Using Port DD as GPIO on MCF5282

I’ve got a MCF5282 that I’m trying to use PDD4 as a GPIO on. In my setup code, I’ve got:

MCF5282_GPIO_DDRDD = 0x10;    /* cs on dd4. */
MCF5282_GPIO_PORTDD = 0x10; /* active-low. */

And in my main loop开发者_开发问答, I’ve got:

MCF5282_GPIO_PORTDD = (mainloop_cnt & 0x10);

Which should give me a nice square wave on the oscilloscope, but the port doesn’t seem to be doing as I say. Am I missing some setup steps? I can’t find anything in the 5282 manual about a “Port DD pin-assignment register” to repurpose it from its “primary” role as DDATA.

Edit 2011-03-01: We never figured this out, we just used a different pin for GPIO.

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You probably need to clear PSTEN in the Chip Configuration Register to disable DDATA, see page 27-4 of the MCF5282 and MCF5216 ColdFire Microcontroller User’s Manual