[img]I have made a custom esp32 board. For schematic, i have used sparkfun link-https://www.sparkfun.com/products/15006 The problem is- the arduino code is not uploading on the custom esp32 board. So, how i can upload the code on esp32? Is arduino bootloader is required first for bootloading the bla...

I have come across exact same thing with ModbusMaster library as well. Too many Modbus and Logic analyser tests lead me to editing of the library and found the solution actually. Problem is according to my guess, when you use Serial.write() function, due to async nature of ESP32 it doesn't wait for...