Cirrus-ly powerful chips boost Windows Media Audio
Published: 29 Sep 1999 11:17 BST
Tuesday's joint announcement by Microsoft and Cirrus Logic to further develop next-generation portable music devices will inevitably fuel more debate into the benefits of Windows Media Audio (WMA) over the more pervasive MP3 format.
But it is Cirrus' development of the Maverick System-on-Chip (SOC) silicon that is the real marvel of the initiative. A deceptively small processing engine, the Maverick promises to combine nth-degree integration with Pentium 100MHz-level performance to turbo-charge the next wave of handheld audio players.
Cirrus re-wrote the processing rulebook with its strategy of developing market-specific chips. But exactly how has it managed to squeeze so much performance out of its latest flagship audio SOCs?
The company is developing three new Maverick SOCs, the EP7209, EP7211 and EP7212, consistent with Cirrus' strategy of developing Market Specific Processors (MSPs).
- The EP7209 is a complete integrated SOC for digital audio decoding, designed specifically for implementing audio-processing algorithms in applications where power consumption is a concern. As with other chips in the EP7200 range, it is built around an ARM720T embedded processor. It also includes a 32-bit real-time clock and a range of integrated peripherals, such as an LCD display controller, an audio DAC interface, and a flash memory interface. OEMs can take this chip and build a portable audio decoder by adding an LCD display, audio DAC, and a flash memory sub-system. It uses a 32-bit RISC processing engine to implement decompression algorithms and is a full ISO-compliant MPEG 1,2 and 2.5 layer 3 audio compression engine within 50 percent of its available processing power.
- In contrast, the EP7211 has been designed from the ground up as a more general power-house for high-performance, ultra-low-power applications such as PDAs, pagers or smart phones. Once again the core is an ARM720T with 8Kbytes of four-way set-associative unified cache and a write buffer. Windows CE support is provided with an enhanced memory management unit (MMU). The system board can be completed by just adding memory and peripherals. All interface logic is integrated on the chip. The EP7211 is available in a 208-pin LQFP or a new 256-lead PBGA package.
- The very latest Maverick, the EP7212 SOC, is specifically optimised for Internet audio and is capable of supporting multiple audio standards, including the ubiquitous MP3 and Microsoft's Windows Media Audio upstart.
Again it uses a ARM 720T microprocessor core with an internal clock-speed ranging from 18 to 74MHz at 2.5 volts. With MP3 decoding using less than 45MHz, the chips remaining power can be left over for additional functions.
This is the Pentium 100MHz performance mentioned above. Unlike the Pentium, however, the ARM-based system design (under 90 milliwatts at 74MHz or ten microwatts in standby) results in the long battery life necessary for handhelds. The SOC has in-built LCD support, PC connectivity and flash memory.
The EP7212 comes in the same formats as the EP7211, and will ship in quantity towards the end of the year, for as low as £15.95 in quantity, or $1495 (£927) for a complete development board.
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