In this series of How To I shall emulate a IR remote control using a Texas Instruments Launchpad MSP-430G2 and few discreet components. The exercise was undertaken by me purely as a self learning exercise.
Before I proceed to the coding basics , I would like to introduce readers to the RC6 protocol and its variant 6-20. The users may ask where is this protocol used, the answer may be in your own house. The IR controller of Tata Sky (DTH service provider in India) and Sky HD in Europe DTH STBs employ the protocol.
Understanding the RC6 Protocol. RC6 protocol is a derivative of the ubiquitous RC5 protocol developed by Philips. The RC5 protocol is extremely simple, at the same time robust and very well documented. RC6 protocol on the other hand is sparsely documented and its implementation varies from one manufacturer to another. That’s extremely surprising considering its impressive pedigree. Before I go ahead, readers may be eager to know how the waveform actually looks. A partial scope-grab of such a transmission is shown below
At a first glance, it appears as a normal set of pulses differing in width and temporal separation. But then why is the pulse area shaded? Zooming in to the waveform (decreasing the time base of the scope) we can observe that each of the pulse actually consists of a set of pulses with period of silence between them. These series of pulses which are switched on and off comprise the carrier of the transmitted signal.