AVR-Chat

At last, i have found the problem! It was actually very simple to fix, the
problem was that the adc was enabled by default on the same pins so the
code:
ldi TEMP, (1<<ACD)
out ACSR, TEMP
did the trick.
I wonder why this solves the problem, shouldn't the adc be disabled by
default?
Anyway, this is explained at page 64 in the pdf for attiny26.
Thanks to everyone.

regards, Manne


> A couple of years ago I ran into this with an 8051, and my solution
> was to simply wait for 20ms.
>
> The initial button press would cause the interrupt routine to
> activate. The micro would then wait for 20ms (doing other stuff in the
> meantime of course!), and re-check the interrupt at the end. If the
> interrupt was in the same state, then it was a legitimate button press
> (and not induced noise/etc), and therefore the program should act
> accordingly. Remember as well that when the button is released the
> noise will be present as well, something that bit me on the posterior
> before I took it into account. (Ouch! That took a little while to
> find...."why the !@#$%^&@$^% isn't this $!%^%$@^ working?!?!?".)
>
> You may also wish to consider some IC solutions out there, I think
> (from a hazy memory) that Maxim/Dallas have a keypad decoder chip that
> debounces and decodes the keypress for you, making life a heap easier.
>
> Good luck.
>
> Adam.
>
> --- In AVR-Chat@yahoogroups.com, "Jim Wagner" <jim_d_wagner@...> wrote:
>>
>> Manne -
>>
>> There is a big problem that everyone runs into when trying
>> to sense switches with an interrupt. It is called "switch
>> bounce". It happens fairly slowly compared to the speed of
>> the micro. You get MANY interrupts every time the switch
>> opens or closes.
>>
>> There are several ways to deal with this. One is to "poll"
>> (that is, read) the port pin regularly (maybe once every
>> 1ms or so). Make a little "debounce" counter in software
>> and a bit to remember the LAST state read. Every time you
>> make a poll, compare the current state to the last state.
>> If it is the same, count 1. If not the same, put the new
>> state into the last-state bit.  When the debounce counter
>> reaches some convenient value (say 4 or 8), then the switch
>> state is "stable" and you then do what ever else needs to
>> be done (like increment your LED counter.
>>
>> Jim
>>
>>
>> On Sat, 17 Feb 2007 00:37:04 +0100 (CET)
>>  "Manne Tallmarken" <mannet@...> wrote:
>> > Hi all,
>> > I am trying to make my first assembler program that
>> > handles interrupts. On
>> > PB[6:0] I have som leds and on PA[7:6] i have two
>> > buttons. The leds goes
>> > on with a logic one from the port and the buttons is in
>> > tri-state when not
>> > pushed and goes to logic zero when pushed.
>> > I just trying to get a binary counter to show up on the
>> > leds when i am
>> > pushing the buttons but nothing happens.
>> > Does anyone know what could be wrong?
>> > Regards, Manne
>> >
>> > Here is the code:
>> >
>> > .include "tn26def.inc"
>> >
>> > ; Interrupt service vectors
>> >
>> > .org $0000
>> >         rjmp Reset
>> > .org IOPINSaddr
>> >         rjmp IntPins
>> >
>> > ; define registers
>> > .def TIME=r16
>> > .def TEMP=r17
>> >
>> > ; define constants
>> > .equ PORTB_IO=$7f       ; pb[6:0] = output
>> > .equ PORTA_IO=$00       ; pa[7:0] = input
>> >
>> > Reset:
>> >         ldi     TEMP, RAMEND    ; set stack pointer to
>> > RAMEND
>> >         out     SP, TEMP        ; (SP is one byte on
>> > attiny26)
>> >
>> >         ldi TEMP, PORTB_IO
>> >         out DDRB, TEMP
>> >         ldi TEMP, $00           ; all lights off
>> >         out PORTB, TEMP
>> >
>> >         ldi TEMP, PORTA_IO
>> >         out DDRA, TEMP
>> >         ldi TEMP, (1<<PA3) + (1<<PA6) + (1<<PA7)
>> >                ; enable
>> > pullup resistors
>> >         out PORTA, TEMP
>> >
>> >
>> >         ; set up interrupts
>> >
>> >         ldi TEMP, (1<<PCIE1)
>> >         out GIMSK, TEMP ; enable individual interrupt
>> > PCIE1 ( PB[7:4],
>> > PA[7:6], PA3 )
>> >         ldi TIME, $00   ; start from 0
>> >
>> >         sei
>> >
>> > loop:
>> >         rjmp loop
>> >
>> >
>> > IntPins:
>> >         inc TIME
>> >         out PORTB, TIME
>> >         reti
>> >
>> >
>>
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