Hi, I am completely and utterly new to Arduino... My wife wanted me to make some controlled christmas lights for the next holiday and I started research, found the Arduino, ordered one and it arrived yesterday. My plan is to couple the Arduino with a 8 channel 5v relay module.. I have also seen 2,4 and 16 channel relay boards for the arduino.... Is there a limitation that the Arduino Uno can support natively, otherwise I might as well get a 16 channel...
Hi guys, I am new to Arduino, my wife wanted me to make controlled christmas lights so here I am.
My plan is to couple an Arduino Uno (which arrived yesterday) with a relay module (like this one http://dx.com/p/8-channel-5v-relay-module-w-optocoupler-for-arduino-red-blue-223585?tc=AUD&gclid=CLrYndie8rsCFQYepAodJUwA8Q ) .
Since I cannot test programming a relay I dont have, I was wondering if there are limitations to the amount of relays I can control with an Uno... Because If I can control more I might as well go for a 16 Channel.
Any tips, suggestions would be greatly apreciated.
with various other devices, you could control millions of relays.
A 7hc595 shift register will control 8 relays, 2 of them chained together will give 16 outputs (or higher still with 3 or more)
Easy (3 pins to control hundreds of relays)
Please do not cross-post. Topics merged.
Thank Coding Badly, wont happen again.
cjdelphi:
A 7hc595 shift register will control 8 relays, 2 of them chained together will give 16 outputs (or higher still with 3 or more)Easy (3 pins to control hundreds of relays)
Forgive my ignorance.... but is the 7hc595 shift register already on the arduino board?
Eelko:
cjdelphi:
A 7hc595 shift register will control 8 relays, 2 of them chained together will give 16 outputs (or higher still with 3 or more)Easy (3 pins to control hundreds of relays)
Forgive my ignorance.... but is the 7hc595 shift register already on the arduino board?
Uh, no.
If you wish to use just an Arduino, you'd have to turn ALL the pins into digital outputs including the analog ports, A0,A1.... etc which might supply enough pin outs.
cjdelphi:
Uh, no.
If you wish to use just an Arduino, you'd have to turn ALL the pins into digital outputs including the analog ports, A0,A1.... etc which might supply enough pin outs.
Ah, ok, that makes sense...
Since the Uno has fourteen digital pins and another six that can be used for either analog or digital purposes, you'll be fine with a sixteen relay board. Digital pins 0 and 1 are used for the serial port - uploading your code and debugging your application so best not to use them, but even reserving them, you can control sixteen channels with a couple of pins left over.
Thanks Wildbill 
I had a think about it overnight, Ill get an 8 first and then if all goes well buy a 16.... it's not like they cost a fortune...
My wife wanted me to make some controlled christmas lights
Sounds like you figured out how the game works 
Took me 30 years!
A four page tutorial for making a parallel port Christmas light controller, which you could duplicate with an arduino.