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Microcontrollers Hit the Airwaves

Want to make your 8-bit microcontroller talk over Wi-Fi like the big kids? Renesas and Redpine may have just the deal for you. The two companies have been collaborating behind the scenes to offer a combination deal of microcontroller-plus-Wi-Fi module designed to get you on the airwaves pronto.

Renesas provides the microcontrollers and Redpine provides the Wi-Fi know-how. Between them, they offer a goodie bag filled with everything you need to make 802.11n Wi-Fi work on an assortment of inexpensive microcontrollers.

Renesas – which was itself formed from the merger of Hitachi’s and Mitsubishi’s semiconductor divisions – now includes NEC as well. The red Renesas logo has turned blue to indicate the change. Redpine (which hasn’t merged with anyone) provides the Wi-Fi expertise.

The combo package comes in three levels of goodness: 8-bit, 32-bit, and 32-bit again. At the 8-bit level, Renesas pairs its R8C microcontrollers with Redpine’s Wi-Fi module, including the requisite firmware. The midrange RX processors offer 32-bit performance at about 100 MHz, again with Redpine modules. At the high end, Renesas offers its SuperH 32-bit RISC processors with – you guessed it – Redpine Wi-Fi modules. Naturally, there are the usual demo/evaluation boards available for cheap so you can experiment before you commit.

Why N?

Paradoxically, 802.11n can be more power-efficient than 802.11b or –g, according to Renesas. How is that possible? After all, 802.11n has faster data rates than 802.11b/g (that’s the whole point), and faster data rates generally equate to more RF energy. Laughing in the face of implacable physics, Renesas think it’s found the answer.

It’s precisely because 802.11n is faster than older Wi-Fi standards that it uses less power. You don’t need to turn the radio on as long, so you can shut off the most power-hungry portion of your Wi-Fi interface between data bursts. Squirting n bits from Point A to Point B takes less time with 802.11n, so you wind up using less energy. The greater speed is just a bonus.

The shorter, faster bursts also pay dividends in a crowded network with lots of chattering clients. Fewer collisions and negotiations mean less airtime wasted in overhead; more airtime spent squirting data.

It’s not a bad deal, and Wi-Fi is certainly an attractive feature for a lot of embedded designers. It’s a difficult interface to design yourself, and even more difficult to get certified. Buying a pre-made and pre-certified module makes good sense. As long as you’re comfortable using Renesas microcontrollers, it’s a quick and easy package. 

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