环境：
PC设置静态IP地址：192.168.1.100
PC用网线连接ONU的LAN口
PC使用串口排线连接到ONU上串口排针上
PC开启tftp server
PC开启可以通过串口连接ONU的软件：如IPOP，SecureCRT，XSHELL
PC----以太网线----ONU
|-----------串口线--------|
1. 擦除flash所有配置信息
Hit any key to stop autoboot: 0
=>
=>
=> 1. 擦除flash内部所有信息
=> sf probe
SF: Got idcode ef 40 18 00 00
SF: Detected w25q128 with page size 64, total 16 MiB
=>
=> sf erase 0 1000000 如果执行该命令后可能导致指令无法执行的话就意味着系统挂死，需要通过UART方式进行升级
zx_spifc_erase:start erase addr 0x0
…
…
zx_spifc_erase:end erase addr 0x1000000
=>
=> downver boot 就如前面说的，执行这个命令无反应，因此需要通过UART模式升级，先是短接J3这两个口，再上下电源 进入UART模式下“”ROM#“”
SPI NOR
SPI NOR
SPI NOR
SPI NOR
UART
ROM# x 升级uart文件
REC: CCCCCCC
OK
ROM# g 升级uboot文件，传输完成后系统会重启，需要手动按回车键 进入uboot串口升级模式下 “=>” ,再次执行升级uboot和image文件即可 完成升级操作
00200000spl booting…
U-Boot SPL 2013.04 (Mar 18 2019 - 11:44:55)
spi boot failed,use uart boot, pls transfer boot through 1K-Xmodem @115200…
CCCCCC
U-Boot 2013.04 (Mar 18 2019 - 11:44:55)
CPU : ZX279125@A9,600MHZ
Board: ZXIC zx279125evb
I2C: ready
DRAM: 32 MiB
SF: Got idcode ef 40 18 00 17
SF: Detected w25q128 with page size 64, total 16 MiB
*** Warning - bad CRC, using default environment
In: serial
Out: serial
Err: serial
Net: eth0
Hit 1 to upgrade softwate version
Hit any key to stop autoboot: 0
=>
=>
=>
=>
=>
=> downver boot 升级uboot文件
mac 1 phy status changed: 1000M full-duplex
Using eth0 device
TFTP from server 192.168.1.100; our IP address is 192.168.1.1
Filename ‘uboot.bin’.
Load address: 0x40600000
Loading: #############
4.5 MiB/s
done
Bytes transferred = 184384 (2d040 hex)
please wait, Erasing 0x0 - 0x80000:
zx_spifc_erase:start erase addr 0x0
…
zx_spifc_erase:end erase addr 0x80000
[Done]
Writing to SPI flash:spi_nor_write_bytes start addr 0x0 len 0x2d040
…
[Done]
Saving Environment to SPI Flash…
Erasing SPI flash…zx_spifc_erase:start erase addr 0x40000
.
zx_spifc_erase:end erase addr 0x50000
Writing to SPI flash…spi_nor_write_bytes start addr 0x40000 len 0x10000
…
done
=> downver version 升级image文件
Using eth0 device
TFTP from server 192.168.1.100; our IP address is 192.168.1.1
Filename ‘upgrade.bin’.
Load address: 0x40600000
Loading: #################################################################
#################################################################
#################################################################
#################################################################
#################################################################
#################################################################
##############################################
5 MiB/s
done
Bytes transferred = 6389936 (6180b0 hex)
please wait, Erasing 0x0 - 0x80000:
zx_spifc_erase:start erase addr 0x0
…
zx_spifc_erase:end erase addr 0x80000
[Done]
Writing to SPI flash:spi_nor_write_bytes start addr 0x0 len 0x2d040
…
[Done]
please wait, Erasing 0x80000 - 0x180000:
zx_spifc_erase:start erase addr 0x80000
…
zx_spifc_erase:end erase addr 0x200000
[Done]
Writing to SPI flash:spi_nor_write_bytes start addr 0x80000 len 0x12b028
…
[Done]
please wait, Erasing 0x200000 - 0x580000:
zx_spifc_erase:start erase addr 0x200000
…