Getting info for the source capabilities

[thetiana]

Hello,

Is it possible to read the information about the source capability and how to send it to UART?

I am working around project to power my old laptop with USB-PD.
My idea is to use part of debug to read info about selected PD profile and mainly how much W can draw from the source. with the second MCU i will simulate DS2505 which is a communication chip inside the charger containing info about power capability of the charger. with this configuration i never harm the PD charger.

I look the debug code, but i cant find any code providing data how much amperes A can provide the charger, i think the voltage can be easily read and send to UART, when V and A are available the W can be calculated and sent to UART

[manuelbl]

This can be achieved with more or less the following steps:

• Ensure debug output is not activated (by not defining the PD_DEBUG macro)
• Change the code in pd_debug.cpp such that the UART code is always included
• Modify on_source_caps_changed so it writes the desired information to UART using uart_transmit or uart_print. The information is available on the power_sink object, in particular in the source_caps array.

Note that on_source_caps_changed must immediately select a voltage. Otherwise it is likely that you run into a timeout of the USB PD charger and it will reset. Just select 5V (power_sink.request_power(5000);) until your second MCU has decided for another voltage.

If the ZYPDN12 is also supposed to receive commands via UART, you will have to extend the UART code in pd_debug.cpp.

UART TX is on pin PA2, UART RX is on pin PA3.

[noahwilliamsson]

If the ZYPDN12 is also supposed to receive commands via UART, you will have to extend the UART code in pd_debug.cpp.
UART TX is on pin PA2, UART RX is on pin PA3.

FWIW, the first commit on my apple-vdm branch enables both RX and TX and adds a stub for an UART debug loop.

Here's a STM32F030F4 quickref with pinouts. I soldered a pair of enamel wires onto PA2 and PA3 after removing the screw terminal on my board.

@manuelbl btw, really nice work on putting this OSS firmware (along with the detailed docs) together!

[manuelbl]

Thanks for the update on your project. Looks very promising.