I have spent hours now trying to catch up on the replacements for the old ATtiny's, there does not seem to be a robust (meaning, with protections that we could find in an UNO or Mega for example) schematic for the ATtiny14 when the use case is the following:
- Board, not breadboard
- MegaTinyCore (huge thanks to Dr.Azzy)
- Programming of Optiboot using one of the programmers a) a modified USB-Serial cable for SerialUPDI or b) an Arduino programmed with the jtag2updi sketch
- To program the board, power cycle it - Optiboot will wait for 8s for a new program to be uploaded over the UART before starting the firmware, so no need for auto-reset
What I have so far is this, but I'm not sure if this is actually reliable or not. I don't think the diode I'm used to putting on RESET for example would work. Also, is the ATtiny14 sensitive to ESD? It doesn't seem to say in the datasheet.
To burn the bootloader, I leave the 2x3 header without jumpers and connect GND + UPDI/RST# to the SerialUPDI device. After burning the bootloader, I replace the jumper between UPDI/RST# and the pullup+ (optional?) capacitor. I expect to be able to just power cycle and hit "program over COM" in Arduino to exploit the newly burnt Optiboot.
Am I missing anything? I would like to get everything right before purchasing the components for the breadboard.
protections that we could find in an UNO... UNO has no protection circuitry \$\endgroup\$