Propeller Sequencer Help

CaliforniaKids

I am trying to build a basic sequencer. I would like to ripple a high output through 20 output pins. The time duration could be about .5 seconds dwell at each pin before moving on. It could loop forever. It would start when it received an input trigger and stop when it received a pulse on another input pin. I would like to remotely control it from about 50 feet away: Ethernet, USB I2C, RS 232, wireless? Any suggestions?

Thanks, CK

groggory

For the sequencing stuff, that could be done within your first attempt at the prop education kit. Piece of cake. Single cog in a loop doing the sequencing

For the remote control you could do it with Xbee using the I/O pins (through the obex xbee object). ~$20/xbee

or you could go simpler and cheaper and use something from linx wireless. LC series transmitter & receiver. Then throw on a 'splatch' antenna or 1/4 wave whip or JJB antenna. ~<$4/ radio + <$3/ antenna

or http://www.sparkfun.com/products/691

JonnyMac

This is very easy -- the code below will give you an idea of starting and stopping a sequencer cog. The cog also monitors a global variable called hold so that you can hold and resume the sequence if desired.

This is NOT a full program, just demo code to help you get up and running

pub startseq

  hold := false
  cog := cognew(sequencer, @stack)


pub stopseq

  if cog
    hold := true
    cogstop(cog~ - 1)


pub holdseq

  hold := true


pub resumeseq

  hold := false


pri sequencer | t, idx

  t := cnt                                                      ' sync timing
  repeat
    repeat idx from 0 to 19                                     ' loop through pins
      outa[19..0] := 0                                          ' clear last
      repeat while (hold == true)                               ' if in hold mode
        t := cnt                                                '   resync timing
      outa[idx] := 1                                            ' output/high
      dira[idx] := 1
      waitcnt(t += clkfreq/2)                                   ' wait 1/2 second

groggory

JonnyMac wrote: »

This is very easy -- the code below will give you an idea of starting and stopping a sequencer cog. The cog also monitors a global variable called hold so that you can hold and resume the sequence if desired.

This is NOT a full program, just demo code to help you get up and running

pub startseq

  hold := false
  cog := cognew(sequencer, @stack)


pub stopseq

  if cog
    hold := true
    cogstop(cog~ - 1)


pub holdseq

  hold := true


pub resumeseq

  hold := false


pri sequencer | t, idx

  t := cnt                                                      ' sync timing
  repeat
    repeat idx from 0 to 19                                     ' loop through pins
      outa[19..0] := 0                                          ' clear last
      repeat while (hold == true)                               ' if in hold mode
        t := cnt                                                '   resync timing
      outa[idx] := 1                                            ' output/high
      dira[idx] := 1
      waitcnt(t += clkfreq/2)                                   ' wait 1/2 second

Also, if you need some precision note that flipping a pin high or taking it low takes about 6 microseconds when you're running the prop at 80 MHz (according to my logic analyzer)

JonnyMac

could be about .5 seconds dwell at each pin

...was a clue that this could be handled in Spin. It would be nearly as easy in PASM, though.

groggory

JonnyMac wrote: »

...was a clue that this could be handled in Spin. It would be nearly as easy in PASM, though.

Wow, talk about an easy app.

Might as well just run the prop at 20kHz off the internal oscillator and save some batteries too. :-)

JonnyMac

If he uses contact closure inputs, absolutely.

Cluso99

You could also use a set of serial latches which would require 3 pins (clock, data, reset) plus of course power/gnd. For 50ft, it really depends on what the environment is like - you may require rs232 or rs422/485 or straight prop to latches may work.

So, it really depends on your app. The pasm code to run this is extremely simple.