[SOLVED] Fresh (empty?) WROOM32 and cannot connect using JTAG

[tobias.boesch]

I try to program a WROOM32 on a custom PCB and I get JTAG chain errors:

Code: Select all

Open On-Chip Debugger  v0.10.0-esp32-20200709 (2020-07-09-08:54)
Licensed under GNU GPL v2
For bug reports, read
	http://openocd.org/doc/doxygen/bugs.html
Info: esp-huzzah-32.cfg is not an official configuration file.
Info : Configured 2 cores
Error: libusb_open() failed with LIBUSB_ERROR_NOT_SUPPORTED
Info : clock speed 500 kHz
Error: JTAG scan chain interrogation failed: all zeroes
Error: Check JTAG interface, timings, target power, etc.
Error: Trying to use configured scan chain anyway...
Error: esp32.cpu0: IR capture error; saw 0x00 not 0x01
Warn : Bypassing JTAG setup events due to errors
Info : Listening on port 3333 for gdb connections
Error: JTAG scan chain interrogation failed: all zeroes
Error: Check JTAG interface, timings, target power, etc.
Error: Trying to use configured scan chain anyway...
Error: esp32.cpu0: IR capture error; saw 0x00 not 0x01
Warn : Bypassing JTAG setup events due to errors
Error: esp32_soc_reset: Couldn't halt target before SoC reset
** Unable to reset target **
shutdown command invoked

This error was solved multiple times on this and other forums by fixing hardware issues. I mesaured the JTAG signals and the TDO signal is always zero. The other JTAG signals look good.
The TDO pin has the same hardware configuration as a HUZZAH32 board. (The HUZZAH32 board can be flashed using this JTAG device configuration. So there shouldn't be an OpenOCD configuration issue)

The WROOM32 module is fresh and might not have any software flashed. Is it possible to flash such a module using JTAG? Could a missing firmware lead to a not responding TDO pin?

[tobias.boesch]

Very likely this is the solution:

https://docs.espressif.com/projects/esp ... lity-issue

[tobias.boesch]

I can confirm, replacing the AT firmware using UART flash makes JTAG work.