2022-07-08 10:59 AM
I have a PD-Source project using the STM32G0B1RC component. It is serving as a power source.
Referring to page 43, Figure 24 of UM2552, my application makes it to a successful call of "USBPD_PE_SRC_EvaluateRequest". The port partners' requested PDO is accepted. The "ACCEPT" goes out over the wire to the partner and the partner returns a GoodCRC packet. I have this captured with a protocol sniffer from Cypress.
According to the state diagram on page 43, there is supposed to be a call to DPM_Notify to let the application know the request was accepted. There is then supposed to be another notification about a power state change and then a call to set up the approved power supply.
This never happens. Instead, the port partner sends three cable resets. This IS reported by DPM_Notify but then the stack stops.
What would cause the stack state machine to behave this way?