The AT91SAM9G20 is based on the ARM926EJ-S processor, with a clock speed of 400MHz. It features 32K byte instruction and 32K byte data cache memories, two 16K-byte blocks of SRAM and 64K bytes of ROM with single cycle access at maximum processor or bus speed, together with an external bus interface with controllers for SDRAM and static memories including NAND Flash and CompactFlash. Its extensive peripheral set includes USB Full Speed Host and Device interfaces, a 10/100 Base T Ethernet MAC, Image Sensor Interface, Multimedia Card Interface (MCI), Synchronous Serial Controllers (SSC), USARTs, Master/Slave Serial Peripheral Interfaces (SPI), two three-channel 16-bit Timer Counters (TC), a Two Wire Interface (TWI) and four-channel 10-bit ADC. Three 32-bit Parallel I/O Controllers multiplex the pins to/from these peripherals in order to reduce the device pin count, and peripheral DMA channels maximize the data throughput between these interfaces and the on- and off-chip memories.

The AT91SAM9G20 has a fully featured system controller for efficient system management, including a reset controller, shutdown controller, clock management, advanced interrupt controller (AIC), debug unit (DBGU), periodic interval timer, watchdog timer and real-time timer. It is available in a 217-ball LFBGA RoHS-compliant package.

The AT91SAM9G20 is supported by the AT91SAM9G20 Evaluation Board and extensive third-party application development tools. It supports both Linux and Windows CE.