IR Repeater

This Project was submitted to Parallax by Stephen Wagner.
A custom IR remote repeater with IR signal and IR protocol modification capabilities

Almost all consumer electronic entertainment products available today can be and in most case must be controlled, programmed and adjusted with a remote control device utilizing IR technology. My parents are in there mid 70’s and have a small LCD television and satellite receiver in there bed room, both of which are controlled by individual IR remote controls. As you can imagine trying to watch television with multiple remote controls, old school thoughts and new technologies can be very confusing, difficult and frustrating.

The remote provided with the television they own is application specific for that television and has no universal/programming/learning capabilities. The remote provided with the satellite receiver they own is a universal remote capable of controlling many brands of consumer entertainment electronic products. Unfortunately the remote provided with the satellite receiver will not control their inexpensive television. In an attempt to control the satellite receiver and television with one remote and minimize the confusion, difficulties and frustrations associated with two remotes, I purchased a universal remoter control from another big box retailer. The new universal remote did control the satellite receiver, however, it would not control the inexpensive television.

There must be a simple turnkey solution to control the satellite receiver and inexpensive television with one IR remote control simultaneously. An IR repeater with IR signal and IR protocol modification capabilities would be necessary to control the inexpensive television with the satellite receivers IR remote control.

Utilizing the Parallax papers, IR Remote For The Boe-Bot and Understanding Signals, a Parallax OEM BASIC Stamp module, IR receiver, miscellaneous hardware and research off the internet, I reversed engineered the IR signals from the satellites remote control default settings and the inexpensive televisions remote control. The IR signals emitted from the satellite receivers remote did follow a standard IR protocol; however the IR signals emitted from the inexpensive television remote did not follow a standard IR protocol, which explains why the inexpensive television would not respond to IR signals from a universal remote.An IR receiver (the OEM BASIC Stamp module), an IR emitter, a regulated 5Volt wall wart and miscellaneous hardware make-up the custom IR repeater. Both the IR receiver and emitter are configured to receive IR signals from and transmit modified IR signals to the television viewer/operator. The IR signal emitted by the custom repeater reflects off the wall(s) and is received by their inexpensive television. This configuration provides the consumer/viewer/operator with a simple un-intrusive turnkey solution. Place the repeater in the vicinity of the inexpensive television/satellite receiver with the IR receiver and emitter facing the viewer/operator, plug in the wall wart and enjoy.Utilizing parts of the code provided in the IR Remote For The Boe-Bot paper, the OEM stamp receives and processes IR signals from the satellite receivers universal remote and responds only to the following four (4) default commands: 1. POWER; 2. (+) VOLUME; 3. (-) VOLUME; 4. MUTE. When one of above four (4) commands are received and processed by the OEM stamp, the OEM stamp and the IR emitter transmits the necessary IR signal(s)/protocols to operate the inexpensive television.

When the POWER button is pressed on the remote, both the satellite receiver, and inexpensive television responds and turns on and/or off. When the channel up/down and or numeric buttons are pressed on the remote, only the satellite receiver responds. When the (+/-) Volume and/or Mute buttons are pressed, only the television responds.

My parents can now enjoy watching television with the luxury of just one remote thanks to the papers presented and the products available from Parallax.

Appendix:

Satellite Receiver IR Remote Protocol -
Synchronization, 6 bits of custom code, 6 bits of command code, 6 bits of inverted custom code and 6 bits of inverted command code, LSB first, for a total of 24 bits plus synchronization and stop burst.
Synchronization timing: 4000uSec burst, 4000uSec off
Binary “0” timing: 870uSec burst, 870uSec off. (1740uSec)
Binary “1” timing: 870uSec burst, 2610uSec off. (3480uSec)
Stop burst: 870uSec burst.
Custom Code: 15
Power: 21
Default TV Codes
Custom Code: 14
(+) Volume: 61
(-) Volume: 29
Mute: 63

Inexpensive Television Receiver IR Remote Protocol -
Synchronization, 8 bits of custom code, 8 bits of inverted custom code, 8 bits of command code, 8 bits of inverted command code, LSB first, for a total of 32 bits plus synchronization and stop burst.
Synchronization timing: 9000uSec burst, 4500uSec off.
Binary “0” timing: 560uSec Burst, 565uSec off. (1125uSec)
Binary “1” timing: 560uSec Burst, 1690uSec off. (2250uSec)
Stop Burst: 560uSec Burst.

Notes: 1. The 8 bits of custom code for the inexpensive television is all zeros “0” and the 8 bits of inverted custom code is 189 or 10111101. This protocol follows no standard IR protocol. 2. The stamp can only perform a minimum 572uSec burst followed by a 553uSec or a 1678uSec off. 1250uSec or 2250uSec total. The inexpensive television tolerates the +/-12uSec differences.

Custom Code: 0
Inverted Custom Code: 189
Power: 1
(+) Volume: 12
(-) Volume: 16
Mute: 4

Application / Installed View and Hardware Views

PBasic source code:
Note: 1. The stamp code for this repeater was generated prior to fully understanding the IR protocols involved; 2. In an effort for the inexpensive television to respond to the IR commands, a one (1) second delay is necessary from the time when the IR signal is received and processed by the OEM stamp to the time when the modified IR signal is transmitted. This is necessary to allow time for the IR receiver AGC processing/circuits to settle within the inexpensive television after attempting to process and rejecting the unmodified IR signal first transmitted from the handheld IR remote.