ESP32-P4 D+ D- line (IDFGH-16852)

[Maxim88S]

Answers checklist.

• I have read the documentation ESP-IDF Programming Guide and the issue is not addressed there.
• I have updated my IDF branch (master or release) to the latest version and checked that the issue is present there.
• I have searched the issue tracker for a similar issue and not found a similar issue.

General issue report

I'm currently in the process of designing a PCB for my board with an ESP32-P4.

I have a question – can I program the ESP via the D+ and D- lines, for example, by redirecting the JTAG to these lines? This would be to avoid using extra pins.

Another question – I read here (https://github.com/espressif/esp-idf/tree/master/examples/peripherals/usb#usb-phy-pin-mapping) that the pin assignments for D+ and D- have changed depending on the board version.

How can I determine which version of the chip I have, and have the positions of any other pins changed?

[ginkgm]

Hi @Maxim88S ,

You can refer to our documentation site: https://documentation.espressif.com/en/home to find this kind of information.

Click P4 > SoC > ESP32-P4 Series SoC Errata

[ginkgm]

From software side, You can run esptool chip-id to get it via esptool

[ginkgm]

To download, you need to use the USB-serial-JTAG port instead of USB OTG port.

There is a way to swap, though not documented: usb_serial_jtag_ll_phy_enable_pin_exchg

But it will be less convenient:

• Please connect the USB port to default pins of USJ (called THE PINS below)
• By default (On reset), USJ is connected. After power up, your program use the register above to swap the PHY so that USB-OTG v1.1 is connected to the pins.
• Now you are not able to auto-program anymore. When you want to download, you need to stop your programming from running by resetting your chip into the download mode (using EN and strapping). And then the USJ will be connected and you will be able to download again. After download, USJ will not be able to reboot the chip. You will need to manually reset the chip into the SPI boot mode.
• Btw, USJ port may also be your console. So you will not be able to see console output if USJ is not connected to the pins after the swap.

So I still suggest if you want to develop USB, prepare a USB port for the console, either USJ or the USB-uart converter via UART pins.