Representing ports numerically?

teccs · Joined: 14 Oct 2006 Posts: 69

In my code, I receive a number via serial port. Based on that number the code will turn a port on or off. For example, if 1 is received, turn port G.1 off. If 2 is received, turn port G.1 on.

I have to handle about 30 ports like the above with different numbers coming from the serial port to tell what port to do what with.

My current method to handle this is using a SELECT CASE statement with about 60 cases.

Is there any way to handle this numerically or with an array()?

It would clean up the code a bunch if I could get rid of the huge SELECT CASE setup.

Thank you!

Tim.

(BASCOM-AVR version : 2.0.8.2 )

albertsm · Joined: 09 Apr 2004 Posts: 5921 Location: Holland

that can only be done when there is some logic to the system.
for example, all even numbers do something and all odd numbers do something else.

then it depends on the processor used if it can be done simple or not. unfortunately normal AVR processors do not have a logic to the port numbering. Xmega do have.
so as always, you need to show processor and some code in order somebody can help you.

teccs · Joined: 14 Oct 2006 Posts: 69

Thank you for the reply.

I can use any numbering scheme or logic that would work well.
Code is below.

albertsm · Joined: 09 Apr 2004 Posts: 5921 Location: Holland

if you are free to use anything you can consider the following : let the on/off be part of the number. meaning that even numbers means off. and odd numbers mean ON.
but you can also encode things. for example you need 1 bit to turn on/off. then you have port A,B,C,D,E,F,G which are 7 ports. meaning that you need 3 bits to specify the port.
and you have 8 bits which mean you need 3 bits again. thus using 7 bits you can set everything.

0xxx Z yyy
xxx=0- porta, 1-portb etc
yyy=0 bit 0, 7-bit 7
z=0 is off, 1=on

you can work that out on the sending side.
then on the decode :

bState=B.3 ' get state where B is the coded byte, bstate will be on/off
index=b and 7 'get index
prt= b and &HF0
swap prt 'get the port number

select case prt
case 0 : portA.index=bstate
case 1 : portB ....

that is it.
it might have some errors since i did not test and wrote it down. but it is simple to test in the sim.

teccs · Joined: 14 Oct 2006 Posts: 69

I will give this a try.