User manual

4.3. Memory
a) Flash memory
• Flash memory layout
The Stamp9261 can be equipped with 16MB, 32MB, 64MB, 128MB Flash memory. This is organized
in blocks of 128KB. Each block can be erased individually.
The flash memory is made up of 1 IC. In case that 128MB chips should be installed, the PIO line PC0
is used as A26, as the CPU has only 26 external address lines.
• Limited number of erase cycles
The Flash memory consists of "Large Sector Flash-ICs" (e.g. Spansion’s S29GL256 or similar). Only
a limited number of erase cycles per block are tolerable for these devices (usually one hundred
thousand erase cycles are guaranteed by the manufacturer). This means that the flash memory, in
particular the flash disk, is not suitable for permanent write operations of a program, since the
permissible number of erase cycles per block might be exceeded in a relatively short time. A RAM disk
must be used for such purposes.
b) Boot Mode Select Signal (BMS)
This pin is normally low and enables the standard boot code from the Stamp9261's flash memory. If
pulled high, the Stamp9261 boots from the internal ROM of the SAM9261 processor. The ROM code
initializes the CPU and tries to boot from an external DataFlash
®
memory. Currently, the Stamp9261
provides no support for using the ROM code. This ROM-boot program also supports the SAM-BA
programming tool from Atmel©
c) EEPROM
256 Bytes within a serial EEPROM are available to store configuration data. The EEPROM is
accessed via the TWI.
d) SDRAM
The Stamp9261 can be equipped with up to 64MB SDRAM. The starter-kit Stamp9261 is equipped
with 64MB Mobile SDRAM.
e) SRAM
The SAM9261 processor integrates 160 KB of fast static RAM which can be used as "Tightly Coupled
Memory" (TCM) with dedicated instruction and data blocks. Time-critical sections of the code, e.g.
interrupt handlers, are recommended to be placed within the SRAM, as well as critical data sections
like the stack.
f) DataFlash
A 128 KB Dataflash connected to the processor's SPI-Bus is provided. It can be used for booting
purposes or storing configuration data in designs without further flash memory
- 9 -