Re: gEDA-user: FIRST robotics...

[DJ Delorie <dj@xxxxxxxxxxx>]

> I also want to have a simple kit for them to do a manual
> servo/Victor controller that they can use next year to test servo
> and motor drive parts without having the whole robot powered up or
> the main software running. I am planning on using an ATTiny24 to
> read 2 1-turn pots and an analog joystick to generate 4 PWM
> outputs. Do you have LEDs for both directions on every channel? That
> would push the pin out to 16, and require the next larger ATTiny, or
> maybe even an ATMega to handle that many LEDs, along with 4 analog
> inputs and 4 PWM outputs.

I'm using an R8C/1b (pillar's adapter, amusingly enough) which has 20
pins.  It controls one servo (if we need more, we use the computer),
so it has one ADC input from the potentiometer, one timer output
(conveniently, it's connected in hardware, not software) and the rest
of the pins (11) are connected to LEDs.  The center LED is yellow, all
red on the left, all green on the right.  This corresponds to the
Jaguar status LED.

Alternately, use a single red/green LED for each channel, with two
pins per LED.  I use a PWM-like algorithm to programmatically dim the
LEDs anyway, so you can smoothly transition from red to yellow to
green, or blink them like the speed controllers do.  Still four pins
per channel, though.  Check into the 32-pin R8C's - they're $5-7 each
but have built-in three phase motor control, which gives you a bunch
of PWM outputs to play with.


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