DRV10987: I2C write with no ACK at last byte

Mateus Pereira62

Part Number: DRV10987
Other Parts Discussed in Thread: USB2ANY

Dear guys,

I am currently trying to control a BLDC motor using the DRV10987S and TM4C123G (but also tried with arduino - same issues). First, the main problem is that the device does not ACK the last byte for any 2-byte write via I2C. Using oscilloscope I could figure out this strange behaviour.

The picture below shows a communication write to register 0x30 (SpeedCtrl) with value 0x800A (I2C Override and Speed = 10). In the communication you can identify it as LITTLE ENDIAN, but I also tried with BIG ENDIAN as there is no info about it on datasheet: www.ti.com/.../drv10987.pdf section 8.5 Page 47.

The communication is: Start, Addr=0x52, R/W=0, ACK, Reg=0x30, ACK, Data=0x0A, ACK, Data=0x80, NACK, Stop

There is no ACK from device after 2nd byte, although the ACK is seen for any other transfer. This happens with every 2-byte write operation.

Besides this problem, the device ID read is always 0x00FF, confirmed by oscilloscope measurements. Also, the first read to FaultReg returns 0x00FF, and after writing 0xFFFF (or 0xFF ?) to clear register, every other read returns 0xFFFF.

So, simplyfing:

[1] No ACK after 2nd byte during I2C write;

[2] Device ID 0x00FF and Status 0xFFFF;

[3] I2C hardware from TM4C123G may not be the problem, as it works with other sensors at the bus.

Thanks for any kind of help,

Mateus

over 5 years ago

0 Brian Schmidt over 5 years ago

TI__Intellectual 2600 points

Mateus,

It looks like your data packet is backward when you write to register 0x30. It should be 0x80 then 0x0A (MSB then LSB).

I'll capture the same sequence on our EVM and send it.

Thanks,
Brian

0 Mateus Pereira62 over 5 years ago in reply to Brian Schmidt

Prodigy 40 points

Hi Brian, thanks for your time.

Yes, I know the packet in that picture is backwards. There is no info about endianess at datasheet, so I tried both ways. No matter if I send MSB first or LSB first, the device does not ACK the last byte and because of this no further communications is performed. I can't set any config or read any data.

My next step is to assemble another board using 2nd of 3 parts available.

There is another strange behaviour. As soon as I set power on, the motor starts a pattern of vibrating, 2 turns and stop; repeatedly within +-10 sec. I'm not sure if its a deffective part or this happened because I did not config the device.

Thanks,

Mateus

0 Brian Schmidt over 5 years ago in reply to Mateus Pereira62

TI__Intellectual 2600 points

Mateus,

When I use our EVM and USB2ANY I don't see any missing ACKs or NAKs. Please see the attached files one for read and one for write.

Thanks,

Brian

DRV10987 Write.pdf DRV10987 Read.pdf

8233.DRV10987 Write.pdf

0 Brian Schmidt over 5 years ago in reply to Brian Schmidt

TI__Intellectual 2600 points

Mateus,

Any follow up questions?

Thanks,
Brian

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DRV10987: I2C write with no ACK at last byte