Joseph Stepien

M5213 spurious interrupt?

Discussion created by Joseph Stepien on May 12, 2006
Latest reply on Jun 1, 2006 by Joseph Stepien
I'm using a M5213EVB eval board in CodeWarrior IDE.  I have all UARTs configured and a timer tick on PIT0 at 1000 Hz.  Without the PIT0 ISR enabled I can reliably receive and transmit data on any of the UART channels via UART ISRs.  However, with PIT0 enabled I'm getting what I'd characterize as a spurious interrupt at vector 127 which prints out a debug msg to UART0 stating "User Defined Vector #127" but only after having attempted to transmit data via my UART ISR.  Without any serial data received or transmitted the PIT0 operates at its programmed rate (reliably switching tasks).  I don't have this bit for vector 127 masked on in IMR so 1.) I don't know why it's even vectored to. 2.) I can't account for any inconsistencies in my setup of PIT0 that might be causing this.
 
I've tried to reset the PIF bit of PIT0 initially by writing to PMR register with reload value (even though I've configured RLD bit to 1) and then changed that thinking that could be the problem by instead writing 1 to PIF bit to clear PIF flag.  Neither has prevented the 'spurious' condition.
 
Anyone have any ideas what might be causing this interrupt 127?  I've checked documentation reference about possible spurious interrupt conditions concerning the SR register but there doesn't seem to be a conflict.
 
Thanks.

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