Photo Frame "hacks"

An easy way to hook up digital photo frames (DPF) to your own microcontroller.

Unfortunately, ready or easy to use displays are not that cheap.
Even if you manage to get your hands on a "cheap" bare display, a lot of perihperals and surrounding parts are necessary and need to be developed by you.

In addition to the glass panel (the LCD/TFT) itself, one needs at least:

  • several voltages
  • a power supply sequence
  • several sync signals
  • VCOM generation and "calibration" (contrast/flicker/gamma)
  • grayscale generator (gamma)
  • constant offset, AC RGB signals
  • special LCD cable connectors
  • PCB (although I know some guys who wirewrapped this ;-)
  • a lot of knowledge...

But these days, millions of ready to use DPFs can be bought at <1/10 of the cost of a bare glass panel and additionally, they come with all the electronics, required to control the display, a case, cheap remote control, a power supply, ...

99% of these cheap displays have analog inputs (and even if it looks digital, the glass panel itself always operates analog). They are not fed by digital pixel data, but analog RGB signals, like your big "old" VGA displays, with one big difference:

The "pixels" of these cheap displays can not be driven by a pure DC-level. Over all (time), an AC signal is required, hence the polarity of each color signal needs to be inverted after each display line.
Disobeying this will damage the panel (burn-in images or colors). "A pixel needs 0(V)".

Fortunately, any DPF include all of the above. They create all the necessary voltages, sync-signals and do even care about the backlight.

Well, what's easier than letting the DPF do the hard work, while we lean back and let another processor inject some RGB signals?

child's play...
(but don't blame it on me if you trash all your nice panels...)

Basic Examples: "PropanLCD"

PropanLCD, the Propeller Analog LCD Demonstrator.
If you still haven't a Prop, get one. It really provides unlimited amount of fun ;-)

a DPF stand

ye+bl: frame start ("vsync"; scan start)
pur: "hsync"
gr: video signal

Well, someday, a little more text will appear <right here>.

VCOM, polarity change...
...and inverted
REV and VCOM generation...
...and inverted

sine wave injection

Here Be Signals
(Lharon Cay Denman)

minimal Prop connection
NOTE: add 75E (47-200E) resistors
from R,G,B to GND in DPF

white (inverted)

frame start, REV and ~3 lines
of a black to white ramp

a closer view


invisible lines
(DC compensation)

"waitpeq" (opcode) jitter
(Prop not synced to DPF)

...and its effects

in the lab...
a finer y resolution
effects of asynchronous operation
Prop powered by its own crystal
Just take XIN and wire it... the DPF's pixel clock

As you might have noticed, all the text is missing...
Just a quick and fresh upload, so far.

The download is already available. There indeed is a lot of information in the SPIN file.
Download the "PropanLCD Demonstrator", guess what, in the download section...

to be uploaded...

Making it fast: "54STM32LCD10BOOM"

to be uploaded...

Mini: "PIC, tu tombes à pic!" (PTTAP)

to be uploaded...

Weird Stuff: "SOWX-LCD-XMOS"

only the amount of RAM
limits the resolution

only a few pins are required
(e.g.: XK-1 board connections)

An XMOS based LCD display controller, using a cheap digital photo frame.

upcoming attraction...


Key Ring Photo Frame

All around the world, this little display is sold as a key ring.
Although the appearance, as well as the brand, varies ("Tom-Tec", "Bresser",...), the internals are equal. I bought a few of them for less than 3EUR. Batteries included ;-)

Despite its cheap character, this one has a controller built in, a Sitronix ST7637.

This is almost the same display as seen in Raisonance's Primer 1 STM32 development kit. The display itself, a PZG15BW-SCLW is manufactured by Palm Technology, includes the same controller but has 32 pins instead of only 27 (but same functions). Source code and schematics are available on their site.

Others, who played around with this display:

1 2 6 5 7 8 9 10 12 14 16 18 20 22 24 26 27



- Propeller SPIN/PASM source code (SPIN)
- nothing more, nothing less
DOWNLOAD: Propeller demo source code SW; V0.7

ASkr 03/2008 initial release
ASkr 09/2009 added some new displays
ASkr 07/2010 complete redesign