topic n00b Question about AN Port, GPIO and reading 8 bit words in ColdFire/68K Microcontrollers and Processors

n00b Question about AN Port, GPIO and reading 8 bit words

jab — Wed, 17 Feb 2010 21:11:17 GMT

ok so i've been working with MCF52235EVB for some time now. i now want to build my own MCF52235 PCB to do some stuff. one of the things I need to do is read 16bit parallel words. so i thought i could use one port to read 8 bits MSB and another port to read 8 bits LSB.

i read through the reference manual and see that analog port (PAN[0:7]) and the interrupt port (PGP[0:7]) are two seven bit ports. so i can set these two ports to be GPIO and digital inputs and read in the words.

is this the right way to do this? any obvious mistakes?

Re: n00b Question about AN Port, GPIO and reading 8 bit words

scifi — Wed, 17 Feb 2010 21:56:41 GMT

When you were saying "seven bit ports" you must have meant "eight-bit ports."

Yes, you can read a byte through one 8-bit port and the other byte through the other 8-bit port. You have to make sure the 16-bit word is stable while you are sampling it (the two 8-bit reads cannot be simultaneous.)

Otherwise, it's ok.

Re: n00b Question about AN Port, GPIO and reading 8 bit words

jab — Thu, 18 Feb 2010 15:01:14 GMT

eight bits yes, thanks .