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For more interesting projects done by Flameman, be sure to check out his project index



This project is deprecated, RIP. Jtag software is also deprecated, vendor removed the support for amcc44x.

== New projects, 2017-2019, at DTB

See here


The Target-goal of this page is

  • install gentoo-ppc32 into harddisk
  • make the board able to boot from it
  • describe how to build a jtag cable (to debug and recover from "Brickage")
  • describe something useful with you can do with the board
  • describe other Operating System available for the board

logical steps about installing gentoo

  • add the JTAG connector at J10 (you could skip it, it is suggested)
  • build the JTAG cable (you could skip it, it is suggested))
  • replace the bootloader with ppcboot 1.1.6/U-boot 1.1.4
  • make partitions on the Hard Disk
  • populate them
  • set the bootloader environment to boot from the Hard Disk

People you could contact if you need help

Please let me know of any success or issues you encounter. carlojpisani@gmail.com

About the board

DHT-Walnut is a shortened name for the Digital Home Technologies PCB 01070201 Rev. 1.1.

The DHT-Walnut board is based on the AMCC-Walnut (still available, and still expensive :P). It is a more improved board described at www.amcc.com.

A "walnut" searching will inform about schematic and software.

Also keep attention @ DENX: they have developed a lot for the AMCC-Walnut board, and you could find a linux patch for your problem, prettier documentation, developer suit, and much more: in case, you are suggested to have a look to their web pages.

you could find it on ebay, search for "walnut", or "powerpc"

MIND UP the differences between "DHT WALNUT" and "AMCC WALNUT" (ALSO CALLED "IBM WALNUT")


The board consists of:

  • CPU PowerPC 405GP running at 266mhz
  • RAM PC133 SDRAM slot, currently, only supports single sidded DIMMs
  • LAN On-chip 405GP ethernet, board doesn't have an ethernet MAC address (the monitor/bootloader is able to fix it)
  • UART DCE serial port, speeds up to 230k, only tested to 115200bps
  • PCI two pci slots, keyed for 5V only cards
  • IDE Promise Technologies PDC20265 IDE
  • ROM 512k of boot flash, AMD 29LV040B (amd29lv040b.pdf), soldered on the PCB, if you like to use a socket you have to consider the bootloader will check for the flash manufactor ID, so or you replace the 29LV040B with an other socked-29LV040B, or you have to modify the bootloader
  • POWER the board need to be 12v dc powered 2A max, it is able to feed the hard disk
  • System PCB 6.00" x 7.5" board size
  • RTC the real time clock chip is missing
  • RAM 32M PC133 SDRAM DIMM, the board has issues with more than 128M: if you inspect the pcb, you will see that the DIMM connector has same pin missing, this is the reason why you can't use DIMM bigger than 128M
  • PCI IEEE-1394 card supported by OHCI driver
  • PCI additional ethernet board needed cause the on board ethernet is implemented by the IBM-ppc-405GP, for example netbsd is not able to drive it, so in case you need an additional board, the one provided with DHT is good enough
  • FIRMWARE PPCBoot v.1.1.2 in flash (it has issues with environment, it need to be replaced with a gooder one)

Images of the board


see more detailed photo dht-walnut-ppc405-top


The BEST solution is to equip your lab with the bdi2000. This hardware is expensive a lot, 'cause it is not a simple download cable, it's a professional debugger

For this dht-walnut project it has been used "OCD Commander is macraigor's free debugger software", that i'm going to illustrate


Firnware and Bootloaders

  • ppcboot (not suggested)
  • U-Boot (it can't load kernel >=2.5.25)
  • U-Boot-kanojio (under development, it will be able to boot kernel >2.6.25, see below)


about issues, and ideas, they are also reported here Flameman/dht-walnut/rootfs#firmware_issues_with

about uboot



storage device: HardDisk, microdrive or Compact Flash, put a rootfs on it



  • Netbsd has a port for "IBM PowerPC 405GP based Walnut evaluation board", this is not the DHT-Walnut, this is another way to call the AMCC-Walnut (yes just to be confusing). Ok, it is not for DHT-Walnut, but this port could be (easily / hardly) adapted to the DHT-Walnut with some work


Project: do something useful with the board


thinking new things ... but it should be compatible with "free time constraints" =P

See also Flameman/dht-walnut/develop

if you need pci-riser

PCI Riser Card 5V 32-bit 2 Slot passive Edge connector X1 of the riser card is inserted in a free 5 V 32-bit slot on the PC motherboard. Slot X2 is then connected and ready for use. The second PCI slot X3 receives its special signals for bus arbitration and interrupt control via the cable from card X4, which is inserted in any other slot on the PCI motherboards. The assembly does not contain any active components. This means that the board is suitable for operation with V(I/O) = 5 V as well as V(I/O) = 3.3 V. The coding of connectors X2 and X3 with this variant is for V(I/O) = 5 V.