ESP32 Forum

Posted: **Sat Apr 18, 2026 8:08 am**

Good afternoon. I don’t understand how USB works on this platform. The chip revision is 1.3. When I hold the BOOT button and connect USB, I see a JTAG controller and a COM port. I cannot flash firmware via JTAG — it shows:

Code: Select all

Info : esp_usb_jtag: VID set to 0x303a and PID to 0x
1001
Info : esp_usb_jtag: capabilities descriptor set to 0x2000

Info : Listening on port 6666 for tcl connections

Info : Listening on port 4444 for telnet connections

❌ Error: esp_usb_jtag: could not find or open device!

Error: esp_usb_jtag: could not find or open device!

❌ 
Error: [esp32p4.hp.cpu0] Unsupported DTM version: -1
Error: [esp32p4.hp.cpu0] Could not identify target type.
Error: [esp32p4.hp.cpu1] Unsupported DTM version: -1
Error: [esp32p4.hp.cpu1] Could not identify target type.

I can flash firmware via the COM port, and it runs — I even managed to bring up a MIPI DSI display. However, no matter what I do, in normal (non-BOOT) mode neither JTAG nor the COM port appears in the device list. There is not even a sound indicating that a new device has been connected.

Posted: **Tue May 12, 2026 11:43 am**

Hello,

I know that v1.3 is NRND but I have no other choice now, I already got the modules.

I'm having exactly the same issue which is "fixed" by connecting both USBs at gpio 24/25 and 26/27 but that is not solution to the issue. But when only 24/25 are connected there are issues. In non-boot mode there is no usb enumeration at all, and in boot mode it enumerates on usb as ttyACM0 but as soon as i try to use it it reenumerates as new ttyACM1. Sometimes I can get it to flash via usb-serial in boot mode but jtag does not work at all.

Did you find a fix to your issue?

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