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8-bit RISC MCU with crypto runs at 1.6V

Atmel’s XMEGA is an addition to its AVR RISC family of microcontrollers it designed, the company says, with a focus on overall system performance in the 8/16-bit market sector. Continuing the family theme of 8-bit designs architected specifically for Cprogramming, the chip offers “true 1.6V operation” at low power levels. Flash-memory- based, it hosts 12-bit analogue functions, a DMA controller, a cryptographyfunction engine and an architectural feature that Atmel calls Event System.

By “true 1.6V operation”, Atmel means that all functions such as fl ash-memory reprogramming, EEPROM writes, analogue conversions and internal oscillators will run at that voltage level. In powerdown mode with RAM contents preserved, current consumption is 100 nA, and a real-time clock running from a 32-kHz crystal adds 650 nA. The Event System is a structure that communicates directly between peripherals without intervention by either CPU or DMA; Atmel says its benefi ts are fully deterministic operation and short response times, as well as lower power when the CPU does not need to be awakened. Any peripheral can signal an event— which is anything that will generate an interrupt—to any other peripheral, via a large multiplexer structure; you can use the CPU to set up an event channel, which is then “locked” and continues to exist without further intervention by the CPU. Your system can then respond to any defi ned condition rather than a simple signal such as a clock event: for example, when controlling an analogue level, you might set a measured level to trip an alarm or switch off some controlled parameter. This would then continue to operate as a safety limit independent of the CPU and in addition to any software-controlled routines that were running there. It removes bottlenecks associated with multiple, frequent or overlapping trigger events or interrupts; there is no software overhead and the system handles critical tasks with a guaranteed latency less than the interrupt response time.

The hardware crypto engine supports AES and DES algorithms and is, Atmel says, the only high-bandwidth—up to 2 Mbit/sec—product available for long-battery-life applications such as road-toll tags.

Microcontrollers in the range span 16 to 384 kbytes of fl ash memory, in 44- to 100-pin packages, operate from 1.6 to 3.6V, and run at up to 32 MHz. As RISC devices this means a MIPS rating of 32, but Atmel says that due to the Event System’s ability to relieve the CPU of processing load, you will get more throughput than 32 MIPS might indicate in other architectures. The core itself is a lower-power version of previous AVR CPUs and offers compatibility at a hex level, preserving memory locations for re-used code. The fi rst devices in the family have 128 or 64 kbytes of fl ash and cost $3.75 or $3.50 (10,000).

Atmel, www.atmel.com.