PIN state VS Variable read

[mister_e]

Well, several way to do it.
1)You could use a Timer interrupt which will read your dipswitch all the time, so in your main code you just need to read the DipSwitch variable.

2) Create a simple subroutine which will read the dipswitch when YOU decide

Now what's the better solution to read them... i will prefer to read the whole port where my dipswitch are attach to and only keep the interesting bits . Let's say i have 4 dipswitch connected to PORTB<3:0> i'll use

DipSwitch = PORTB & $0F

the & $0F is and bitwise AND with 0F hex. this mask <7:4> bit, and keep only <3:0>.. where my dipswitch are connected.

You could still use
DipSwitch.3=PORTB.3
DipSwitch.2=PORTB.2
DipSwitch.1=PORTB.1
DipSwitch.0=PORTB.0

Both do the same job.. i prefer the first one. Which is the faster.. i didn't measure it yet. I feel the first is faster...

HTH

[Dave]

cburtis, Its really up to the way your program is meant to work. If the information from the dip switches can change during the operation of the code then yes you will have to read them during the operation. However if they are some type of preset or an address that is used during the constant operation of the program then they only need to be read once. In the past I have used diodes to common source the switch's so I can also use the pins for other purposes during the operation. The diodes (anodes) are connected to a single pin of the processor so that during the initialization of the code I would place this pin high and read the switches. After reading them I place the line low and away we go.....

Dave Purola,
N8NTA