Driving a Signal High or Low

[jsmithown]

https://www.axman.com/support/CME-12D60/CME12D60Csch.pdf <---schematic
https://www.axman.com/support/CME-12D60/cme12D60man.pdf <----manual

I am trying to design a circuit that will drive the RESET# pin low (aka reset the microprocessor). The HC12 board is at school. But, sometimes I remote desktop to the school's computer (while I am at home), and the HC12 hangs. So, to reset it I would need to drive to school to reset it.

Since the HC12 is hanging, this circuit needs to be external and not depend on the HC12.

I need this process to be either software driven (from PC) or a timer that will reset the HC12 if there is no activity.

Can someone help me design a circuit? My initial approach was to use a transistor to drive the RESET# signal low after 100 seconds, but it did not work out too well.

Thanks!

 

[IanP]

You can use DS1232 from Maxim-IC ..
It is proffessional MicroMonitor IC which incorporates watchdog-timer ..
**broken link removed**
**broken link removed**
All what you need is to do is to identify microcontroller's pin which stops making transitions after the micro gets into troubles (maybe AS* signal) and connect it to the DS1232 ST pin, and connect the DS1232's output (RSR or /RST) to the micro's reset pin ..

Regards,
IanP

 

[jsmithown]

Thanks for your suggestion! But, I would have a circuit that can be designed. I am poor and I cannot wait for the product to ship.

Any ideas?

Thanks again