IR messaging from roving Bot to another Bot
I have read the Boe Bot Remote Control by IR book but am looking for something less elegant and not bound by the Sony TV protocol. I have an IR buddy but thought there may be some inelegant way to get three bits from point A to B with less expense. What I would like is for a roving Bot to send messages, perhaps 3 bits total for id and the message. The message would indicate working on, success, or failure to achieve a task A fixed positon Bot receiver would scan for messages and act accordingly. I don't see anything indicating this sort of thing has been done but it seems likely it has. Two Bots, each containing its own "active time" timer could be coordinated to operate one after the other and each could communicate to the receiver. I am aware of the restricted directionality of many IR transmitting diodes and IR receivers but that can be dealt with. Any ideas on sources...perhaps I am not using the proper search terms.
Comments
I suspect you probably meant 3 BYTES, as three bits wouldn't be able to hold much information at all. All of the Parallax I/R remote control products use a common protocol, and as you noted, that is the Sony Protocol. You're on your own if you want to create/use something different.
Regards,
Bruce Bates
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Directional IR LED, and simple IR Diode (like the ones that come with BOE)... One on pair each side.
The problems are:
- Need to know then a bit sequence begins
- Need to find sampling rate and pulse rate
- Need to make sure BOE doesn't pick up the IR reflections from it's own LED, and get confused.
To date I assembled a 555 timer to produce a 38kHz square wave output that was fed to an IR led. This is detetected quite successfully with the Panasonic IR photo detector that is sold through Parallax. I used it with two detectors to guide the Boe Bot while holding the timer/led circuit in my hand. I am thinking of having the BS2 turn the timer output on and off as needed to generate the start pulse and the PWM pulses for the message. These would have longer on and off times than the 0.6 mSec that is the basic unit of time measure for Sony. Their times are so short that some work arounds have to be used (RCTIME instead of PULSIN) to detect the presence of the "0" (0.6 mSec on) and the presence of the "1" (1.2 mSec on). The difficulty is that the off time is only 0.6 mSec and that is not enough time for the BS2 to do what it has to do before returning to the next data bit.
Perhaps I will just modify the Sony protocol by lengthening the 0.6 mSec basic time measure to 2 mSec or so according to the needs of the BS2.
More than one remote Boe Bot transmitting at a time would be a problem for the receiver. A more robust method would be for the Master to interrogate and only upon interrogation would a remote send information.
The beam width of the Farchild IR diodes I have is +/- 10 degrees. Shine an led flashlight on a wall and one gets an idea of how narrow these beams can be. This way they get a modestly high radiated power density with modest input power. An omnidirectional radiator will require proportionally more input power to achieve the same radiated power density, which is what the receiver cares about.
I have considered lenses that will re-direct the narrow beam into one that is uniform for 360 degrees of azimuth but is restricted in vertical elevation, like a navigational light for a waterway. Perhaps I should see what Edmund Scientific has in the way of lenses and sources.
http://roboflag.carleton.ca/resources/technical/ir_beacon.shtml
I also read that using a ball bearing above the ir transmitter(pointed up) could possibly be used as a reflector....
-M
The ball bearing is a nice idea, I recall the disco balls, there may be some parallels.