JVC also has its own IR protocol, although I have seen several different protocols being used in a diversity of JVC equipment. This is probably the case for equipment which JVC haven't made themselves. Most genuine JVC equipment is controlled by the protocol described on this page though.
All information about this protocol was collected using a JVC PTU94023B service remote control and a digital storage oscilloscope.
The ITT IR protocol is a very old one. It differs from other protocols in that it does not use a modulated carrier frequency to send the IR messages. A single command is transmitted by a total of 14 pulses with a width of 10µs each. The command is encoded by varying the distance between the pulses.
This protocol used to be very reliable and consumes very little power ensuring long battery life. One big disadvantage of this old protocol is that it sometimes triggers false commands, for instance when you put a laptop computer with an active IRDA port close to the IR receiver.
Many consumer electronics brands used this protocol in Europe. Among them were: ITT, Greatz, Schaub-Lorenz, Finlux, Luxor, Salora, Oceanic and later also Nokia, to name but a few.
This article will use one digital input pin (PortA pin 3) to readout state of push-button connected to it. Pull-up resistor must be connected to this pin to differentiate voltage on pin when push-button is pressed and when it is released. In short period of time when push-button is pressed, voltage on input pin connected to is very noisy and this can make problems. This is shown on picture on left side. Microcontroller would interpret this as multiple push-button pressing and releasing. To eliminate this we use debouncing.
All 1-Wire® devices, including iButton® devices, contain an 8-byte unique registration number in read-only memory (ROM). This registration number is used as a unique network address on a 1-Wire bus. To ensure data communication integrity, one byte of each registration number is a DOW CRC byte. This article explains how to calculate this 8-bit DOW CRC and gives example code that is used in iButton AVR readout example project used with DS1990R-F5.