sending digital data to an atmel arduino

[toxibunny]

Okay, so I took a big bite. Hopefully not more than I can chew, but I'd like a bit of help please - I got a few metres of 'dumb' RGB LCD strips off of ebay because they're so cheap - just over 10 pounds for 3 metres!

...so then I needed something to drive them. I got a power supply too. But I didn't want the just white or just red or whatever - I needed a PWM controller. now, a Pi can kindof do that, but I wanted one for each window, so I got a couple of TLCsomethingsomething LED controller ICs, and a few MOSFETs, and figured I'd plug my pi into those.

...but soon realised that the TLC chippy things would need some precise timing otherwise it would look crap. So I bought a couple of atmel328 chips (not full arduinos because I'm a cheapskate), and that'd be the end of it.

Actually, no. I got a couple of CD4050 hex buffer converter thingies while I was on, because I wanted to use it with the pi safely and maybe even use the ADCs on the atmel chips so I could control things with a couple of nice twiddly potentiometer knobs I got earlier. With me so far?

so:
Pi>CD4050>Atmel 328P>TLC5940>Power supply+MOSFETs>RGB LED strips
and also:
Twiddly knob Pots>Atmel328P>CD4050>Pi.

got a couple of breadboards too, to stick things in.

Now, I think I'm mentally mostly in the ballpark with regards to the physical circuitry, power, and programming the atmel. The main thing I'm missing though, is communication between the Pi and the atmel - I just want to use some nice familiar friendly python to send control data to the atmel. Just a string of bytes or whatever - I'm thinking that I'll program it to keep repeating the same data to the LED control chips, over and over unless it receives data from the Pi, at which point it'll repeat that over and over instead...

It probably won't need too much bandwidth - 20 channels * 12-bit data, 100 times per second. Something like that.

Does anyone know what the best way to go about it would be?

[joan]

Say 30,000 bits per second? Well within the capabilities of a serial link. You'd have to level convert between the Pi's 3.3V and the Atmel's 5V though.