I have troubles with programming ATtiny816 on my custom board.
Am unable to program it using ATMEL-ICE, no operation works including Read_Signature, Erase,..
My header for programming contains:
+5V = connected to VDD pin of micro
GND = connected to GND pin of micro
UPDI = connected to pad 19 of micro, i.e. PA0_UPDI_RESET
My programming cable interconnects header signal UPDI with ATMEL-ICE/AVR-port/pin_3 (TDO).
This type of cable worked well with ATtiny817 Xplained board;
(I had removed one resitor that interconnects mEDBG_chip <---> ATtiny817/pin PA0_UPDI i.e. disabled programming via mEDBG and enabled programming via ATMEL-ICE, to check it works..).
Is there any reason why it shouldn't work the same way with ATtiny816 ?
I measured the pin PA0_UPDI and there appear some 3 pulses about 2us long on Read_Signature. But always fails.
Before these pulses and after them it seems to be floating or voltage around 1.8-2.3V, is it necessary to have any Pull-Up or Pull-Down connected to this pin ?
If anybody successfully programs ATtiny816 or similar chip (via UPDI), please share your circuit diagram. I am lost.