參考資料：
https://github.com/steward-fu/website/releases/download/miyoo-mini-plus/spi.img
必要條件：
1. UART可以使用
2. SPI IPL存在(前400KB)
更新步驟：
1. 格式化MicroSD的第一分區成FAT32
2. 將spi.img放到MicroSD根目錄
3. 按住鍵盤的Enter鍵(讓UART傳送Enter按鍵，藉此中斷U-Boot繼續執行)
4. Miyoo Mini Plus開機
SigmaStar # version
U-Boot 2015.01 (Mar 26 2023 - 23:38:58)
arm-linux-gnueabihf-gcc (GNU Toolchain for the A-profile Architecture 8.2-2018-08 (arm-rel-8.23)) 8.2.1 20180802
GNU ld (GNU Toolchain for the A-profile Architecture 8.2-2018-08 (arm-rel-8.23)) 2.30.0.20180625
SigmaStar # mmc dev 0
switch to partitions #0, OK
mmc0 is current device
SigmaStar # fatls mmc 0
get_dev_hwpart (mmc, 0, 0)
get_dev_hwpart ifname mmc, name usb,reloc_get_dev 23f39c2c, select_hwpart 00000000,mmc_get_dev 23f73a84, mmc_select_hwpart 23f72a34
get_dev_hwpart ifname mmc, name mmc,reloc_get_dev 23f73a84, select_hwpart 23f72a34,mmc_get_dev 23f73a84, mmc_select_hwpart 23f72a34
part unspecified1
part_type is 2, part -2
part unspecified2
get_partition_info part 1, ret 0
return part 1
get_device_and_partition(mmc, 0) return 1, fstype=1
probe fstype = 1, info->fstype=1
probe fs_dev_desc = 00000001, info->null_dev_desc_ok=0
16777216 spi.img
1 file(s), 0 dir(s)
SigmaStar # fatload mmc 0 0x21000000 spi.img 0 0
get_dev_hwpart (mmc, 0, 0)
get_dev_hwpart ifname mmc, name usb,reloc_get_dev 23f39c2c, select_hwpart 00000000,mmc_get_dev 23f73a84, mmc_select_hwpart 23f72a34
get_dev_hwpart ifname mmc, name mmc,reloc_get_dev 23f73a84, select_hwpart 23f72a34,mmc_get_dev 23f73a84, mmc_select_hwpart 23f72a34
part unspecified1
part_type is 2, part -2
part unspecified2
get_partition_info part 1, ret 0
return part 1
get_device_and_partition(mmc, 0) return 1, fstype=1
probe fstype = 1, info->fstype=1
probe fs_dev_desc = 00000001, info->null_dev_desc_ok=0
reading spi.img
16777216 bytes read in 1190 ms (13.4 MiB/s)
SigmaStar # sf probe
Flash is detected (0x0B05, 0xC8, 0x40, 0x18)
SF: Detected nor0 with total size 16 MiB
SigmaStar # sf erase 0 1000000
_spi_flash_erase: addr 0x0, len 0x1000000 100%(cost 61079 ms)
SF: 16777216 bytes @ 0x0 Erased: OK
SigmaStar # sf write 0x21000000 0 0x1000000
_spi_flash_write to 0x0, len 0x1000000 from 0x21000000 100%(cost 29740 ms)
SF: 16777216 bytes @ 0x0 Written: OK
SigmaStar # reset
P.S. 如果有SPI燒錄器可以使用，只要將spi.img直接燒錄到SPI Flash即可