Targeting data logging applications such as ambulatory medical monitoring, Atmel has added three new microcontrollers to its SAM7 family of ARM-based USB MCUs.
Available in Flash memory densities of 32-, 256-, and 512-Kbytes, the SAM7SE microcontrollers include an external bus interface (EBI) that provides access to massive amounts of external NAND Flash, SDRAM, CompactFlash, SRAM and ROM storage, which many data logging applications require.
The EBI on Atmel's AT91SAM7SE MCUs supports 32-bit NAND Flash, SDRAM and CompactFlash memories in TrueIDE mode. It includes a NAND Flash controller with a complementary error-correcting code controller (ECC) that compensates for bits that are lost by NAND flash memory over time.
A built-in memory controller offers up to eight configurable chip selects and supports a wide range of 16- and 32-bit static devices including SRAM, ROM, Flash, memory mapped LCD and FPGA.
The new devices feature a security bit and MPU to protect on-chip Flash from external accesses, a major problem when external memory or logic is used, making them less vulnerable to external, potentially unauthorized, access.
To ensure security of the code, the has incorporated a trio of protection features, including: 1) mechanisms that prevent the MCU from booting from external memory; 2) a Flash security bit disables the Fast Flash Programming Interface (FFPI) and JTAG access to the on-chip Flash memory; and 3) a memory protection unit (MPU) can be configured to enforce code execution from on-chip Flash, thereby preventing execution from an outside source.
Dual-bank Flash memory on the 512 KByte SAM7SE allows true read-while-write capability so systems can be reprogrammed while continuing to operate. The dual-bank memory also protects the system from power failures or other errors that can cause an unrecoverable system failure.
The devices incorporate peripheral DMA controllers which support high speed 25 Mbps SPI with direct store in external memory. Like Atmel's other SAM7 MCUs, the SAM7SE-series has an 11-channel peripheral DMA controller (PDC) that increases on-chip bandwidth to 10 Mbps while maintaining 96% of the CPU's cycles for application processing. The PDC can store the streaming content directly in the external NAND Flash or SDRAM without CPU intervention.
The 55 MHz SAM7SE512 MCU includes the same supervisory features found on 8-bit MCUs including a brown-out detector, power-on- reset, real-time clock, crystal oscillator, watchdog timer and three 16-bit timers.
Communication interfaces include three USARTs, USB, TWI, I2S (SSC) and SPI. The device also has four pulse width modulators (PWM), an 8-channel, 10-bit analog-to-digital controller (ADC) and 88 I/O pins.
Three PIO controllers allow simultaneous peripheral access avoiding the problems that occur when an MCU multiplexes multiple peripheral accesses. When the EBI is not in use, all peripherals can be accessed simultaneously.
The AT91SAM7SE512 is available now in 128 pin Green QFP or BGA packages and priced at $8.43 and $9.38, respectively, in quantities of 10,000. The AT91SAM7SE256 and AT91SAM7SE32 will be available in early 2007.
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