0x00
 *  Set register 0x7F (Register Bank Select) to 0x20 == Bank 2
 *  Select and read register 0x14 (Accel Config)
 *  ICM returns 0x02
 *  Select and read register 0x7F (Register Bank Select)
 *  ICM returns 0x20
 *  Set register 0x7F (Register Bank Select) to 0x00 == Bank 0
 *  Set register 0x06 (Power Management 1) to 0x21
 *  Set register 0x06 (Power Management 1) to 0x01
 *  Select and read register 0x7F (Register Bank Select)
 *  ICM returns 0x00
 *  Set register 0x7F (Register Bank Select) to 0x20 == Bank 2
 *  Set register 0x14 (Accel Config) to 0x02
 *  Select and read register 0x7F (Register Bank Select)
 *  ICM returns 0x20
 *  Set register 0x7F (Register Bank Select) to 0x00 == Bank 0
 *  Set register 0x06 (Power Management 1) to 0x21
 *  Set register 0x06 (Power Management 1) to 0x01
 *  Select and read register 0x7F (Register Bank Select)
 *  ICM returns 0x00
 *  Set register 0x7F (Register Bank Select) to 0x20 == Bank 2
 *  Select and read register 0x15 (Accel Config 2)
 *  ICM returns 0x00
 *  Select and read register 0x7F (Register Bank Select)
 *  ICM returns 0x20
 *  Set register 0x7F (Register Bank Select) to 0x00 == Bank 0
 *  Set register 0x06 (Power Management 1) to 0x21
 *  Set register 0x06 (Power Management 1) to 0x01
 *  Select and read register 0x7F (Register Bank Select)
 *  ICM returns 0x00
 *  Set register 0x7F (Register Bank Select) to 0x20 == Bank 2
 *  Set register 0x15 (Accel Config 2) to 0x00
 *  .....
 *  Set register 0x7E (Memory Bank Select) to 0x01
 *  Set register 0x7C (Memory Start Address) to 0xE0
 *  Write 0x04000000 to memory (30 * 16 + 0 = Accelerometer Scale)
 *  .....
 *  Set register 0x7E (Memory Bank Select) to 0x04
 *  Set register 0x7C (Memory Start Address) to 0xF4
 *  Write 0x00040000 to memory (79 * 16 + 4 = Accelerometer Scale 2)
 *  .....
 *  Select and read register 0x7F (Register Bank Select)
 *  ICM returns 0x00
 *  Set register 0x7F (Register Bank Select) to 0x20 == Bank 2
 *  Select and read register 0x01 (Gyro Config 1)
 *  ICM returns 0x07
 *  .....
 *  Set register 0x01 (Gyro Config 1) to 0x07
 *  .....
 *  Select and read register 0x02 (Gyro Config 2)
 *  ICM returns 0x00
 *  .....
 *  Set register 0x02 (Gyro Config 2) to 0x00
 *  .....
 *  Set register 0x7F (Register Bank Select) to 0x10 == Bank 1
 *  Select and read register 0x28 (Timebase Correction PLL)
 *  ICM returns 0x18
 *  .....
 *  Set register 0x7E (Memory Bank Select) to 0x01
 *  Set register 0x7C (Memory Start Address) to 0x30
 *  Write 0x26FAB4B1 to memory (19 * 16 + 0 = Gyro Scaling Factor)
 *  .....
 *  Set register 0x7E (Memory Bank Select) to 0x04
 *  Set register 0x7C (Memory Start Address) to 0x8C
 *  Write 0x10000000 to memory (72 * 16 + 12 = Gyro Fullscale)
 *  .....
 *  Set register 0x7F (Register Bank Select) to 0x20 == Bank 2
 *  Select and read register 0x01 (Gyro Config 1)
 *  ICM returns 0x07
 *  .....
 *  Set register 0x01 (Gyro Config 1) to 0x07
 *  .....
 *  Select and read register 0x02 (Gyro Config 2)
 *  ICM returns 0x00
 *  .....
 *  Set register 0x02 (Gyro Config 2) to 0x00
 *  .....
 *  Set register 0x7C (Memory Start Address) to 0x8C
 *  Write 0x10000000 to memory (72 * 16 + 12 = Gyro Fullscale)
 *  .....
 *  Set register 0x7F (Register Bank Select) to 0x20 == Bank 2
 *  Select and read register 0x01 (Gyro Config 1)
 *  ICM returns 0x07
 *  .....
 *  Set register 0x01 (Gyro Config 1) to 0x07
 *  .....
 *  Select and read register 0x02 (Gyro Config 2)
 *  ICM returns 0x00
 *  .....
 *  Set register 0x02 (Gyro Config 2) to 0x00
 *  .....
 *  Set register 0x7F (Register Bank Select) to 0x00 == Bank 0
 *  .....
 *  Set register 0x7C (Memory Start Address) to 0x8C
 *  Write 0x10000000 to memory (72 * 16 + 12 = Gyro Fullscale)
 *  Set register 0x06 (Power Management 1) to 0x21
 *  .....
 *  Set register 0x07 (Power Management 2) to 0x47
 *  Set register 0x06 (Power Management 1) to 0x01
 *  Set register 0x03 (User Control) to 0xC0
 *  Set register 0x7E (Memory Bank Select) to 0x00
 *  Set register 0x7C (Memory Start Address) to 0x40
 *  Write 0x4048 to memory (4 * 16 + 0 == Data Out Control 1)
 *  Set register 0x7C (Memory Start Address) to 0x4C
 *  Write 0x4048 to memory (4 * 16 + 12 == Data Interrupt Control)
 *  Set register 0x7C (Memory Start Address) to 0x42
 *  Write 0x2000 to memory (4 * 16 + 2 == Data Out Control 2)
 *  Set register 0x7C (Memory Start Address) to 0x4E
 *  Write 0x0100 to memory (4 * 16 + 14 == Motion Event Control)
 *  .....
 *  Set register 0x7F (Register Bank Select) to 0x20 == Bank 2
 *  Set register 0x00 (Gyro Sample Rate Divider) to 0xE0
 *  .....
 *  Set register 0x7F (Register Bank Select) to 0x00 == Bank 0
 *  Set register 0x7C (Memory Start Address) to 0xBA
 *  Write 0x0000 to memory (11 * 16 + 10 == ODR Gyro)
 *  Set register 0x7C (Memory Start Address) to 0xB8
 *  Write 0x0000 to memory (11 * 16 + 8 == ODR Gyro Calibr)
 *  Set register 0x7E (Memory Bank Select) to 0x01
 *  Set register 0x7C (Memory Start Address) to 0x30
 *  Write 0x7FFFFFFF to memory (19 * 16 + 0 == Gyro Scaling Factor)
 *  Set register 0x07 (Power Management 2) to 0x78
 *  Set register 0x7E (Memory Bank Select) to 0x00
 *  Set register 0x7C (Memory Start Address) to 0x8A
 *  Write 0x0001 to memory (8 * 16 + 10 == Data Ready Status)
 *  .....
 *  Set register 0x7C (Memory Start Address) to 0x40
 *  Write 0xC048 to memory (4 * 16 + 0 == Data Out Control 1)
 *  Set register 0x7C (Memory Start Address) to 0x4C
 *  Write 0xC048 to memory (4 * 16 + 12 == Data Interrupt Control)
 *  Set register 0x7C (Memory Start Address) to 0x42
 *  Write 0x6000 to memory (4 * 16 + 2 == Data Out Control 2)
 *  Set register 0x7C (Memory Start Address) to 0x4E
 *  Write 0x0300 to memory (4 * 16 + 14 == FIFO Watermark)
 *  Set register 0x7E (Memory Bank Select) to 0x01
 *  Set register 0x7C (Memory Start Address) to 0x0C
 *  Write 0x00E8BA2E to memory (16 * 16 + 12 == Accel Only Gain)
 *  Set register 0x7E (Memory Bank Select) to 0x05
 *  Set register 0x7C (Memory Start Address) to 0xB0
 *  Write 0x06666666 to memory (91 * 16 + 0 == Accel Alpha Var)
 *  Set register 0x7C (Memory Start Address) to 0xC0
 *  Write 0x39999A to memory (92 * 16 + 0 == Accel A Var)
 *  Set register 0x7C (Memory Start Address) to 0xE4
 *  Write 0x0000 to memory (94 * 16 + 4 == Accel Cal Rate)
 *  .....
 *  Set register 0x7F (Register Bank Select) to 0x20 == Bank 2
 *  Set register 0x10 (Accel Sample Rate Divider 1&2) to 0x00E0
 *  .....
 *  Set register 0x7F (Register Bank Select) to 0x00 == Bank 0
 *  Set register 0x7E (Memory Bank Select) to 0x00
 *  Set register 0x7C (Memory Start Address) to 0xBE
 *  Write 0x0000 to memory (11 * 16 + 14 == ODR Accel)
 *  Set register 0x7C (Memory Start Address) to 0xBA
 *  Write 0x0000 to memory (11 * 16 + 10 == ODR Gyro)
 *  Set register 0x7C (Memory Start Address) to 0xB8
 *  Write 0x0000 to memory (11 * 16 + 8 == ODR Gyro Calibr)
 *  Set register 0x07 (Power Management 2) to 0x40
 *  Set register 0x7C (Memory Start Address) to 0x8A
 *  Write 0x0003 to memory (8 * 16 + 10 == Data Ready Status)
 *  .....
 *  Set register 0x7C (Memory Start Address) to 0x40
 *  Write 0xC848 to memory (4 * 16 + 0 == Data Out Control 1)
 *  Set register 0x7C (Memory Start Address) to 0x4C
 *  Write 0xC848 to memory (4 * 16 + 12 == Data Interrupt Control)
 *  Set register 0x7C (Memory Start Address) to 0x42
 *  Write 0x6000 to memory (4 * 16 + 2 == Data Out Control 2)
 *  Set register 0x7C (Memory Start Address) to 0x4E
 *  Write 0x0300 to memory (4 * 16 + 14 == FIFO Watermark)
 *  Set register 0x7C (Memory Start Address) to 0xBE
 *  Write 0x0000 to memory (11 * 16 + 14 == ODR Accel)
 *  Set register 0x7C (Memory Start Address) to 0xBA
 *  Write 0x0000 to memory (11 * 16 + 10 == ODR Gyro)
 *  Set register 0x7C (Memory Start Address) to 0xB8
 *  Write 0x0000 to memory (11 * 16 + 8 == ODR Gyro Calibr)
 *  Set register 0x07 (Power Management 2) to 0x40
 *  Set register 0x7C (Memory Start Address) to 0x8A
 *  Write 0x0003 to memory (8 * 16 + 10 == Data Ready Status)
 *  .....
 *  Set register 0x7C (Memory Start Address) to 0x40
 *  Write 0xC848 to memory (4 * 16 + 0 == Data Out Control 1)
 *  Set register 0x7C (Memory Start Address) to 0x4C
 *  Write 0xC848 to memory (4 * 16 + 12 == Data Interrupt Control)
 *  Set register 0x7C (Memory Start Address) to 0x42
 *  Write 0x6000 to memory (4 * 16 + 2 == Data Out Control 2)
 *  Set register 0x7C (Memory Start Address) to 0x4E
 *  Write 0x0300 to memory (4 * 16 + 14 == FIFO Watermark)
 *  Set register 0x7C (Memory Start Address) to 0xBE
 *  Write 0x0000 to memory (11 * 16 + 14 == ODR Accel)
 *  Set register 0x7C (Memory Start Address) to 0xBA
 *  Write 0x0000 to memory (11 * 16 + 10 == ODR Gyro)
 *  Set register 0x7C (Memory Start Address) to 0xB8
 *  Write 0x0000 to memory (11 * 16 + 8 == ODR Gyro Calibr)
 *  Set register 0x07 (Power Management 2) to 0x40
 *  Set register 0x7C (Memory Start Address) to 0x8A
 *  Write 0x0003 to memory (8 * 16 + 10 == Data Ready Status)
 *  Set register 0x06 (Power Management 1) to 0x21
 *  Select and read register 0x19 (Interrupt Status)
 *  ICM returns 0x0A
 *  Select and read register 0x18 (DMP Interrupt Status)
 *  ICM returns 0x01
 *  Select and read register 0x70 (FIFO Count Hi&Lo)
 *  ICM returns 0x0000
 *  Select and read register 0x19 (Interrupt Status)
 *  ICM returns 0x00
 *  Select and read register 0x18 (DMP Interrupt Status)
 *  ICM returns 0x00
 *  Select and read register 0x70 (FIFO Count Hi&Lo)
 *  ICM returns 0x0000
 *  .....
 *  .....
 *  Select and read register 0x19 (Interrupt Status)
 *  ICM returns 0x04
 *  Select and read register 0x18 (DMP Interrupt Status)
 *  ICM returns 0x00
 *  Select and read register 0x70 (FIFO Count Hi&Lo)
 *  ICM returns 0x0000
 *  Select and read register 0x19 (Interrupt Status)
 *  ICM returns 0x00
 *  Select and read register 0x18 (DMP Interrupt Status)
 *  ICM returns 0x00
 *  Select and read register 0x70 (FIFO Count Hi&Lo)
 *  ICM returns 0x0000
 *  .....
 *  .....
 *  Select and read register 0x19 (Interrupt Status)
 *  ICM returns 0x00
 *  Select and read register 0x18 (DMP Interrupt Status)
 *  ICM returns 0x00
 *  Select and read register 0x70 (FIFO Count Hi&Lo)
 *  ICM returns 0x001C
 *  Select and read register 0x72 (FIFO Read Write)
 *  Data Stream is: 
 *  Header:  0xC048 : Accel & Gyro & Gyro_Calibr & Header2
 *  Header2: 0x6000 : Accel_Accuracy & Gyro_Accuracy
 *  Accel:   0x0130 0xFD3C 0x1FD0
 *  Gyro:    0xFFE7 0x000C 0x0007
 *  Gyro_Bias:      0x0000 0x0000 0x0000
 *  Accel_Accuracy: 0x0000
 *  Gyro_Accuracy:  0x0000
 *  Footer:  0x20DD
 *  .....
 *  Header:  0xC040 : Accel & Gyro & Gyro_Calibr
 *  Accel:   0x0178 0xFD84 0x1F44
 *  Gyro:    0xFFEE 0x0016 0x0000
 *  Gyro_Bias:      0x0000 0x0000 0x0000
 *  Footer:  0x70DD
 *  .....
 *  Header:  0xC040 : Accel & Gyro & Gyro_Calibr
 *  Accel:   0x0134 0xFDAC 0x1FC4
 *  Gyro:    0xFFF9 0x0013 0x0001
 *  Gyro_Bias:      0x0000 0x0000 0x0000
 *  Footer:  0x70DD
 *  .....
 *  Select and read register 0x19 (Interrupt Status)
 *  ICM returns 0x02
 *  Select and read register 0x18 (DMP Interrupt Status)
 *  ICM returns 0x01
 *  Select and read register 0x70 (FIFO Count Hi&Lo)
 *  ICM returns 0x0022
 *  Select and read register 0x72 (FIFO Read Write)
 *  Data Stream is: 
 *  Header:  0xC840 : Accel & Gyro & Quat6 & Gyro_Calibr
 *  Accel:   0x0188 0xFDC4 0x1FA4
 *  Gyro:    0xFFF1 0x0019 0xFFFF
 *  Gyro_Bias:      0x0000 0x0000 0x0000
 *  Quat6:   0xFFC7A057 0x0030BD92 0x000A6646
 *  Footer:  0x00DB
*/

The raw I2C data is in the attached file:

ericalbers1.txt

[n2d7]

Hi Paul,
Really appreciate you looking in to this. Sadly, I don't have much experience at low level code :/ (I am a student). But I will try to see how the above differs from the current code.

[PaulZC]

Hi @n2d7 ,
Success!
I've made improvements to the DMP configuration and "read FIFO" code.
The critical thing (which I had missed) is that the Data Ready Status register needs to be set when requesting accelerometer and/or gyro values from the DMP. Oddly, it doesn't need to be set when requesting only quaternions...
I've added a new example which - I think - does exactly what you need. Please give it a try and let me know what you find.
You will need to download the complete library, not just the new example.
And please don't forget to edit ICM_20948_C.h and uncomment line 29, otherwise the DMP won't work.
Best wishes,
Paul

[PaulZC]

Resolved in Version 1.2.0
Closing...

[n2d7]

Hi Paul,
I started checking the code with Example6_DMP_Quat9_Orientation. I checked with 3 IMUs connected with SPI (one at a time). While I receive the incoming quaternion values, I think they are wrong. For 2 IMUs I checked, when I visualized the values, 90 degree turn of the real IMU was visualized as 2 full turns. Additionally it was not the visualization was not flat it was supposed to (I have used the same visualization setup before). For the other one, q1,q2,q3 values were either increasing or decreasing constantly). So I think their may be a something missing when configuring the quaternion values.

Similarly, for Example7_DMP_Quat6_EulerAngles.inoyaw, pitch, roll values were constantly increasing or decreasing for all 3 IMUs.

Initialization of the sensor returned: All is well.
Device connected!
DMP enabled!
Roll:0.0 Pitch:0.1 Yaw:0.3
Roll:0.0 Pitch:0.2 Yaw:0.6
Roll:0.1 Pitch:0.4 Yaw:0.9
Roll:0.1 Pitch:0.5 Yaw:1.1
Roll:0.2 Pitch:0.6 Yaw:1.4
Roll:0.2 Pitch:0.7 Yaw:1.7
Roll:0.2 Pitch:0.8 Yaw:2.0
Roll:0.2 Pitch:0.9 Yaw:2.3
Roll:0.3 Pitch:1.0 Yaw:2.6
Roll:0.3 Pitch:1.1 Yaw:2.8
Roll:0.3 Pitch:1.2 Yaw:3.1
Roll:0.4 Pitch:1.3 Yaw:3.4
Roll:0.4 Pitch:1.4 Yaw:3.7
Roll:0.4 Pitch:1.4 Yaw:4.0
Roll:0.5 Pitch:1.5 Yaw:4.2
Roll:0.5 Pitch:1.6 Yaw:4.5
Roll:0.5 Pitch:1.7 Yaw:4.8
Roll:0.5 Pitch:1.7 Yaw:5.0
Roll:0.5 Pitch:1.8 Yaw:5.3
Roll:0.5 Pitch:1.8 Yaw:5.6
Roll:0.5 Pitch:1.9 Yaw:5.8
Roll:0.6 Pitch:2.0 Yaw:6.1
Roll:0.6 Pitch:2.0 Yaw:6.4
Roll:0.6 Pitch:2.1 Yaw:6.7
Roll:0.6 Pitch:2.1 Yaw:6.9
Roll:0.6 Pitch:2.2 Yaw:7.2
Roll:0.6 Pitch:2.3 Yaw:7.5
Roll:0.7 Pitch:2.3 Yaw:7.8
Roll:0.7 Pitch:2.3 Yaw:8.0
Roll:0.7 Pitch:2.4 Yaw:8.3
Roll:0.7 Pitch:2.4 Yaw:8.6
Roll:0.7 Pitch:2.4 Yaw:8.9
Roll:0.7 Pitch:2.5 Yaw:9.1
Roll:0.7 Pitch:2.5 Yaw:9.4
Roll:0.7 Pitch:2.6 Yaw:9.7
Roll:0.8 Pitch:2.6 Yaw:9.9
Roll:0.8 Pitch:2.6 Yaw:10.2
Roll:0.8 Pitch:2.6 Yaw:10.5
Roll:0.8 Pitch:2.6 Yaw:10.8
Roll:0.8 Pitch:2.7 Yaw:11.1
Roll:0.8 Pitch:2.7 Yaw:11.4
Roll:0.8 Pitch:2.7 Yaw:11.6
Roll:0.9 Pitch:2.7 Yaw:11.9
Roll:0.9 Pitch:2.8 Yaw:12.2
Roll:0.9 Pitch:2.8 Yaw:12.4
Roll:0.9 Pitch:2.8 Yaw:12.7
Roll:0.9 Pitch:2.8 Yaw:12.9

I also check with the Example8_DMP_RawAccel.ino. For all 3 IMUs, I did a plot of the acceleration values and tested them with simple movements. Their values seems to be accurate (by dividing the values by 2^16, it shows closed to 1g in the correct direction, also I plotted the values and moved the IMUs and checked if the movement matched the plot)

[PaulZC]

Hi @n2d7,
Can you please check that you have installed version 1.2.0 of the library? There was a mistake in the earlier code that meant the magnetometer was not being configured correctly. I was seeing the same "2 full turn" behavior before I corrected the code.
Also, can you try turning the sensor through a complete revolution in all three axes - to allow the DMP to calibrate.
Please let me know what you find.
Best wishes,
Paul

[PaulZC]

Hi @n2d7 ,
OK. I see the same behavior with the Quat9 example - a slow drift in Q3. The Quat6 data (Example7) seems much better behaved.
InvenSense did give me some advice:
"I would start with the Quat6 first and see if you are seeing this drift. The reason is that Quat9 integrate the mag and until the mag data is calibrated it could cause probably this strange yaw movements. With the Quat6 you will only get the quaternions from the accel and gyro which would be more stable.
You might see a drift due to the initial offsets. But the drift should be smaller and less erratic. Then after the DMP calibrates the gyro it should be much more stable."
So, I suspect this is a calibration issue.
I will investigate further!
Best wishes,
Paul

[PaulZC]

Hi @n2d7 ,
I've made some improvements to the way the DMP is configured in Version 1.2.1.
Please give the updated examples a try. I still see drift on the Quat9 Q3 initially, but after rolling the sensor around all three axes, it seems to stabilize OK.
Best wishes,
Paul