ESP32 Forum

Do I need to connect GPIO8 pin to 3v3 to enable "joint download boot mode" ?
I checked all the components on the board and I didn't find anything suspicious

Yes, you do. From memory, a low level on that doesn't affect the USB-serial-JTAG device though.

I tried to connect to esp32c3 chip using UART

UART ---> ESP32C3
3v3. --> 3v3
GND. --> GND
RX --> TX (UOTXD)
TX. --> RX (UORXD)
3v3 --> GPIO2

Press and hold BOOT. (D9)
Press and release RESET. (EN)
Hold BOOT for another ~1s then release.

But:
C:\Espressif\frameworks\esp-idf-v4.4.7\examples\get-started\hello_world>idf.py -p COM5 -b 115200 flash
Executing action: flash
Running ninja in directory C:\Espressif\frameworks\esp-idf-v4.4.7\examples\get-started\hello_world\build
Executing "ninja flash"...
[1/5] cmd.exe /C "cd /D C:\Espressif\frameworks\esp-idf-v4.4.7\examples\...s/esp-idf-v4.4.7/examples/get-started/hello_world/build/hello_world.bin"
hello_world.bin binary size 0x25fc0 bytes. Smallest app partition is 0x100000 bytes. 0xda040 bytes (85%) free.
[2/5] Performing build step for 'bootloader'
[1/1] cmd.exe /C "cd /D C:\Espressif\frameworks\esp-idf-v4.4.7\examples\get-started\hello_world\build\bootloader\esp-idf\esptool_py && D:\Espressif\python_env\idf4.4_py3.11_env\Scripts\python.exe C:/Espressif/frameworks/esp-idf-v4.4.7/components/partition_table/check_sizes.py --offset 0x8000 bootloader 0x0 C:/Espressif/frameworks/esp-idf-v4.4.7/examples/get-started/hello_world/build/bootloader/bootloader.bin"
Bootloader binary size 0x4e80 bytes. 0x3180 bytes (39%) free.
[2/3] cmd.exe /C "cd /D C:\Espressif\frameworks\esp-idf-v4.4.7\component...f/frameworks/esp-idf-v4.4.7/components/esptool_py/run_serial_tool.cmake"
esptool.py esp32c3 -p COM5 -b 115200 --before=default_reset --after=hard_reset write_flash --flash_mode dio --flash_freq 80m --flash_size 2MB 0x0 bootloader/bootloader.bin 0x10000 hello_world.bin 0x8000 partition_table/partition-table.bin
esptool.py v3.3.4-dev
Serial port COM5
Connecting......................................
A fatal error occurred: Failed to connect to ESP32-C3: No serial data received.
For troubleshooting steps visit: https://docs.espressif.com/projects/esp ... oting.html
CMake Error at run_serial_tool.cmake:56 (message):
D:/Espressif/python_env/idf4.4_py3.11_env/Scripts/python.exe
C:/Espressif/frameworks/esp-idf-v4.4.7/components/esptool_py/esptool/esptool.py
--chip esp32c3 failed
FAILED: CMakeFiles/flash C:/Espressif/frameworks/esp-idf-v4.4.7/examples/get-started/hello_world/build/CMakeFiles/flash
cmd.exe /C "cd /D C:\Espressif\frameworks\esp-idf-v4.4.7\components\esptool_py && D:\Espressif\tools\cmake\3.23.1\bin\cmake.exe -D IDF_PATH="C:/Espressif/frameworks/esp-idf-v4.4.7" -D SERIAL_TOOL="D:/Espressif/python_env/idf4.4_py3.11_env/Scripts/python.exe C:/Espressif/frameworks/esp-idf-v4.4.7/components/esptool_py/esptool/esptool.py --chip esp32c3" -D SERIAL_TOOL_ARGS="--before=default_reset --after=hard_reset write_flash @flash_args" -D WORKING_DIRECTORY="C:/Espressif/frameworks/esp-idf-v4.4.7/examples/get-started/hello_world/build" -P C:/Espressif/frameworks/esp-idf-v4.4.7/components/esptool_py/run_serial_tool.cmake"
ninja: build stopped: subcommand failed.
ninja failed with exit code 1

Okay, that likely means that your ESP32 isn't booting up properly. If you have an oscilloscope, I'd suggest probing the crystal to see if it does anything (i.e. if there's a 40MHz signal there). If that's there, see if there's any activity on U0TxD just after reset. If not, check if power, ground and reset makes it through to the ESP32C3. (For instance, we've had cases here where people forgot to connect the EPAD to ground.)

Yes absolutly. You need to connect GPIO8 to Vcc through 10k resistor to enable boot mode.

My schematic is missing VDD_SPI which is not being supplied with 3v3. will this have any major impact on the firmware flashing process resulting in the error I am getting?

My schematic is missing VDD_SPI which is not being supplied with 3v3. will this have any major impact on the firmware flashing process resulting in the error I am getting?

The ESP32 provides VDD_SPI internally, but ideally you'd have a decoupling cap of 1uF connecting it to ground. However, that would not affect the issue you're seeing here: you're not even able to talk to the ESP32C3 and you need to get that fixed before you can worry about the flash.

Hi Sir !
I fixed the above problem by wiring GPIO2 and GPIO8 to 3v3 connected with 10k resistor and now I have problem with antenna when ESP32C3 chip has started Bluetooth, started broadcasting BLE but I can't scan BLE with phone. I tested on another ESP32C3 module and can scan BLE, this proves my code works fine but RF has problem. I hope you can help me double check the components in my circuit diagram have reasonable values?

That's very hard to debug remotely, as it depends on your antenna configuration, PCB layout, etc. You don't happen to have an >8MHz VNA laying around?

I don't have a VNA device
The footprint I used for the BLE antenna is: RF_Antenna:Texas_SWRA117D_2.4GHz_Right
I think the problem is that the L1 and C12 values ​​are not matched, is this correct?

There's a lot more wrong with the PCB. You're running a data trace under the (sensitive) crystal, I don't see the matching caps anywhere near close to it, your (very sensitive, should be as short as possible!) LNA line meanders everywhere and has vias in its path; it's also not impedance matched, you have almost zero ground stitching, and those are just the issues I see at first glance.

I'm gonna be honest with you: I don't think this PCB can be saved. Even if you can figure out and fix the things that make it not work at all, the rest of the issues will still lead to a bad performance, and given you don't have a VNA, you're flying blind as to why it's not performing to begin with. One thing you can do is design a new PCB and religiously follow the design guidelines of the ESP32-C3, but if you excuse me inferring your RF knowledge from your current design, I think you'd be better off using one of our modules (or this one) instead; we have them as they make sure the deeper RF magic is correct in them and you only have to worry about placing the antenna properly.