I developed a board / app. for a client using '64A3 and MKII ISP unit. I got it to work without using a pullup on PDI's reset.I built the 1st brd. and it worked, then got damaged( xmega toasted ). He wanted 2 boards ttl. and the 2nd board uses a '128A3 as a replacement, Digikey's out of stock on '64A3. NOW I can't access either one !!
1) With no p.up, the ISP'orange led blinks ( didn't do that before ).
2) with a p.up of 1K, or 4.7K or 10K, the led's steady green, but I can't even read signature ( voltage is read correctly ). Studio's error msg. says check I/F connects.
3) Once I did reverse-connect Vcc -- PDI_data and Gnd.--PDI_clk. wires to the ISP, BUT I still got the #1 behavior before I did this. My ISP unit, made in 2009, still works on tinys and megas. Additional tools are 1) and 2) from my sig and 3.4 V system.
Any ideas ?