[PD] Arduino+firmata - digital input (pull-up) - for Hans
Martin Peach
martin.peach at sympatico.ca
Fri Apr 27 03:05:15 CEST 2007
Hans-Christoph Steiner wrote:
> On Apr 26, 2007, at 9:45 AM, João Miguel Pais wrote:
>
>
>> Hello Hans and list,
>>
>> we're in the workshop with Sukandar in Berlin, and something
>> strange just
>> happened. My arduino isn't the newest, it has with the ATMEGA8 chip
>> (the
>> one we got in Zürich some time ago). I've put the latest firmata
>> into it,
>> and the analogue stuff worked quite well.
>>
>>
>> While doing some digital inputting (just simple switches) a few things
>> happen:
>>
>> - the inputs/outputs don't match: if the switch is connected in the
>> input
>> 2, it comes out from 5 (the same to all other inputs, although I
>> didn't
>> mapped them). But consequently, if I switch the input 2 off, the
>> output 5
>> switches off.
>> This doesn't happen on other participants who have the newest arduino
>> board.
>>
>> - someone here mentioned that the arduino has its own pull-up
>> resistors.
>> but in the firmware they're switched off, and we found no
>> possibility to
>> switch it in the arduino-test patch. so we must build our own pull-up
>> resistors in the circuit, outside.
>> is it possible with this firmata to activate the pull-up resistor in
>> arduino from the pd patch? if not, do you think you're going to
>> implement
>> it? or could you tell just quickly how enable it?
>>
>
> Hmm, I am still mostly working with the ATMEGA8 boards. I am unaware
> of a way to disable or enable pull-up resistors in the ATMEGA8/
> Arduino. If such is a thing is a possibility, I would happily add it
> to the Firmata firmware.
>
>
In the atmega8, you activate the pull-up by writing a one to the port
pin, as long as that pin is in input mode, and the PUD bit in SFIOR
hasn't been set.
It has no bearing on the bit-scrambling, that sounds like an endian
issue between versions of pduino code.
Martin
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