WS2801 controllers

[Matt_Edwards]

These chips are used in the commercial Pixels. They offer 3 channels of 8bit PMW with programmable constant current source. At a street price of 20cent each they are also damn good value.
I am thinking of a small remote controller


Basic Spec:
3ch
30mA Constant Current
12 to 24v operation OR
5V only



Parts cost are around 3.00 in PWB but exc the 24 to 5 SMPS. I haven't decided on the PS yet. AND you will need a DMX 2 SPI Bridge with RS422 driver capability.

So any thoughts?

[Entropy]

Got a datasheet by any chance? What's your source? (Since you're in AUS, the feasibility of these might not be so great in the USA where they are VERY difficult to source.)

[n1ist]

http://dhsdz.com/upload/file/1258863693.pdf

[dirknerkle]

Interesting idea. There seems to be no end to the wonderful creativity of our good friends down under! Those of us up here in the "brain-freeze tundra" will be watching your progress as development continues!

-dave

[Matt_Edwards]

n1ist - that is the data sheet - thanks
source is for the chips is Alibaba.com
All the pricing below is based on 100 off units.

if it is not clear, the RS422 chips are only used to increase cable length between chips. most applications have them about 15 to 20cm apart.
I am thinking more than 100cm.

The 30mA limitation sort of determines there application - a singe string of LEDs. if you want more I suspect you would be better using an small AVR tiny or even a FPGA with a fet and constant Curent source.

[mrpackethead]

Hi, we will be releasing the tested 2801/6803 string driver design on Monday. Check out www.response-box.com/rgb for details. PCB only will be available for order. It will drive four separate strings, driven by a DMX input. All other parts are easily obtainable from your favourite supplier.

Construction is in SMD, however the smallest parts are SOIC, so if you've never done SMD, its not something to get too scared about.

Source code will also be avaialble, so this is truely open.

[smartalec]

i thought spi was 6meter between chips, or is that between chips an the controller, i was going to run them from phils an tabor tiger pb.

These chips are used in the commercial Pixels. They offer 3 channels of 8bit PMW with programmable constant current source. At a street price of 20cent each they are also damn good value.
I am thinking of a small remote controller


Basic Spec:
3ch
30mA Constant Current
12 to 24v operation OR
5V only



Parts cost are around 3.00 in PWB but exc the 24 to 5 SMPS. I haven't decided on the PS yet. AND you will need a DMX 2 SPI Bridge with RS422 driver capability.

So any thoughts?

[Matt_Edwards]

i thought spi was 6meter between chips

I doubt that. it is just a plain digital signal, running at speeds up to 25MHz.

[Tabor]

Actually according to the data sheet, SmartAlec is right.

Not specifically about SPI,but in regards to these chips.

Spec say 6 metres at 2Mhz clock rate.

Now whether or not it is possible in real life is another matter.
I imagine a slower clock rate would be required for longer distances.

[mrpackethead]

Actually according to the data sheet, SmartAlec is right.

Not specifically about SPI,but in regards to these chips.

Spec say 6 metres at 2Mhz clock rate.

Now whether or not it is possible in real life is another matter.
I imagine a slower clock rate would be required for longer distances.

I have done 7m at 1.2Mhz, but its not that tolerant to external noise.