[simpits-tech] Who is using a Centipede shield to drive their LED's ?

[Matt Bailey]

On Thu, 21 Nov 2013 19:24:40 -0800 (PST)
geneb <geneb at deltasoft.com> wrote:

> On Thu, 21 Nov 2013, Matt Bailey wrote:
> 
> > I used a couple of these stacked on an Uno to read all the analog
> > radios (including the old-style dial ADF tuner) in a 737 cockpit.
> > Works a treat. :)
> >
> I haven't tried them for inputs yet.  I take it they do a good job?

They're perfect. I just set all the channels to "high" which enables
the built-in pull-up resistors, so all I have to do circuit-wise is
connect my switches or other inputs to ground...no diode matrices or
pull-up/down resistors in my circuits (of course, you could always
disable any or all of the pull-up resistors if you needed to use
pull-down resistors in your own circuits). The library they have
written just gets copied into the folder with the rest of your Arduino
IDE stuff and handles reading/writing the addresses of each register on
the board(s) (via the address of the board itself, which can be set
with a jumper to allow stacking two of them on top of an Uno). Their
code abstracts all this out to calls that mimic the digitalRead() and
digitalWrite() functions of the stock Arduino library....the board
basically "looks" like an Arduino with 64 (or 128) I/O pins. :)


> Right now the only thing I'm using the Centipede for is to drive my
> 16 channel high-power boards.  I've got five built out of the eight
> I'll eventually need.  Because of how the driver boards work, the
> Centipede only sees a light load - only enough to bias the TIP-125
> into switching on.  There's no problem at all in using a whole
> Centipede for outputs, just as long as you're using a driver board.
> I would NOT use my driver board to drive relays or motors however.
> There's no back-EMF protection in the circuit so you'll likely blow a
> driver transistor the first few times it's used that way.  That being
> said, there's no reason why you can't create a tiny little board to
> handle those cases where you need to do that kind of switching.

Cool! Actually I have not looked at your board layout yet, as my laptop
doesn't have a 7Zip extractor installed apparently, so I wasn't sure on
the magnetic protection. That's not hard to handle though, I will
probably use your board as a starting point and tweak it for what
mechanical loads I have. I for sure will be driving the Sabreliner's
stall shakers, and probably some surplus autopilot servos for, well,
the autopilot (connected directly to the pitch/roll pushrods). I may
possibly be controlling hydraulic pumps and actuators in the control
loading system as well.

I guess the next thing I will need to work on is a massive PWM board. I
plan on interfacing all the D'Arsonval-based gauges in the cockpit, and
I need 2 PWM outputs for each air core instrument I end up doing. Then
there is the synchro issue....if I figure out how to directly control
synchros with the Arduino, I will probably need a lot more PWM channels!

Matt