SAM7 data
AT91SAM7S256
The AT91SAM7S256 is a low pincount Flash microcontroller based on the 32-bit ARM7TDMI RISC processor. It features 256K bytes of embedded high-speed Flash with sector lock capabilities and a security bit, and 64K bytes of SRAM. The integrated proprietary SAM-BA Boot Assistant enables in-system programming of the embedded Flash.
Its extensive peripheral set includes a USB 2.0 Full Speed Device Port, USARTs, SPI, SSC, TWI and an 8-channel 10-bit ADC. Its Peripheral DMA Controller channels eliminate processor bottlenecks during peripheral-to-memory transfers. Its System Controller manages interrupts, clocks, power, time, debug and reset, significantly reducing the external chip count and minimizing power consumption.
In industrial temperature, worse case conditions the maximum clock
frequency is 55MHz. Typical core supply is 1.8V, I/Os are supplied at
1.8V or 3.3V and are 5V tolerant. An integrated Voltage Regulator
permits single supply at 3.3V. The AT91SAM7S256 is supplied in a
64-lead LQFP or QFN Green package.
Further data can be found on the Atmel site
Next step is to sort out a set of open source tools that can be used to program it.