“This little project utilises an ATtiny9 to automatically reset the ESP32 into bootloader mode.
This little project utilises an ATtiny9 to reset an ESP32 into bootmode. It is used when programming the ESP32 with the Arduino IDE.
I thought it was a bit annoying that I had to manually put the ESP32 in to bootloader mode by pressing the buttons. So this hack utilises an ATtiny9 the micro sized 6 pin SOT23 device from Atmel.
It connects to the RXD line of the ESP (TXD from PC) and to the BOOT0 and RESET lines. When trying to upload the program from the Arduino IDE the ATtiny9 detects the bootloader signature that is sent from the PC to the ESP. It then automatically puts the ESP in bootloader mode. So the Arduino IDE can directly program the ESP32 without the user having to press any buttons. The ATtiny9 is super cheap and does not need any external components. I suppose this could also be used for the ESP8266. And it makes the use of the Arduino IDE with ESP32 much simpler. Also only the RxD and TxD lines are needed (with a CH340E for example).”