Daniel DeLuca

Untraceable Serial Port shutdown

Discussion created by Daniel DeLuca on Apr 28, 2006
Latest reply on Apr 28, 2006 by Daniel DeLuca
For some reason, the serial port on the MC9S12DJ256B 80 pin package occasionally shuts down and refuses to respond to input. I fixed the general case, but it still occurs after a power outage. The $#&!(@%& thing is supposed to reset on startup, but occasionally it hangs. I trapped the hang with the debugger, a few times. Twice, I found it pointing to RAM memory, and a third time, it was pointing to the INTERNAL REGISTERS. I set up ENABLE_COP_X at the entry point, but when I checked the associated memory location, it shows this register is disabled, as if it were never set. When it doesn't hang, but operates semi-normally, it occasionally shuts off the serial port. Trapping it with the debugger, makes the problem disappear, without giving a clue what caused the problem in the first place. This is embarassing; it makes us look really bad.