Non-EPR hardware protection

dojoe commented 1 year ago

Detect EPR voltages on Twinkie and Twonkie v1 hardware, force the source to turn off to protect the voltage monitor chips.

Options:

Sniff PD negotiation and detect EPR voltages being negotiated; inject control channel states that will abort the negotiation if so.
- Pro: Prevents dangerous voltages completely
- Con: Hard to implement, firmware might miss packets and thus not trigger
Set INA up to alert above 24V, immediately react in the interrupt handler by forcing the control channels into an invalid/reset state (possible?)
- Pro: Easier implementation
- Con: May be too late to protect the chips 💥

dojoe commented 1 year ago

Prerequisite: EPR capable source and sink for testing

FCALLBOX commented 6 months ago

hi Dojoe, I am a little bit confused about the USB-C work when the the source are asking for 9V or 15V or 20V, the V2 HW cannot support such voltages as there is a zener 5V6 on VBUS and that the LDO MC5504 can only work at 5.5V max.

FCALLBOX commented 6 months ago

So If I understand you does not allow USB-C negotiation over 5V ?

dojoe commented 6 months ago

Hey @FCALLBOX! The diode and vreg are on the analyzer logic supply which is always 5V, provided via the Micro-B receptacle by the controlling PC. The USB-C voltages are only observed via the INAxxx chips, they don't power anything on the board. Does this help?

dojoe / Twonkie

Non-EPR hardware protection #8