AT91SAM9G35-CU Datasheet, PDF (61/1224 Pages) ATMEL Corporation – AT91SAM ARM-based Embbedded MPU

11.4.4.4 SPI Flash Boot
Two kinds of SPI Flash are supported: SPI Serial Flash and SPI DataFlash.
The SPI Flash bootloader tries to boot on SPI0 Chip Select 0, first looking for SPI Serial Flash, and then for SPI
DataFlash.
It uses only one valid code detection: analysis of ARM exception vectors.
The SPI Flash read is done by means of a Continuous Read command from address 0x0. This command is 0xE8 for
DataFlash and 0x0B for Serial Flash devices.
Supported DataFlash Devices
The SPI Flash Boot program supports all Atmel DataFlash devices.
Table 11-3. DataFlash Device
Device
AT45DB011
AT45DB021
AT45DB041
AT45DB081
AT45DB161
AT45DB321
AT45DB642
Density
1 Mbit
2 Mbits
4 Mbits
8 Mbits
16 Mbits
32 Mbits
64 Mbits
Page Size (bytes)
264
264
264
264
528
528
1056
Number of Pages
512
1024
2048
4096
4096
8192
8192
Supported Serial Flash Devices
The SPI Flash Boot program supports all SPI Serial Flash devices responding correctly at both Get Status and
Continuous Read commands.
11.4.4.5 TWI EEPROM Boot
The TWI EEPROM Bootloader uses the TWI0. It uses only one valid code detection. It analyzes the ARM exception
vectors.
Supported TWI EEPROM Devices
TWI EEPROM Boot supports all I²C-compatible TWI EEPROM memories using 7-bit device address 0x50.
11.4.5 Hardware and Software Constraints
The NVM drivers use several PIOs in peripheral mode to communicate with external memory devices. Care must be
taken when these PIOs are used by the application. The devices connected could be unintentionally driven at boot time,
and electrical conflicts between output pins used by the NVM drivers and the connected devices may occur.
To assure correct functionality, it is recommended to plug in critical devices to other pins not used by NVM.
Table 11-4 contains a list of pins that are driven during the boot program execution. These pins are driven during the boot
sequence for a period of less than 1 second if no correct boot program is found.
SAM9G35 [DATASHEET] 61
11053D–ATARM–11-Feb-13