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  • Author Author: chezdomotix
  • Date Created: Date Created
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  • Comments 4 comments
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Piface Digital with RPI2 & drive 16 lights

chezdomotix

Hello all,

I'm working with an artist to build an animated sculpture with (originally 1 but now) 16 lights driven by RPI 2b because of a king of random algorithm.

At first sight, as there was only 1 light, ans 2 input switch, I've bought a Piface Digital 2 (available) and a Piface PiRack for future HAT sensors.

But now, i need to drive 16 lights, so i said i put the Piface Digital 2 on the PiRack but this don't work because the PD2 is 40 pins and the Pirack is 26 pins.

And unfortunately the Piface Digital (1) which is 26 pins seems no longer available (but on the Piface's site, the PD2 seems to be discontinued ans the PD1 a regular product).

 

So my questions.

  1. How to drive 16 lights with the RPI 2b according to you (not necessary with PD2)?
  2. What about use the PD2 with a 16 lines mux-demux chip to drive the 16 lights?
  3. How to have multiples daughter board with the 40 pins slot?
  4. Is there a 40 pins Rack like the Pirack for the 26 pins slot?

 

Thank You in advance :-)

  • in reply to chezdomotix

    There are also alternat 16 channel drivers available specifically able to drive LEDs with PWM and up to 85 mA per LED and 28 or more volts so thats an LED of 2W per channel, one big LED or several series LEDs

     

    https://www.google.ca/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=16%20channel%20led%20driver

  • in reply to chezdomotix

    Pretty much any small computer (UNO, PI, etc) will need expansion and the need to have a driver for LEDs or other lights, the same approach can be used for any of them

     

    An UNO will be simpler to start with, Or a MEGA as it wont need additional IO, just a driver for each light. It has more than enough IO lines for your needs.. For a demo you can just drive small LEDS

  • in reply to Robert Peter Oakes

    Thank you Peter :-)

    Yes I can do soldering and will look forward with the chip.

    Maybe the RPI was'nt the good choice, as PiFace seems to be inactive. Maybe rather Arduino ? is there other choice than PiFace for RPI ?

    I tried to plug the PD2 on the PiRack but there are jumpers slots at each end of the 26 pins connectors in the PCB which made the connection, if any, not at best.

    The lights are not chosen yet, this is the artist's work, but i think they will be standards little led lights, maybe colored. We have to discuss this point, and the power supplying too.

    I wanted to proof the concept before ;-)

  • If you're up for a bit of soldering then you can use a chip (Same as used in the PD2), the MCP23S17 that will give you 16 digital outputs (Or Inputs, it will work either way). This is a SPI device and can simply be instructed to drive its outputs as you need. there are plenty of code examples on how to drive the chip

    RPI proto boards are pretty inexpensive and you will only need a few components.

     

    The PI Rack may still work for you as the 40pin PFD2 should still plug into it, you would need to change the address of each board (In the instructions for the board)

    No I have not yet seen a PiRack 40pin.

     

    You dont say what the lights are so I cant say how to drive the load. Please provide this info and I can help some more.

     

    Peter