DHT-Walnut PPCBoot

Quick notes on updating from stock ppcboot v1.1.2 to GPSFan's ppcboot v1.1.6

• Boot the board and bring it to the ppcboot console prompt.
• Check current flash configuration:

=> flinfo

Bank # 1: AMD AM29F040 (512 Kbit, uniform sector size)
  Size: 512 KB in 8 Sectors
  Sector Start Addresses:
    FFF80000  RO  FFF90000  RO  FFFA0000  RO  FFFB0000      FFFC0000
    FFFD0000      FFFE0000      FFFF0000     

Note that the bottom three sectors, containing the existing 1.1.2 bootloader, are protected. We also want to protect the last sector, which contains the initial jump instruction, so:

=> protect on ffff0000 ffffffff

Protected 1 sectors

• Now download the new bootloader into ram:

=> loadb 400000 115200

## Switch baudrate to 115200 bps and press ENTER ...
## Ready for binary (kermit) download ...
## Start Addr      = 0x00400000
## Switch baudrate to 9600 bps and press ESC ...

• Erase the three spare sectors, which we'll use to backup the 1.1.2 bootloader:

=> erase fffc0000 fffeffff

Erase Flash from 0xfffc0000 to 0xfffeffff
Erasing sector fffc0000
.Erasing sector fffd0000
.Erasing sector fffe0000
. done
Erased 3 sectors

• (Optional: erase the 0xfffb0000 sector, which will be used for non-volatile environment storage.)

=> erase fffb0000 fffbffff

Erase Flash from 0xfffb0000 to 0xfffbffff
Erasing sector fffb0000
. done
Erased 1 sectors

• Check that sectors 0xfffc0000 to 0xfffe0000 are erased, and sector 0xffff0000 is protected:

=> flinfo

Bank # 1: AMD AM29F040 (512 Kbit, uniform sector size)
  Size: 512 KB in 8 Sectors
  Sector Start Addresses:
    FFF80000  RO  FFF90000  RO  FFFA0000  RO  FFFB0000 E    FFFC0000 E
    FFFD0000 E    FFFE0000 E    FFFF0000  RO 

• Now we're ready to backup the 1.1.2 bootloader. Copy three sectors from 0xfff80000 to 0xfffc0000:

=> cp.b fff80000 fffc0000 30000

Copy to Flash... done

• Easy enough, right? Compare just to be sure it went ok:

=> cmp.b fff80000 fffc0000 30000

Total of 196608 bytes were the same

• Now we're ready to modify the bootsectors. We'll turn off protection, erase the three bottom sectors, and copy the new 1.1.6 bootloader from ram.

• Unprotect the bottom three sectors:

=> protect off fff80000 fffaffff

Un-Protected 3 sectors

From this point on, do *not* power down the board. This is the critical section.

• Erase the bottom three sectors with the original 1.1.2 bootloader:

=> erase fff80000 fffaffff

Erase Flash from 0xfff80000 to 0xfffaffff
Erasing sector fff80000
.Erasing sector fff90000
.Erasing sector fffa0000
. done
Erased 3 sectors

• Copy the new bootloader into flash:

=> cp.b 400000 fff80000 30000

Copy to Flash... done

• Verify the copy:

=> cmp.b 400000 fff80000 30000

Total of 196608 bytes were the same

End of critical section. Congratulations'

• We've finished modifying flash, so turn the write protection back on:

=> protect on fff80000 fffaffff

Protected 3 sectors

To sum up, you'll end up executing 10 commands:

=> protect on ffff0000 ffffffff

=> loadb 400000 115200

=> erase fffc0000 fffeffff

=> cp.b fff80000 fffc0000 30000

=> cmp.b fff80000 fffc0000 30000

=> protect off fff80000 fffaffff

=> erase fff80000 fffaffff

=> cp.b 400000 fff80000 30000

=> cmp.b 400000 fff80000 30000

=> protect on fff80000 fffaffff