I was configuring several Pins as Input on the 52259 Tower Module.
How I got it from the manual this is the default state after reset anyway and in GPIO mode all pins have an internal pull up activated. Is that correct?
Now it all seems to work out fine, the pins show a 3.3V level on the scope, they can be pulled to ground without problems and I can read the state via the corresponding registers.
Except for PTA3 (Pin 58 on the LQFP144). On the scope, I read a constant 0,25V. It can't be pulled up with a 10k resistor so there seems to be some drive strength behind this. Browsing the manual i found that the pin has some extra functions in GPT mode, but again after reset these shouldnt be active. I still explicitly tried to disable the GPT features and configure the whole PTA port for input, also activate the GPT pullups, but that had no effect. Here is the code:
MCF_GPT_GPTSCR1 = 0; MCF_GPT_GPTSCR2 |= MCF_GPT_GPTSCR2_PUPT; MCF_GPT_GPTDDR = 0; MCF_GPIO_DDRTA = 0; MCF_GPIO_PTAPAR = 0;
Other than the 52259 board, only the TWR-SER is plugged into my tower. According to the schematics, PTA3 is connected to PWM7 (B37) on the PCI connector which is not connected at all on the TWR-SER board. Also, PTA3 aint used on the MCF board (for LEDs or the like), it simply goes straight to the PCI connector (I checked the Gerber files).
All code is simply the default project that was generated by CW 7.2. That is actually enough to reproduce the issue: I have CW 7.2 create a new 52259 project with main() just running the endless for() loop. When i compile and run that, the ports I checked do indeed default to pulled-up input ports but PTA3 wont. It does instead still drive the 0,25V.
Can anybody confirm this behaviour, did I (most likely) just overlook something or is it that maybe my MCU board is defective?
Thanks for your time,