Infrared, IR, Communications technology is used to link consumer equipment such as a remote control with a television since the late 1970’s. Over the years manufacturers have developed a multitude of digital communication protocols most commonly based on Amplitude Shift Keying, ASK, modulation. The introduction of new protocols differentiated communication schemes, im-proved robustness, and optimized data transmission capability. As IR communication protocols matured, companies developed competing IC solutions tailored to fit OEM remote controls, univer-sal remotes, and computer based hardware. However, specialized hardware solutions for mobile devices are conspicuously missing from this list… until now.
Flash forward to the era of mobile devices; the technology of IR communications has virtually remained unchanged. However, in living rooms around the world, an increasing number of televi-sion watchers are sidelining OEM remotes in favor of smartphones equipped with “IR Blasters”. A multitude of companies have remote control Apps that do much more than just change the televi-sion channel. Some Apps have features that suggest programming to users, signal users when favorite shows are about start, automatically change the channel, and present individualized adver-tising content. Sadly, these intriguing features will not continue to be available because manufac-turers simply can’t afford the monetary cost or the printed circuit board space using traditional IC solutions. Manufacturers are only willing to offer IR Blaster features if the IC costs less, is smaller, requires less power, drops in to the hardware architecture, and integrates seamlessly with the sys-tem software. Happily, ams has developed new hardware technology called IR-BeamTM which is tailor made solution to integrate IR communication in mobile device applications.
Existing IR Blaster integrated circuit solutions are no longer a good fit for mobile devices. This leaves cell phone and tablet manufacturers to weigh options and make tradeoffs. As with all con-sumer technology, the scale is tipped as semiconductor solutions become smaller, cheaper, and easier to integrate. The inclusion of IR remote control into mobile devices is no exception. Long standing IR solutions use dedicated/specialized 8/16-bit microprocessors, FPGAs or ASIC – none of which are well suited for mobile devices. Such solutions may be cost prohibitive, physically too large, unable to support certain IR protocols, difficult to integrate into system hardware, lack soft-ware drivers, or may simply consume too much power.
Despite being ill-suited, an FPGA with 4kB RAM along with discrete MOSFET driver and 940nm LED is the current solution of choice in smartphones. Operating as a FIFO, pattern data originating from the Application Processor, AP, is buffered, mixed with a carrier frequency, and output to an external IR LED circuit. IR communication using FPGAs are a well proven technology but many manufacturers are designing them out of mobile devices. Current FPGA technology has a mixture of advantages and disadvantages in mobile applications. Since the FPGA is re-configurable, HDL code can be quickly written and debugged reducing time to market. Furthermore, FPGA manufac-turers offer reference designs to assist OEM in development. Package size can be as small: ≥7 mm2, however larger footprints are more common1. Disadvantages include high monetary cost and high static power consumption ( ≥75uA). Additionally, OEMs would have to design and maintain an additional HDL codebase.
Note 1: Smartphones which use an FPGA for remote control pattern generation may also incorporate other functions and features, resulting in the need for a more powerful FPGA and larger footprint.