topic reading I/O ports problems in CodeWarrior for MCU

reading I/O ports problems

LEGION55 — Fri, 21 Mar 2008 05:58:21 GMT

hi guys thanks for your help. look I'm new in this and Im working with the gp32 from hc08 family and I need to read from the port a and the port b two numbers, the question is

how can I read from the the ports of the gp 32 and save the data in the register A, and how can I write some value in the some port?.

thanks I work with codewarrior 6.0

please help me!!

Re: reading I/O ports problems

LEGION55 — Fri, 21 Mar 2008 06:00:00 GMT

oops ....please is in assembly not in c or c++ thanks

Re: reading I/O ports problems

jorge — Tue, 25 Mar 2008 22:55:29 GMT

LEGION55>

Since you didn't show any code, it couldn't be considered as a problem itself.

Did you configured your I/O ports?

Are you reading incorrect or spurious values?

Do you write something to your port but you can't see anything?

Which I/O port or device are you using?

I think this task could be accomplished by reading the "Parallel Input/Output Control" of your device's Reference Manual combined by a good reading in addressing modes (INH, DIR will be a good starting).

Re: reading I/O ports problems

fabio — Tue, 25 Mar 2008 23:22:04 GMT

Hi Legion55,

What about:

LDA PTA ; load A with the state of the PTA pins (remember to configure the pins to input mode)
STA PTB ; store A into the PTB register (write on the PTB pins configured as outputs)

Remember that you need to configure the PTA and PTB pins to the desired mode (input or output) by writting into the DDRA (for port A) and DDRB (for port B). By default (after reset), all pins are inputs.

Best regards,