FS6500 Request FSxB Low Driver Function not working

[ndasanay]

Hi,

I'm trying to use the Driver code to request FSxB low, specifically FS0B. Per the FS6500 documentation, a SPI Command can be used to request FS0B low. However, when I try to use the driver code, which simply writes to SF_OUTPUT_REQUEST secured register with the FS0B_REQ bit set, nothing seems to happen. I'm able to release FSxB at the end of initialization successfully, but FSxB stays high.

Is this simply due to no faults occurring in the system, so the output won't assert?

Thanks.

[diazmarin09 · Accepted solution]

Hello Ndasanay,

I hope this response finds you well.

You are correct, these pins are asserted low by the device during a failure. The FS0B and FS1B are active low output pins. These pins are usually connected to a safety switch.

In this case, I assume you are referring to the FS0B safety path check.

Please make sure you are asserting the FS0B_REQ bit from the SF_OUTPUT_REQ register. A write command must be sent by the MCU.

Could you please verify that the driver is sending the correct SPI writing command to the device?

Regards,

David

[ndasanay]

Hi,

Thank you for the quick response! You are correct in everything you say. I figured out the problem on my end. I realize my watchdog refresh function attempts to release the FSxB pins each refresh. Since error counter is 0 when I request FS0B low, the refresh releases the pin very quickly so I didn't notice it until I put a logic analyzer on the pin.

Thank you again!

Best