Newbie - Minimum necessary to control RC servo & 1 relay

Hello,

What is the minimum necessary to receive and decode IR serial data
from PC serial port, and then control an RC servo and 1 relay?
Quickbasic is used to send data. I just started looking into
microcontrollers but haven't purchased one yet. Parallax starter kit
looks attractive but seems rather pricey for what I want to
accomplish.

Ben

--

 

You may want to check the comp.robotics.misc news groups for
similar setups. I don't understand how you are sending IR through
a serial port, but a simple way to control servos from a computer
via the serial port is to use a programmed servo control chip. At
the link below I show how I use the ezservo chip from kronos
robotics ($6.95) to control servos that operate a pan and tilt
webcam. The bottom link shows a workaround I made to control some
LEDs using the servo control output lines from the chip. This
could control a relay if desired.

http://www.geocities.com/zoomkat/ezservo.htm
http://www.geocities.com/zoomkat/ezservo1.htm
http://www.geocities.com/zoomkat/ezservo-led.htm

 

shb*NO*SPAM*@comporium.net (Si Ballenger) wrote in

I meant a PC serial port connected to an IR transmitter.

Thanks. That is just what I was looking for. I thought there'd be a
chip for that app.

Where's the circuit that converts a servo output to an on-off output?

Ben

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For the LED I put a diode and a 1k resistor in series from a
servo output pin to the base of an NPN transistor. Between the
diode and the resistor, I put a .1mf capacitor connected to
ground. There are sufficient pulses for the servo (chip set for
its longest pulse lenth on the pin) to charge up the capicator
and supply a ~steady current to the transistor base. The LED is
connected to a power supply and is in series with the transistor
collector/emitter. A driver chip that needs less current to turn
on might work better than just a NPN transistor in this setup.
YMMV.