I designed a circuit around the MC9S12DT128BMPV. I'm using an external 16MHz clock. When I power up there are some erratic square wave signals on the I/O pins. It seems like it is going through some type of continuous reset. I have the reset line pulled high with a 5K resistor. CW with a Cyclone can't communicate. Any ideas?
Hi Gerry,
I would like to recommend you an app note, the AN2727 Designing Hardware for the HCS12 D-Family:
cache.freescale.com/files/microcontrollers/doc/app_note/AN2727.pdf
Kindly go through it and check if you have anything different than stated in the app note such as:
- Power supply connections
- Control pin connections
- Oscillator options
etc.
Regards,
iggi