Aaaaargh - bad-day day. I'll re-post when I've got my head fully working.
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Okay, third attempt after a brisk walk in some fresh air.
Thanks to xstamp's reminder, there's an easy way to use an 08M as a self-modulating IR transmitter ...
http://www.rev-ed.co.uk/picaxe/forum/topic.asp?topic_id=6363
What we don't have is an easy means to create a 555 replacement, IR modulator for a PC serial stream without additional components. Polling the PC serial line to modulate within the 08M is just too slow. This could be overcome if an IOLOOP command were added which executed an equivalent to 'pin0 = pin4' command every few uS forever ...
<code><pre><font size=2 face='Courier'> PICAXE-08M
.----------. 180
-| +V 0V |- ___
___ -| SI O0 |---|___|----.
PC TX >--.----|___|--->| X4 X1 |- _|_ -->
.|. 22K -| I3 X2 |---. _\./_ --> IR
| | `----------' | | -->
|_| 10K `--------'
|
0V --^-- </font></pre></code> Such a simple command could hopefully be shoe-horned into an 08M, and would IMO be a very useful addition, allowing the 08M to be used as a PC serial / 'TTL' to IR modulator, complimenting the demodulating function of the TSOP18.
Additional 'modulation enabling' from other PICAXE's can achieved by letting Pin 4 float or by clamping it to 0V to disable.
<i>Why not use a cheaper 555 ? </i>
It's not that cheap when you don't have one and need to add P&P. It also needs additional components, fingers crossed tightly that it runs at 38kHz, and little hope of debugging the signal without a scope.
<i>Why not use additional logic gates ? </i>
Additional logic to modulate PC serial also means additional clamping diodes, draws more current, and needs a larger footprint.
In these days of Energy Footprints and Carbon Costs, less is better should be the name of the game. A few bytes of code added in PICAXE firmware makes small but useful savings elsewhere -- "PICAXE saves the Planet. Read all about it !"
<i>Will this work with a 38kHz PWMOUT and a ~8uS IOLOOP sampling rate ? </i>
Good question. I have no idea. A proper IRMOD command which generates IR PWM on Pin 0 when an Input is high would be better, but would take up more firmware space.
Edited by - hippy on 10/03/2007 14:59:24
---
Okay, third attempt after a brisk walk in some fresh air.
Thanks to xstamp's reminder, there's an easy way to use an 08M as a self-modulating IR transmitter ...
http://www.rev-ed.co.uk/picaxe/forum/topic.asp?topic_id=6363
What we don't have is an easy means to create a 555 replacement, IR modulator for a PC serial stream without additional components. Polling the PC serial line to modulate within the 08M is just too slow. This could be overcome if an IOLOOP command were added which executed an equivalent to 'pin0 = pin4' command every few uS forever ...
<code><pre><font size=2 face='Courier'> PICAXE-08M
.----------. 180
-| +V 0V |- ___
___ -| SI O0 |---|___|----.
PC TX >--.----|___|--->| X4 X1 |- _|_ -->
.|. 22K -| I3 X2 |---. _\./_ --> IR
| | `----------' | | -->
|_| 10K `--------'
|
0V --^-- </font></pre></code> Such a simple command could hopefully be shoe-horned into an 08M, and would IMO be a very useful addition, allowing the 08M to be used as a PC serial / 'TTL' to IR modulator, complimenting the demodulating function of the TSOP18.
Additional 'modulation enabling' from other PICAXE's can achieved by letting Pin 4 float or by clamping it to 0V to disable.
<i>Why not use a cheaper 555 ? </i>
It's not that cheap when you don't have one and need to add P&P. It also needs additional components, fingers crossed tightly that it runs at 38kHz, and little hope of debugging the signal without a scope.
<i>Why not use additional logic gates ? </i>
Additional logic to modulate PC serial also means additional clamping diodes, draws more current, and needs a larger footprint.
In these days of Energy Footprints and Carbon Costs, less is better should be the name of the game. A few bytes of code added in PICAXE firmware makes small but useful savings elsewhere -- "PICAXE saves the Planet. Read all about it !"
<i>Will this work with a 38kHz PWMOUT and a ~8uS IOLOOP sampling rate ? </i>
Good question. I have no idea. A proper IRMOD command which generates IR PWM on Pin 0 when an Input is high would be better, but would take up more firmware space.
Edited by - hippy on 10/03/2007 14:59:24