MCF51QE128RM Reset on input

[FredT]

Hi, I'm working on a MCF51QE128RM with CW for Microcontrollers V6.1 and there's an input in Port D (PTDD4) that result in a reset when I push the button liked to the input repeatidly.

The port is configure in input with an internal pull-up. I have disable the interrupt for the input by setting KBI2SC, KBI2PE and KBI2ES to 0x00.

When in debug, I notice that in the command window, there is a message saying "Frequency change to ~8978805hz" when the device reset. This is not the frequency I have set the device to, and when I'm starting the debuger, there's a message saying "Frequency change to ~22109775hz" which is the right frequency.

Also, when the device is halted in debug, I'm pushing the button repeatidly and the device reset. I had the reset on low voltage disabled, and it doesn't fix the problem. I also have others inputs on the Port D using the same button and they are working fine.

Thank you and have a nice day

Fred Talbot


Message Edited by FredT on 2008-02-14 01:52 PM

[BRUNONUNES]

Some resets happen  because of "clock  loss",  try to use debugger to trace instructions, this kind of reset occurs when microcontroller are running a normal instruction(and we can see no reason). Try to use internal clock module maybe it helps you.

Best regards,
Bruno

[FredT]

Thank for the info, but I finaly found that the clock isn't changing. I'm having RS232 communication with my computer and the communication is still working fine after the trouble.

I also found that when I disable the reset pin of PTA5, the PTD4 button is working fine and don't reset the device. I have tried to configure the PTA5 pin in input and pool the value of the PTA5 pin when I'm pushing the PTD4 button, and the input state is always at false, so it doesn't seem to have interference between those two.

I'll try to have the PTA5 pin configure with an interrupt to be sure.

Fred Talbot

[FredT]

I just saw in the MCF51QE128RM reference manual the note : RC filter on RESET/IRQ pin recommended for noisy environments.

I'll try this for now, but I don't know how that explain that the device reset when I use the input in IRQ mode too oftenly.

Fred Talbot

[FredT]

Finaly I probably have done something wrong cause there's no reset when I configure the RESET pin in IRQ, and when I add a low-pass filter, the device is working fine.

So you should use a RC filter on the RESET pin, even if you think you don't have a noisy environment.

When the device resets, there's a message "Frequency change to 0hz" which tells us that the device is in reset, and then "Frequency change to Xhz", which tells us the device is restart, but the second frequency doesn't seems to be right, because I'm having a serial port connected to my computer and the communication is still working fine even if the X frequency is like the third of the original value.

Fred Talbot