[dorkbotpdx-blabber] Arduino - reading digital pins as a number?

[Hans Lindauer]

Thanks Don, that worked (once I RTFM and figured out how to enable the 
pullups).

Donald Delmar Davis wrote:
> I am not sure if my initial response answered your questions directly. 
>  
> 1. No unless there is some compelling reason to connect the switches 
> to vcc go the other way and connect your switches to ground.
> 2. if you do this then the internal pullups on the port pins will 
> handle this correctly.
> 3. given that your pin selection actually spans two io ports then 
> digital reading the pins is as good as any.
>
> Don.
> On Jan 1, 2009, at 3:49 PM, Hans Lindauer wrote:
>
>> A few easy questions for those in the know.  I have a DIP (SIP, 
>> actually) switch connected to pins 5-8 of my dorkboard(s) and to +5V, 
>> and want to read in the switches as as number.
>>
>> 1.  Can I safely connect +5V to a digital input (or 4), and leave it 
>> high for an extended period without having to worry about overheating 
>> or other issues?  Probably a dumb question, I know, but I'm still 
>> learning the ins and out of this stuff.
>>
>> 2.  Do I need pull-down resistors to ground on each of the digital 
>> pins?  I guess I don't understand the necessity of that.  Also, is my 
>> terminology correct?
>>
>> 3.  What's an elegant way to read those pins in as a byte?  I know I 
>> can multiply the pin value by 2^n and add them all up, but it seems 
>> like there's got to be a smarter way.  Maybe I can read a register 
>> with the pin values and mask off those bits?
>>
>> Thanks in advance,
>> -Hans