mysterious malfunction when using PEEK with atmega2560

[louie]

hey guys i got some wierd !#$@ here i'm tryin to read PORTC using the peek command:
first i set PORTC to in and pullup

dir PORTC.0 in
set PORTC.0 on
dir PORTC.1 in
set PORTC.1 on
dir PORTC.2 in
set PORTC.2 on
dir PORTC.3 in
set PORTC.3 on
dir PORTC.4 in
set PORTC.4 on
dir PORTC.5 in
set PORTC.5 on
dir PORTC.6 in
set PORTC.6 on
dir PORTC.7 in
set PORTC.7 on

then i read the port by using peek:

    if (peek(40) = 255) then    ' 40 is the address of port C on atmega2560
      DMXCHAN(8) = 0              'this is a LED light. 0 = off
    end if
    if (peek(40) < 255) then   ' if i ground one of the pins, it goes low
      DMXCHAN(8) = 255            ' 255 = on
    end if

then i take a wire and ground one of the PORTC pins, but nothing happens. the light won't come on.
then i change to this:

      if (PORTC3 = 1) then
        DMXCHAN(8) = 0
      end if
      if (PORTC3 = 0) then
        DMXCHAN(8) = 255
      end if

now it works. ground out pinC3 and the lite comes on. but i gotta figure out why the peek does not work. anybody know what's up?

[Anobium]

Dont peek - in all my years.. never used peek. Simply use PINC. See the Help Inputs/Outputs.

[louie]

ok i'll check that......
well i don't follow what it's saying about the specific syntax of uservar = pinx
i have to do a for loop. so will it work if i do this?

for x = 1 to 10
array(x) = pinx
next

[Anobium]

No. Is there 10 ports on the microcontroller you are using?

Something like this... this is portable code - no peek. It may be faster to simply assigned the pin to the array element.

PinState = PortC
for LocalVar = 1 to 10   'do not use x character vars
        pinArray (LocalVar) = PinState.0
        Set C off
        rotate PinState right
next

[louie]

no there's actually 69 pins that i have to address via a FOR loop.
every pin on the mega board. ports A thru L
so i had an array of port memory addresses and a for loop like
" for xx = 1 to 69
localvar = peek(addresses(xx))"
but that didn't work because peek(address) always returns 255 regardless of the state of the pins.

[stan cartwright]

Do you monitor each port bit then stop? else localvar will always be port 69.
Please explain your plan in more detail.

[louie]

well here's a simplified example:

dim addresses(3)
addresses = 34, 37, 40          ' ports a b and c
dim pins(3)
mask = 0b01101001
for xx = 1 to 3
  inbyte = peek(addresses(xx))
  pins(xx) = inbyte & mask
next

problem is that peek doesn't work. so the code that Anobium posted above will work, but only for a single port.

[stan cartwright]

it's late. not elegant.

dim result(24) as byte 
for count=1 to 24
  pbit=fnlsl(1,count%8)
  if count/8=0 then result(count)=porta and pbit
  if count/8=1 then result(count)=portb and pbit 
  if count/8=2 then result(count)=portc and pbit
next count

[louie]

yeah..... that's damn clever. and it's probably as elegant as it's gonna get. cause it looks like there's just no way to numerically reference those ports, at least not with GCB.
THANX, stan. i'm gonna use your routine and get back to the job.
mike :-)