CIR is generally used to control consumer products such as TVs, DVD players or game consoles with a wireless remote control, but in general can be used for any application that needs to transmit low speed data wirelessly.CIR is a low speed protocol. This means its commands generally contain no more then 32-bits of data with a maximum bit rate of 4000 bits/second (but usually much less). There is no concession for anti-collision, so only one code can be transmitting at any time. Transmission distance depends on the power of the transmitter, and the receiver typically needs to be within line of sight. However, the signal can still reach the receiver without line of sight by bouncing off of the walls and ceilings if the transmitter is strong enough.CIR data is transmitted using a modulated bit stream. Data is encoded in the length of the IR light pulses and the spaces between pulses. The pulses of IR light are themselves modulated at a much higher frequency (usually ~38kHz) in order for the receiver to distinguish CIR data from ambient room light.
A CIR code will often start with a header. This is a pulse and space that immediately precedes the data. Usually the pulse is quite long (several ms), and is used by the receiver to adjust its gain control for the strength of the signal.
Consumer IR, consumer infrared, or CIR is a class of devices employing the infrared portion of the electromagnetic spectrum for wireless communications. CIR ports are commonly found in consumer electronics devices such as television remote controls, PDAs, laptops, and computers.
Since the consumer IR protocols are for the most part not standardized, computers and universal remotes often memorize a bit stream, possibly with compression and possibly without determining the actual bit rate, and play it back. Similarities between remotes are often largely the accidental result of the finite selection of infrared encoder/decoder chips (though now microcontrollers are also used) and IR receiver modules or imitation of the older chips rather than by design. Manufacturers of consumer appliances often reuse the same protocol on many similar devices, though for each manufacturer and device type there are usually multiple protocols in use. The code listings inform about for any universal remote.
Some infrared wireless laptop keyboards and mice use protocols similar to consumer IR devices. Some PC remote controls used for controlling computer media players, controlling presentation software, or other applications also use consumer IR style protocols. Some computer remotes, keyboards, and mice may also use IrDA protocol though IrDA was designed for very short range use.
Sony manufactured a number of consumer devices of different types that share a common proprietary protocol, called S-link. A jack on each device allowed the remote control signals to be interconnected between devices. The protocol included the useful but unusual feature of supporting more than one of the same type of device (such as multiple CD changers). Some AV components could generate informational status codes that could be used to do things like automatically stop your tape deck when the CD you were recording stopped playing. Software running on a PC with a suitable interface could also control the AV components and monitor their activity; for example, your computer could tell what disk and track were playing in your CD changer and look up the titles in one of the internet CD databases. Sony charges 5000 USD for access to the S-Link documentation.Sony use the SIRC protocol for remote controls. SIRC is developed in three different versions: 12 bit, 15 bit and 20 bit. After 12 bits have been received, the receiver waits to see if there are more falling edges to know if the SIRC protocol is 15 bit or 20 bit coded.
Transmission of the IR commands requires only a microcontroller and an infrared LED, available from a wide variety of sources. Reception of the modulated commands for RC-5, RC-6, and the NEC protocols is easily accomplished with specialized IR receivers, most readily available from Sharp Corporation and Vishay Intertechnology. These receivers include a photo-diode, an automatic gain control (AGC) circuit, and a demodulator. The demodulated signal is then decoded with a microcontroller.
Version 3.1 has built-in WiFi (based on ESP8266). It comes with one fully assembled RFToy, OLED display, buttons, 3D printed enclosure, a pair of 433Mhz transmitter-receiver and a pair of 315Mhz transmitter-receiver.
Infrared sampling mode times the duration of infrared pulses and sends the measurements to the computer. It can be used to record and play back most consumer IR remote signals. Many of the recent USB IR Toy applications such as the custom IR Toy WinLIRC plugin and the Record & Play back application. It is suggested to use a recent version of the USB IR Toy firmware for sampling mode. Sending IR signals requires a minimum of USB IR Toy firmware v07.
This is a very small infrared receiver based on the TSOP85 receiver from Vishay. This receiver has all the filtering and 38kHz demodulation built into the unit. Simply point a IR remote at the receiver, hit a button, and you'll see a stream of 1s and 0s out of the data pin.
SE: Has anyone used this with a normal IR LED, driving it at certain frequencies such that this IR receiver can read a string of ones and zeros? I've tried using a 555 timer to make a transmitter. It should work, but without an oscilloscope its impossible to get the frequency right. I've found this site: _control/TX-IR.htm which sells an IC who can drive the circuit on 40khz or 38khz. (edited out, couldn't find view cart button, but its below the add to cart button :-|)
Using some low-cost parts and breakout boards that should only cost around US $10 per demo, two basic demos will be setup. One using IR and one with RF. Each demo has a transmitter and matched receiver attached to mbed. To keep it simple in each case, 8-bit ASCII character data will be sent out over the link and received back using mbed's serial port hardware. A terminal application running on the PC attached to mbed's USB virtual com port will be used to type in test data. The data will only appear back on the PC if the IR or RF communications link is operating correctly. Serial ports use a 10-bit protocol to transfer each character. The idle state of the serial TX pin is high. For bit 1, the start bit, the signal goes low. It is followed by the 8-bits of ASCII character data and a high stop bit (total of 10 bits). The rate at which bits change is called the baud rate. The low cost devices used in the demos will operate at 1200-2400 baud max(or bits per second (BPS) ). For the demo, both the transmitter and receiver are attached to mbed, but in a typical application they would be on different subsystem with its own processor, and physically separated by several meters.IR and RF communication links assembled on a breadboard for the demo.
Consumer IR devices use an infrared LED in the handheld remote and an IR receiver located inside the device. Since sunlight and ambient room lighting would interfere with any IR detector just looking at light levels, the signal modulates (i.e. turns on and off) a high frequency carrier signal. This is called amplitude shift keying(ASK). Typically for IR, the frequency is in the 30-60Khz range with 38Khz being the most common carrier frequency. There are a few early first generation electronic ballasts for fluorescent lights operating this range that can cause interference with IR remotes, but in most cases it works well. This means that the IR LED transmitter must be modulated. On mbed, this can be done using the PWM hardware. The IR detector modules have a built-in bandpass filter and hardware to demodulate and recover the original signal.Sparkfun IR LED transmitter moduleThe Sparkfun IR LED breakout board seen above contains a 50MA high output IR LED and a driver circuit using a transistor as seen in the schematic below. An IR Led can be used instead now that this board is no longer available, but the circuit still needs the correct polarity to control the LED on/off state, since the serial port's internal UART receiver hardware must have a low start bit and a high stop bit to work. A discrete IR LED should have an operating voltage of around 1.5V, so don't forget the series voltage dropping resistor!
Solder header pins into the breakout boards and everything will hookup on a breadboard. Point the IR LED towards the receiver breakout board. At a range of just a few inches the receiver can pickup the signal from the side, if case you have trouble pointing it directly towards the IR LED. Long right angle header pins might be a good idea on these IR breakout boards since they can then be mounted sticking up and directly facing each other. At close range, your hand or a piece of paper will reflect back enough IR to transmit the signal in case you can't mount them facing each other on the breadboard.
IrDA is an infrared communications protocol designed to work at a range of around 1 meter. The IrDA IR signal is not modulated. It relies on high signal strength at a short distance to overcome interference from ambient light. It was a bit more popular in portable devices prior to the introduction of Wi-Fi and Bluetooth. It would require a different IR detector without a band pass filter and demodulator along with software to implement the complex protocols needed for data transfer. IrDA transceiver modules are available in packages similar to the IR receiver used in the demo with data rates from 115KbPS to 4000KbPS. 2b1af7f3a8