AnsweredAssumed Answered


Question asked by Kerry Mackenroth on Feb 26, 2010
Latest reply on Mar 2, 2010 by Kerry Mackenroth

Greetings all,


I am completing my PCB layout for our MC9S08LC36 project, and I have an IRQ issue. Since our products are used on motorcycles, they run in a noisy EMI/RFI environment. In the past we have connected the IRQ pin to ground while disabling IRQ Interrupts. This has served us very well.


While researching for our S08 project I came across this note in Fabio Pereira's excellent book, HCS08 Unleashed. Page 210 of  states "The IRQ pin is automatically enabled upon entering any stop mode!" Of course this raises concerns with a grounded IRQ pin. 




* Am I taking this out of context, or is this fully applicable to the three Stop modes?



* Assuming the above has no implications, for EMI "hardening" should I float (no connect) the IRQ pin or connect to ground? Of course, in either configuration the pin will be set to Output, Interrupt and IRQ function disabled.