DRV10987EVM: I2C lines always low out of the box

Christoph Schweiker

Part Number: DRV10987EVM
Other Parts Discussed in Thread: USB2ANY, DRV10983, DRV10987

Tool/software:

Hello,

I have a DRV10987EVM to gather the right parameters to drive a motor. I can setup the GUI but cannot establish communication with the USB2Any device. The device looks fine. But on the EMV-Board, the clock and data lines are always held low. Even with no connector and the bare board (powered via external 24V), both lines are always low. The 5V, 3V3 and 1V8 are there and stable, and there are the standard pull up resistors on the board with 3V3 on the high side and ~0V on the SDA / SCL side. Is the chip just broken? It is a stand-by chip (DRV10987S) so the I2C communication should be active regardless of the speed pin. Enabling the speed pin via the trimmer on the board does not change the problem. Any ideas?

Best regards

Christoph

11 months ago

0 Sachin S 11 months ago

TI__Expert 6011 points

Hi Christoph,

The EVM is expected to work out of the box. Could you please check this EVM user guide if you haven't already, and make sure we are not missing anything.

Thanks and regards,

Sachin S

0 Christoph Schweiker 11 months ago in reply to Sachin S

Prodigy 10 points

When I open the GUI I get the error message "DRV10983.USB2ANY.lvclass: Write Register.vi<ERR> Register writing not successful!! Please restart the GUI and restart again. The error occurs with or without connection to the EVM board.

While troubleshooting this error I tried to look at the I2C lines if there is any signal at all. During that I encountered the problem that the lines are always low, even when the connector from EVM to USB2ANY is not connected. Power signals are there, pull-ups are there, but the DRV10987 pulls both lines low it seems.

0 Sachin S 11 months ago in reply to Christoph Schweiker

TI__Expert 6011 points

Hi Christoph,

I just checked at my end if this is expected, SCL line should be pulled up.

Could you confirm if the USB2ANY is connected to the EVM when you measured the voltages on I2C.

Thanks and regards,
Sachin S

0 Christoph Schweiker 11 months ago in reply to Sachin S

Prodigy 10 points

Hello Sachin,

The voltages on I2C are always low, whether the USB2Any is connected or not. In both cases there is VReg = 5V, 3V3 and 1V8 are there, but the I2C lines are low. The USB2ANY is found within the DRV109xx-EVM GUI and the USB2ANY Explorer. Trying to manually send an I2C packet via the Explorer always ends in a write timeout with no activity on any of the two I2C lines.

Best regards

Christoph S

0 Sachin S 11 months ago in reply to Christoph Schweiker

TI__Expert 6011 points

Hi Christoph,

Is it possible for you to remove these pull up resistors? And check the impedance on the I2C pins to GND?

We can compare to the expected values and infer if the device is healthy.

Thanks,

Sachin S

0 Christoph Schweiker 11 months ago in reply to Sachin S

Prodigy 10 points

Hello Sachin,

the impedance of the I2C lines to GND is for the clock 77.8 Ohms and for Data 10.4 Ohms. No significant changes after removing all three pull-up resistors. The resistors were 4.75kOhm. Still all lines low with or without connection to USB2ANY device when powered on.

Best regards

Christoph

0 Sachin S 11 months ago in reply to Christoph Schweiker

TI__Expert 6011 points

Hi Christoph,

Thanks for the measurements, let me check with the good device at my end on these impedances.

Regards,

Sachin S

0 Christoph Schweiker 11 months ago in reply to Sachin S

Prodigy 10 points

Hello Sachin,

are there any updates?

Best regards

+1 Sachin S 10 months ago in reply to Christoph Schweiker

TI__Expert 6011 points

Hello Christoph,

Apologies for the late response. I checked the impedances at my end, I am seeing 1Mohm on SCL and open on SDA.

Looks like the unit you have may be damaged.

Thanks and regards,

Sachin S

0 Christoph Schweiker 10 months ago

Prodigy 10 points

Just a quick follow-up, I received a replacement unit and everything works right out of the box.

0 Sachin S 10 months ago in reply to Christoph Schweiker

TI__Expert 6011 points

Great to know!

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DRV10987EVM: I2C lines always low out of the box