View Full Version : BS2 to BS2 IR messages, minimizing data errors

01-26-2007, 08:04 AM
I have been using the IR receiver with a Boe Bot (BS2) to receive IR transmissions from the Parallax remote control.· All is well with the exception of occasional noise which comes from the receiver.· When I monitor the receiver output with an oscilloscope it is evident that the receiver often puts out a "0" when I am not transmitting (in a room with flourescent lights).

Also, I have had one BS2 send a 4bit message to anoher via an IR link.· (The timing is SonyTV-like but it follows Appendix B in the book "IR·Remote for the Boe Bot".· ·Most of the time the message comes through fine but some messages are wrong, particularly for larger distances.· I blame noise in the receiver.

My question is how can I improve the reliability of the received message?· Send·7 bits and a parity bit?· Insist that the receiver send the transmitter the message to confirm?· Other coding?

Finally, I·once used a 555 timer, controlled by the transmitter·Bot, to produce the 38.5 kHz IR signal·· This·would produce good·intensity·IR at 38.5 kHz with less signal at the odd harmonics.· However, the BS2 Freqout command produces·aproximately the same·signal at about 27KHz as·it does at·38.5 kHz.· Other than using smaller resistors to increase the current through the transmitting diode, is there any way to increase the range of the IR communication system when using the Freqout command?

Thanks for any ideas.

01-26-2007, 08:12 AM
Try to shield the receiver from room lights and sunlight as much as possible.
Use a IR LED with higher output, or use a transistor and multiple IR LED.
Use a slower baud rate.
Send the code multiple times and have the receiver screen the received bytes.
Use a correcting algorithm (like Hamming or SECDED).


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Post Edited (Bean (Hitt Consulting)) : 1/26/2007 1:17:39 AM GMT