San Jose, Calif. Atmel Corp.'s newest ARM926EJ-S - based microcontroller packs the peripherals enabling on-chip data transfer rates of up to 41.6 Gbps.
The newest member of Atmel's SAM9 family, the AT91SAM9263 employs 27 DMA channels including Atmel's 18-channel peripheral DMA controller, a nine layer bus matrix, and two additional busses for data- and instruction-tightly-coupled-memories, that boost CPU performance and on-chip data transfer rates of up to 41.6 Gbps. Two external bus interfaces (EBIs) allow support for GByte-plus external memories.
In addition, the new MCU boasts on-chip human interface peripherals that include a camera interface, TFT/STN LCD controller, a 6-channel audio front end interface (AC97), I2S and a 2-D graphics co-processor that off-loads line draw, block transfer, polygon fill, and clipping functions from the CPU.
Networking and Communications.
Networking peripherals include a 12 Mbps USB host and device, 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.
Support for external mass storage devices is provided by a USB host, SD/MMC memory card interface (MCI) and dual external bus interface supporting SDRAM, NAND Flash with error code correction (ECC) and CompactFlash that supports True IDE mode interface to GByte-plus on-board or removable memory including USB sticks, CompactFlash hard disks and memory cards.
Conventional ARM9-based processors use load/store instructions that require at least eighty CPU cycles to transfer a single byte of data between a memory and a peripheral. Running at 200 MHz with a bus frequency of 100 MHz, these processors typically saturate about 20 Mbps, even with the memory management unit, instruction and data cache controllers enabled. Twenty Mbps is not enough bandwidth to service an SPI or SSC, much less to handle 100 Mbps Ethernet transfers. At the 20 Mbps maximum data rate, a conventional ARM926EJ-S CPU cannot do any application processing at all because all its cycles are being used to transfer data.
Atmel's AT91SAM9263 solves this problem by integrating 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 for example the SPI and memories. At a 20 Mbps data rate, Atmel's SAM9263 still has 88% of its MIPS available for application execution.
Traditional 32-bit processors with a single 100 MHz bus, have a maximum on chip transfer rate of just 3.2 Gbps to handle all instructions and all data shifted back and forth between the on- and off-chip memories, CPU and the peripherals. In data-intensive applications such as Internet radio where audio quality is a direct function of the ability to receive and process streaming content in defined timeslots, or GPS navigation involving interactive vector graphics, the bus itself becomes a bottleneck. Atmel has solved this problem by implementing eleven busses and 96 Kbytes of on-chip scratchpad SRAM on the AT91SAM9263. 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.
Seven dedicated busses run between the DMA controllers of the Ethernet MAC, USB host, Camera interface, LCD controller, 2D-graphics co-processor, the 2-channel memory to memory DMA controller and the 18-channel peripheral DMA controller (PDC) and on- and off-chip memory. Two additional busses, one for data and one for instructions, connect the processor with the tightly coupled memories. Finally, two more busses connect the instruction and data cache controllers to the memories. Once the memory address and block size are configured, the DMAs transfer data automatically. No additional programming is required. When two DMA's and/or the processor access the same memory, an arbiter controls the access using round robin, fixed or default master arbitration schemes, as selected by the programmer.
Dual EBI allows simultaneous, parallel operation of the ARM9 CPU and graphics processors. The graphics in 2-D man-machine interfaces require nearly a GByte of external memory for the frame buffer alone, plus a 432 Mbps data rate just to refresh a 640 x 480 24-bit LCD (24-bit true-color mode). The required bandwidth is out of reach for conventional ARM9s. Atmel has addressed this issue by adding to its AT91SAM9263 two external bus interfaces (EBI): one for the system memory and one for the human interface. The second EBI has dedicated busses to both the on-chip 2-D graphics co-processor and the LCD controller. The second EBI eliminates the need for the LCD controller and CPU to share memory, and can increase available CPU MIPS by 20- to 40percent.
System and Power Control
The AT91SAM9263 includes a comprehensive suite of system and power control functions that includes main oscillator, two phase lock loops (PLLs), watchdog timer, two real-time timers, reset controller (RSTC), two power on reset units, 8-level priority Interrupt controller (AIC), shutdown controller (SHWDC), four pulse width modulators (PWM) and a periodic interval timer (PIT). System clock frequency is scalable and peripheral clocks can be enabled and disabled all under software control, optimizing dynamic power consumption to system requirements at any time.
Battery is backed up RTC with integrated power switch. An isolated battery backed-up section of the AT91SAM9263 integrates a 32 KHz crystal oscillator, real time clock (RTC) and twenty 32-bit registers. Whenever the main-supply shuts down, an on-chip power switch automatically switches power from main supply to the backup battery. In battery-backup mode the current drain is only 5microA.
For details of the processor, see block diagram below.
See related image
The AT91SAM9263 is available now in a 324-ball BGA package and is priced at sub $10 for 100K parts.
Atmel Corp. (408) 451-2855