This circuit provides a simple means to program ESP based boards. It is specifically designed to work with the Shelly product range with a 5 pin and 7 pin header. The 5 pin connector works with our various PCB designs as well.
To flash tasmota there is a web page (works on Chrome) which works directly with this. The only extra item you need is the USB lead from your computer to this PCB (USB-C connector).
Tasmota flash page: https://tasmota.github.io/install/
Buy on Amazon: https://www.amazon.co.uk/dp/B0C15K9ZC4