Monte Variakojis

MC9S12DJ256 - Reset asserted low at power-up

Discussion created by Monte Variakojis on Jan 21, 2008
Latest reply on Jan 23, 2008 by Jim Donelson

Hello Group,


I'm the software guy working on a new board and the hardware guy is telling me that this is a software problem. I'll help him in his quest.


We have built a few prototype boards (10) and six of them cannot communicate with the BDM. The other four do. I've check that there is a clock and that there are no shorts. The strange thing is that the reset seems to be asserted low and stays there on some boards.


1. Why would the CPU reset pin be asserted low and stay there?


2. The BDM claims that there is no clock or it is not connected to the CPU. What are some of the items I should be looking for to figure out why the BDM does not communicate?


Thanks for your help.