AtTiny202 same problem "link UPDI not OK Reinitialization required" - solved

[gpreviato]

Hi guys, just to inform you that we had the same problems, but the cause wasn't related to the software.
We used some pl2303 usb-serial converters with the 'low' level too high to be reconnized by the Attiny and a really noisy 3v3 power supply (200Khz sawtooth, probably due to the internal DC/DC converte missing cap).
We solved it using a ceramic capacitor between GND and 3v3, that also stabilize the TX and RX voltage.
The Low level was at 1.18 volts. We solved the problem adding a bulk pnp, drived by TX, between the RX line and GND.
After this simple operation everything works great.
I made a simple explanation, with scope details and the used schematic, here:
https://www.xtendsenses.com/en/analisys-of-a-low-quality-usb-serial-converter/

[mraardvark]

Thanks for sharing @gpreviato !