Hello everybody, I hope to find help here… I’m trying to flash esp home on an esp32 relay board bought on AliExpress. The usb is not for flashing, and when I connect the cable carries on to turn on and off the relay repeatedly (Is it normal??).
Then, I need to flash it with TTL… but I’m not so good to do this, can somebody help me? Here is the board:
Is your USB to TTL 5V tolerant? Can it run on 3.3V?
To flash:
GND → GND
TX → RX
RX → TX
5V (or 3.3V) → VCC
With the jumper between GND and GPIO0 (I00 on your board) the device is in flashing mode. Once it successfully loads, remove the jumper.
Your main concern should be whether the USB - TTL chip uses 5V logic levels - if it does then you can damage the ESP. Use a converter specifically designed for ESP rather than Arduino. Many let you switch voltages. Then add a header to the 3.3V pin and connect VCC to that.
This is the datasheet, or at least what I found…
Model: SH-U09BL
Main chip: Silicon Labs CP2102N
Pin Definition: RXD,TXD,GND,VCC,CTS,RTS
Output VCC: 5V
TTL Logic Level: 3.3V
USB interface: 2.0
The maximum speed: 3Mbps
Thank you for your help!
Should be fine to connect VCC to the 5V pin then.
Which cable? The USB or the TTL? I suggest removing the jumper, you can manually short it just before the ESPHome install gets to the bit where it uploads.
Zoogara, thank you very much for you help. Everything works perfectly! 
Hi there. I am using the same esp with relay. Cant flash anything. Appreciate some advise. The usb to TTL is CH340G. Am I using a wrong TTL for this ESP32?
A fatal error occurred: Failed to connect to ESP32: No serial data received.
