I've designed a board to use the ADUC841. The original used the ADUC831, and the newer one is meant to use the ADUC841.
On the same board I can program a ADUC831 but not an ADUC841. I've tried this on two board, with the same result, which means that a similar soldering problem is happening or there is a design issue.
My understanding from the datasheet is that the 831 and 841 are pin compatable.
I'm using WSD to program the chips.
I've checked the voltages DVdd and AVdd are both 3.3V.
i'm pulling Psen down with a 1k resistor.
My clock is running at 11.0592Mhz making a good 9600 Baud rate.
Looking on the board I see the PC transmit some data. The 841 does not respond.
Any ideas where I should look?