This port was made by a combination of mostly 3 hackers to start with:

• Michel Pollet aka @BusError
• Jeroen aka @SpriteMods aka Sprite_tm
• Claude Schwarz aka Claude :-)

With excellent contributions from Simon Taylor in particular, and a few others, including Bifferos of the bifferboard project.

This 3.5" display frame seems to have the highest potential for hackability so far.  When compared to the hacked keychain models, this has a much faster CPU, larger screen, more RAM and is hardly any more expensive. As of Nov 2010, they are on Amazon for a ridiculous £10!  (@Biff) I have some theories as to why.

This frame is now "owned" almost entirely and can run linux without needing JTAG or even a uart cable.  Here is a screenshot of the 320x240 display running the Linux framebuffer:

The Frame running the 'sdl newvox' demo with wiimote input:

Toolchain/rootfs

Suggested to use minifs as this builds toolchain, kernel and rootfs all in one go.  You will need to install lzop, uboot-mkimage, libelf-dev, libncurses-dev, checkinstall and any other tools requested.  You don't need to be root to run any of this.

% git clone http://oomz.net/git/minifs.git minifs

% cd minifs
% export MINIFS_BOARD=df3120
% ./minifs_build.sh
% ls -l build-df3120/minifs-full-ext.img
-rw-r--r-- 1 8388608 build-df3120/minifs-full-ext.img

NB:  For the impatient I've added my version to the bottom of this page, don't forget to decompress it with
bzip2 -d minifs-full-ext.img.bz2 before using!

Once you've build the rootfs, you'll need to copy it to the one and only partition on an SD card, e.g.:

% dd if=build-df3120/minifs-full-ext.img of=/dev/sdb1

Add the toolchain bin directory to your path before compiling anything, e.g.:

% export PATH=$PATH:~/minifs/toolchain/arm-v4t-linux-uclibcgnueabi/bin

u-boot

Solderless Firmware 'Upgrade' to Linux

The easiest way to get linux onto the frame is to use a utlity called plftool to create a fake firmware upgrade, which the frame then picks up and runs as part of it's normal firmware upgrade process.  This has been tested with versions 1.1 and 1.2 of the Parrot firmware.



Having created the firmware update, install it as follows:

• Switch on the frame without any SD card inserted, with a USB cable connecting it to your PC.
  
• When it shows up, mount the device somewhere (not the partition), e.g. mount /dev/sdc /mnt/hd
• Create a directory on the USB storage device called 'update'.
• Copy parrotDF3120.plf to the 'update' directory you created.
• Leaving the power connected and the frame on, unplug the USB cable.
• You should see four squares appear on the screen, the top left one will be blue and the others green.  This means the firmware has been updated correctly.
  

NB:  See below for a pre-built version of parrotDF3120.plf, which seems to work.

Troubleshooting:  If you find that Linux comes up with loads of syslog errors when connecting the frame, try to mount it anyhow.  If that fails, do the same thing on a Windows or MAC machine.  This worked for some frames that failed under Linux, and you can then create the update folder and copy the file in as under Linux.

Running U-boot

If you've installed the u-boot bootloader you keep compatibility with the old firmware for displaying pictures and so on.   u-boot gets activated only when you press and hold the centre and left buttons on power-on.  When you do this you'll see the screen going blank, and if you have an SD card inserted it will attempt to boot Linux.  U-boot is able to boot a kernel direct from SD card and will look for a file called linux in the root of the ext2 fs found on the first partition.

Kernel 2.6.36.1

Note: The hardware is not fantastically designed, in fact some of the frames reports lots of problems with the original firmware. It seems mostly due to sub-par power supply.

All the frames I tried (@buserror) works when reflashed to linux, but some of them might /need/ JTAG due to the fact that the frame will not allow you to copy the .plf "soft" upgrade path...

This contains the earlier notes we had on the board, including PCB scans and early JTAG chatter.

It has:

• Samsung s3c2412 -- arm9, 266 mhz, with clean support in the linux kernel.
• Powertip PH320240 display supporting 320x240 resolution in 64k colours.
  
• 8MB SDRAM -- upgradable, see below
  
• 32MB NAND flash.
• Bluetooth. Hooked on UART 0
  
• Tilt sensor, looks like Omron D6BN1100 -- the frame knows it's "orientation"
• Light sensor (http://www.taosinc.com/ProductDetails.aspx?id=47), for PWM control on the screen backlight
• 3 buttons

The CPU is BGA, but they have very conveniently used micro-via under each pad, so all the pins are prodable from the bottom side of the board.

This device does run linux, despite the low memory. There are lots of options to use it as a slave:

• run it with usb-gadget ethernet, it will appear as a new ethernet device on the bifferboard, and can be bridged to a real network.
• use usb-storage gadget to share it's SD card slot, for fast (usb-1) access to storage from the bifferboard
• Devise a "remote frame buffer" protocol, over the usb-gadget-ethernet
  

Front Scan

All is pretty obvious here:

• 2 cheap buck regulators, U8, U11. 34063's are pretty basic.
  
• USB device port
• Bluetooth IC in the bottom right U2, with it's trace antenna along the right side
  "Blutonium BCM2045" -- See brochure attached. Reported on UART0..
  
• Light sensor bottom left U13 -- TAOS inc. TSL12T or TSL13T analog output
  Interestingly the light sensor is looking from the back of the device, there is a small clear patch in the casing. The sensor is hooked on the ADC0 of the s3c2412.
• SW14 is the on/off switch
• Not sure what U10 is
  

Back Scan

• P1 is a bias correction for the LCD voltage. If you see "waves" on your screen in normal use, this is the one to adjust.
  
• J3 is the obvious JTAG connector. See below
  OpenOCD works with the samsung s3c, we can upload a bootloader in SDRAM and run it from there.
  
• U4 is SDRAM . 4Mx16. K4S641632. A bit light for linux, but it works!
  
• U3 is NAND. K9F5608D0C is 32x8 bits. (see datasheet attached).
  
• J5 is UART0 - Bluetooth.
• J4 Is UART2 -- Console for u-boot and linux. 
• J6 is UART 1 -- it has a different pinouts than J5/J4l
  

Hardware gotcha's
The connector to the display is glued in place for a reason: it can come loose quite easily if the glue-bonds are broken. If your display acts up, you may try reseating it. If you did this and the display still fails with symptoms of a working backlight but no image whatsoever (black screen with just some backlight leaking through) check what happens when you short R132 with e.g. a pair of tweezers. The resistor is located above the display connector and can blow when the display isn't seated correctly. Replace with a resistor of preferably 1.5K, but probably any value from 470 ohm to 2K will work. Shorting the R altogether may work too, but could smoke something else when the problem blowing the resistor in the first place happens again.

Pinouts

J4/J5 Pinouts:

Pin	Function	Notes
1	GND
2	Input
3	Output

J5 is almost certainly a console of some sort, but it's mostly gibberish.  I've tested 300, 1200, 2400, 4800, 9600, 19200, 38400, 57600, 115200 but it always comes out garbage.  All these settings were 8N1, so perhaps we need to try different parity settings.

J5 seems to be the UART connected to the Bluetooth chip. J4, next to it, has the same pinout but _does_ actually output something readible at 115200,n,8,1. J5 = UART0, J4 = UART2. That'd imply J6=UART1, but I haven't checked. - Jeroen

Now u-boot and the kernel use J4 (/dev/ttySAC2) as console.