12 December 2006

Atmel ARM9-Based MCUs Increase Internal Data Bandwidth

Atmel has shown off the latest member of the SAM9 family, the AT91SAM9263 embedding a 200 MIPS ARM926EJ-S-based microcontroller that overcomes possible bottlenecks that occur with conventional ARM9-based MCUs in graphically- interfaced, data-intensive applications such as networked medical monitoring equipment and GPS navigation systems.

The AT91SAM9263 employs 27 DMA channels including Atmel's 18-channel peripheral DMA controller (PDC), a 9-layer bus matrix, and two additional busses for data and instruction-tightly-coupled- memories (TCMs) to boost CPU performance and provide on-chip data transfer rates of up to 41.6 Gbps. Two external bus interfaces (EBIs) support gigabyte- plus external memories.

On-chip human interface peripherals include a camera interface, TFT/STN LCD controller, a 6-channel audio front-end interface (AC97), I2S and a 2D graphics co-processor that off-loads line draw, block transfer, polygon fill, and clipping functions from the CPU.

Networking peripherals include a 12 Mbps USB host and device, a 10/100 Ethernet MAC and a 1 Mbps control area network (CAN). There are also four USARTs, two 50 Mbps serial parallel interfaces (SPI), CompactFlash, SDIO (MCI) and a two-wire interface (TWI) which can be connected to external wired and wireless communication modules like GPRS modem and Wi-Fi.

Conventional ARM9-based processors use load/store instructions that require at least 80 CPU cycles to transfer a single byte of data between memory and a peripheral. Running at 200 MHz with a bus frequency of 100 MHz, these processors typically reach the limit of their capability at about 20 Mbps even with the memory management unit and instruction- and data-cache controllers enabled.

Atmel's AT91SAM9263 integrates 18 simple, silicon-efficient, single-cycle, peripheral DMA controllers (PDC), five DMA controllers with burst mode support to the USB host, Ethernet MAC, camera interface, LCD controller and 2D graphics controller, plus a memory-to-memory DMA controller with burst mode, scatter-gather and linked lists support. The DMA controllers completely off- load the execution of data transfers between external serial interfaces and memories. At a 20 Mbps data rate, Atmel's SAM9263 still has 88% of its MIPS available for application execution.

Atmel has implemented 11 busses and 96 Kbytes of on-chip scratchpad SRAM on the AT92SAM9263. The SRAM can be partly configured as tightly-coupled data and instruction memory (TCM). The busses provide multiple parallel on-chip data transfer channels and a total on-chip bandwidth of 41.6 Gbps.

The AT91SAM9263 has two external bus interfaces (EBI): one for the system memory and one for the human interface. The second EBI eliminates the need for the LCD controller and CPU to share memory and can increase available CPU MIPS by 20% to 40%, according to the company
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The AT91SAM9263 is available now in a 324-ball BGA package.