7.4 Boot From External Memory
Several types of external memories such as NAND Flash, SDCard, SPI Flash, QSPI Flash, etc. can be connected to the SAMA5D27 SOM1 and placed on the motherboard.
For details of the Boot sequence, refer to the "NVM Bootloader Program Description for MRL C Parts" diagram of the SAMA5D2 data sheet, document no. DS60001476.
The table below provides the list of external memory types and interfaces that may be used to boot the SAMA5D27 SOM1:
| Memory Type | Interface | PIO | Comments |
|---|---|---|---|
| SDCard | SDMMC0 | PA0 to PA13 | If external SDMMC0 interface is not used, bit SDMMC_0 in Boot Configuration Word must be set to 1. |
| SDMMC1 | PA18 to PA22, PA27 to PA30 | If external SDMMC1 Interface is not used, bit SDMMC_1 in Boot Configuration Word must be set to 1. | |
| eMMC | SDMMC0 | PA0 to PA10, PA13 | If external SDMMC0 Interface is not used, bit SDMMC_0 in Boot Configuration Word must be set to 1. |
| SDMMC1 | PA18 to PA22, PA27, PA30 | If external SDMMC0 interface is not used, bit SDMMC_1 in Boot Configuration Word must be set to 1. | |
| NAND Flash | NFC | PA0 to PA12 | Field NFC in Boot Configuration Word must be set to "01". IOSET2 is selected. (See Notes below) |
| PA22 to PA31, PB0 to PB2, PC8 | Field NFC in Boot Configuration Word must be set to "00". IOSET1 is selected. (See Notes below) | ||
| QSPI Flash | QSPI0 | PA0 to PA5 | Field QSPI_0 in Boot Configuration Word must be set to "00". IOSET1 is selected. (See Notes below) |
| PA14 to PA19 | Field QSPI_0 in Boot Configuration Word must be set to "01". IOSET2 is selected. (See Notes below) | ||
| PA22 to PA27 | Field QSPI_0 in Boot Configuration Word must be set to "10". IOSET3 is selected. (See Notes below) | ||
| QSPI1 | PB5 to PB10 | Need to tie DIS-BOOT pin to GND. Bits QSPI_1 in Boot Configuration Word must be set to "01". IOSET2 is selected. (See Notes below) | |
| SPI Flash | SPI0 | PA14 to PA17 | Bits SPI_0 in Boot Configuration Word must be set to "00". IOSET1 is selected. (See Notes below) |
| PA30, PA31, PB0, PB1 | Bits SPI_0 in Boot Configuration Word must be set to "01". IOSET2 is selected. (See Notes below) | ||
| SPI1 | PA22 to PA25 | Bits SPI_1 in Boot Configuration Word must be set to "01". IOSET2 is selected. (See Notes below) | |
| PC1 to PC4 | Bits SPI_1 in Boot Configuration Word must be set to "00". IOSET1 is selected. (See Notes below) |
Note: For these external memory
configurations, set the EXT_MEM_BOOT_ENABLE bit to "1" in Boot Configuration
Word.
Note: The Boot Configuration Word allows
several customizations of the boot sequence. For details, refer to the section "Boot
Configuration" in the SAMA5D2 Data Sheet, document no. DS60001476.