AT91SAM7S256D-AU Atmel, AT91SAM7S256D-AU Datasheet - Page 98

• Manufacturer Part Number: AT91SAM7S256D-AU
• Description: ARM Microcontrollers - MCU 256K Flash SRAM 64K ARM based MCU
• Manufacturer: Atmel
• Series: SAM7S256r

Specifications of AT91SAM7S256D-AU

• Rohs: yes
• Core: ARM
• Processor Series: AT91SAM
• Data Bus Width: 16 bit/32 bit
• Maximum Clock Frequency: 55 MHz
• Program Memory Size: 256 KB
• Data Ram Size: 64 KB
• On-chip Adc: Yes
• Operating Supply Voltage: 3 V to 3.6 V
• Operating Temperature Range: - 40 C to + 85 C
• Package / Case: LQFP-64
• Mounting Style: SMD/SMT
• Interface Type: 2-Wire, I2S, SPI, USART
• Length: 7 mm

18.3.1
18.3.2
18.3.2.1
It is made up of:
The MC handles only little-endian mode accesses. The masters work in little-endian mode only.
The Memory Controller has a simple, hard-wired priority bus arbiter that gives the control of the bus to one of the
two masters. The Peripheral DMA Controller has the highest priority; the ARM processor has the lowest one.
The Memory Controller features an Address Decoder that first decodes the four highest bits of the 32-bit address
bus and defines three separate areas:
Figure 18-2
Figure 18-2. Memory Areas
Within the Internal Memory address space, the Address Decoder of the Memory Controller decodes eight more
address bits to allocate 1-Mbyte address spaces for the embedded memories.
The allocated memories are accessed all along the 1-Mbyte address space and so are repeated n times within this
address space, n equaling 1M bytes divided by the size of the memory.
When the address of the access is undefined within the internal memory area, the Address Decoder returns an
Abort to the master.
• A bus arbiter
• An address decoder
• An abort status
• A misalignment detector
• An Embedded Flash Controller
• One 256-Mbyte address space for the internal memories
• One 256-Mbyte address space reserved for the embedded peripherals
• An undefined address space of 3584M bytes representing fourteen 256-Mbyte areas that return an Abort if
Bus Arbiter
Address Decoder
accessed
Internal Memory Mapping
shows the assignment of the 256-Mbyte memory areas.
14 x 256MBytes
256M Bytes
256M Bytes
3,584 Mbytes
0xF000 0000
0x0000 0000
0xEFFF FFFF
0x0FFF FFFF
0xFFFF FFFF
0x1000 0000
Internal Memories
Peripherals
Undefined
(Abort)
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
98