ESP32-DEVKITC and ESP-PROG

keebler411
Posts: 2
Joined: Sun May 02, 2021 9:12 pm

ESP32-DEVKITC and ESP-PROG

Postby keebler411 » Sun May 02, 2021 10:12 pm

I am not able to program the ESP32 with the ESP-PROG using the Arduino IDE. I can program the board using the built-in serial port on the dev kit. So its probable the settings other than com port do not need to be changed. If I connect the ESP-PROG to the dev kit, open the programming serial port, and press/release both RST/BOOT programming mode is entered manually:

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rst:0x1 (POWERON_RESET),boot:0x3 (DOWNLOAD_BOOT(UART0/UART1/SDIO_REI_REO_V2))

waiting for download
So why does the automatic download not work? Using the upload function in the Arduino IDE results in a timeout. I've selected ESP32 Dev Module as the board. Solving this is a necessary step to incorporating the actual module on a custom PCB.

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esptool.py v2.6
Serial port COM6
Connecting........_____....._____....._____....._____....._____....._____....._____

A fatal error occurred: Failed to connect to ESP32: Timed out waiting for packet header
A fatal error occurred: Failed to connect to ESP32: Timed out waiting for packet header
The strapping pins themselves seem to be fairly well documented, but there still seems like a step is missing. Can anyone from Espressif PLEASE write an app note about this?

keebler411
Posts: 2
Joined: Sun May 02, 2021 9:12 pm

Re: ESP32-DEVKITC and ESP-PROG

Postby keebler411 » Tue May 04, 2021 9:30 pm

So I accidentally found out what the problem is. I also have a header connected to Serial0 for a TTL serial adapter. I programmed a loopback on Serial0 and it works using the onboard serial connection BUT NOT the TTL serial adapter. I can send data out from the ESP32 (ie TXD0 works) but the RXD0 does not. RXD0 is connected to the CP102 chip:

https://dl.espressif.com/dl/schematics/ ... 80607a.pdf

Coincidentally this is a similar problem I had when connecting an ESP8266 to an ATMEGA2560 on its bootloader port. I couldn't bootload the ATMEGA from a TTL adapter unless I cut the Tx-->Rx connection from the ESP8266.

Espressif PLEASE document that the ESP-PROG will not program the devkits over serial. Future revisions should include a jumper for RXD0. This kind of prototyping is absolutely critical to allow someone to create a surface mount board using the bare modules. Thank you.

Okay, I can see now that this is [one of] the intended purpose of R17/R18. Still a note on the schematic would be nice. I will desolder R17 (RXD0) and see what happens with the programmer.

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