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It's essential to note that i-boot does not initialize DDR DRAM, rendering it temporarily unavailable. Hence, x-boot must be loaded into SRAM for execution.
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Device drivers
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Drivers
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i-boot supports for 5 boot devices. The following table lists the specifications of each boot device:
Boot devices | Specifications |
8-bit NAND flash | First block of 8-bit NAND flash should contain Sunplus Boot Profile Header.Support reading 1K60 ECC sectors. x-boot image should be stored in 1K60 ECC sectors.Set MS control of pins of 8-bit NAND flash. Read cycle-time is set to 240 nS. GPIO82 should be set to HIGH if 3.0V NAND flash is used or LOW if 1.8V NAND flash is used.
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eMMC device | x-boot image should be stored at Boot Area Partition 1.Set MS control of pins of eMMC device. Bus clock is set to 25 MHz. GPIO82 should be set to HIGH if 3.0V IO power is used or LOW if 1.8V IO power is used.
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SPI-NAND flash | First block of SPI-NAND flash should contain Sunplus Boot Profile Header.Support reading 1K60 ECC sectors. x-boot image should be stored in 1K60 ECC sectors. Support X1 and X2 position of SPI-NAND. First try X1 position and then X2 position. Bus clock is set to 11.Set MS control-bit of pins of SPI-NAND flash2 MHz. GPIO82 should be set to HIGH if 3.0V SPI-NAND flash is used or LOW if 1.8V SPI-NAND flash is used.
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SPI-NOR flash | x-boot image should be stored at offset 0x18000 (96Ki). Bus clock is set to 11.2 MHz. GPIO82 should be set to HIGH if 3.0V SPI-NOR flash is used or LOW if 1.8V SPI-NOR flash is used.
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SD card | x-boot image should be stored at offset 0 of the file ISPBOOOT.BIN. File The file ISPBOOOT.BIN should be stored root directory of first partition of the SD card. First or sole partition of the SD card should be FAT32 or FAT16 format. Bus clock is set to 5 MHz.
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USB2.0 HostUSB flash drive | x-boot image should be stored at offset 0 of the file ISPBOOOT.BIN. File The file ISPBOOOT.BIN should be stored root directory of first partition of the USB flash drive. First or sole partition of the USB flash drive should be FAT32 or FAT16 format. Support high-speed read operation only Support USB flash drive on both USB2.0 or USB3.0
Hostx-boot image should be stored at offset 0 of the file ISPBOOOT.BIN. File ISPBOOOT.BIN should be stored root directory of first partition of the USB flash drive. First partition of the USB flash drive should be FAT32 or FAT16 format. Support high-speed read operation onlyports. Try USB3.0 port first and then USB2.0 port.
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Boot core and other cores
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