GD3100 - WDOG Fault

[Dan_Krause]

What are potential root causes for continuous WDOG_FAULT after every SPI message.

Configuration is 6 devices in daisy chain. WDG_FLT flag set and INTb is set after each SPI message on all devices. But SPI communication is working without issues. 

I understood temporary loss of VDD could be a root cause. Any other potential known issues?

What could customer check in addition?

[travisalexander]

Hi Daniel,

Sure, in long daisy-chain configurations WDOG can be more likely if the configuration is not set correctly.

What is the watchdog timeout setting, and what is the total time for a message? If this is shorter than the message length itself (varies by # of devices in the daisy-chain, clock frequency, time between frames, etc.) this will cause a WDOG fault, even though the SPI communication is valid.

These problems are not exclusive to 6-device daisy chains (nor is it prohibitive) but the problems are compounded with long chains, many devices, etc.

No COMERR or SPIERR at the same time either, only WDOG?

Regards,

Travis

[travisalexander]

Resolution: SPI frame was too long, causing WDOG faults (no SPIERR or COMERR) during normal message transition. Shortening the SPI frame (reducing dead time in between device frames, etc.) can reduce the total daisy chain message length below 2ms, the maximum watchdog timeout setting.

See attached email for customer (Audi) resolution confirmed.

Travis