DRV8718-Q1: OT_WD_AGD

Hey Colt,

Colt Zhang said:

when CS is pulled high, the MCU sends the initialization instructions through SPI. However, there is no response from the DRV8718.

They need to follow the SPI data format and timing diagrams specified in the datasheet.  nSCS should be LOW when writing/reading to the device. 

Best,

Jacob

Hi

   When the MCU sends the initialization instructions through SPI, the CS is pulled low. After that，the CS is set to high.

    We found that when the DRV8718 was waked up , the MCU sends the initialization instructions through SPI with the SPI data format. However, there is no response from the DRV8718.

hi Jacob,

below is summary about customer's reply and question.

1  When the MCU sends the initialization instructions through SPI, the CS is pulled low. After that，the CS is set to high.

    they found that when the DRV8718 was waked up , the MCU sends the initialization instructions through SPI with the SPI data format. However, there is no response from the DRV8718.

2 Customer wants to know if there is a requirement for the order of the 8718 wake up? What actions are required, including the interval between each action? Operations include Nsleep raise, SPI enable, 8718 initialization, fault clearing (which faults need to be cleared), and more 

Hi Jacob，

Any progress of this problem?

Hi Colt, Zhuo,

Is the t_wakeup spec being met:

After nSLEEP going high wait 1 ms and then start sending the SPI commands. Does this happen on an EVM, or on their own board?

Has this occurred on multiple boards?

Here is the EVM software for reference:

DRV8718S-Q1EVM Evaluation board | TI.com

Best,

Keerthi

Hi ,

Thank you for your reply. We'll check out the reference .

We set Nsleep to high. Then wait for some time to send the SPI commands. The time is 0ms, 10ms or 20ms.

This problem happens on our own board.

In addition, under what circumstances will an AGD fault be reported？Please help with an example。

 Thanks!

Hi Zhuo,

Can you share a schematic of your board?

Here is the register map description:

Are you using any AGD features? 

Best,

Keerthi

Hi Zhuo,

Any updates on this.

Best,

Keerthi

Hi Keerthi;

The schematic diagram is attached. We don't use AGD-related registers, they're all defaults.

Monitor SPI communication data. It was found that when 8718 woke up, the data sent, 8718 did not reply.

After waking up, there are about 10 frames, and after that, can reply normally

Above, please confirm. Thank you！

Hi Zhuo,

Let me review this and give you an update tomorrow.

Best,

Keerthi

Hey Zhuo,

Just to check, have you confirmed this behavior occurs on multiple DRV8718-Q1 devices and multiple copies of your board?

Your 0ms/10ms/20ms wait times are all within the Watchdog time frame, so shouldn't be watchdog triggering the OT_WD_AGD fault, but it might be worth reading that register to confirm.  

Best,

Jacob