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Re: Mobile Sensorium [was Re: Time for Serious GPS Application]

From: Doug Sutherland <>
Date: Sat, 6 Jan 2001 19:27:52 -0800

Matt Carlson wrote:

> Right.. all I'm really talking about is sending these codes.

I didn't think that the IrDA transceivers on the Visor
would be compatible with the radio shack IR decoder 
(which is actually a Sharp GP1U52X), but ...

> I've seen several programs for the PalmOS that allow 
> you to use the IR port as a universal remote. 

Interesting, I didn't think that was possible. They 
must be modulating at the same frequency (~38kHz) and
filtering out the same ranges. If that's the case 
then perhaps you can make it work. This much I know:
the GP1U52X IR Decoder rejects all sources outside
of 40Khz +/- 4Khz, it connects to the microcontroller
at 893 baud, 8 data bits, 1 stop bit, no parity. The
IR remote control that I use has to be set to TV code
#21 to work with the GP1U52X. And when I press the 
buttons on the remote I receive these codes through 
the IR decoder:

  Volume Up     153
  Volume Down   157
  Channel Up    145
  Channel Down  149
  Mute          137
  Number 1      217
  Number 2      253 
  Number 3      249
  Number 4      245
  Number 5      241
  Number 6      237
  Number 7      233
  Number 8      229
  Number 9      225
  Number 0      221

A quick test would be to attach power and ground to the 
GP1U52X IR Decoder, and attach the output pin to one of 
the ports on the microcontroller. Then open up that pin
at 893 baud 8N1, start listening for incoming  bytes, 
and send the above codes from the Visor. 

> From what I've seen I think my idea is possible.. if 
> not I'll learn some more and do it again :)

That's the only way: build, tear down, and rebuild.
Last night I figured out how to switch on and off 
power to my GPS receiver using 5 volt relays from 
radio shack. I learned that a transistor is needed
because the BX24 doesn't have enough output power
to activate the relay coil. But putting a single 
transitor between the microcontroller output pin 
and the relay coil works like a charm. I will soon
have a bank of relays switching power to the LCD
display, GPS receiver, and also the auxilliary 
sensor microcontrollers. 

There is some very useful and relevant info here:

http://support.tandy.com/support_supplies/doc3/3313.gif
http://support.tandy.com/support_supplies/doc3/3313002.gif
http://www.sharp.co.jp/ecg/unit/unit.html

Here's an interesting twist on using these:
http://www.mil.ufl.edu/imdl/handouts/sharphack.pdf

And once again this is a great launching point for 
learning more about how they work and getting tips
for building circuits etc.

http://www.us-epanorama.net/irremote.html

  -- Doug

------------------------------------------------------------
  Grow your own Wearables: http://wearables.los-gatos.net
 What I'd like is to have you call me and my jacket answers
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