several times people asked how to modify a cheap digital picture frame
(DPF) as a display device for embedded systems. Drawback is: most DPFs
use a analog TFT panel which is quite hard to drive, since there are a
zillion of supply and support voltages and AC signals needed and timing
constraints are rather strict. So, AFAIK, most DIYs gave up.
I got a very cheap 7" DPF with a 480x234 analog TFT panel which uses a
Haier HiPatriot Hi1018 as a SoC display controller. No datasheets
available, but I suppose it will not accept digital data from a
microcontroller, just pictures and movies from a memory card.
My idea was: Leave the controller and driver electronics intact, just
use the HSTART, VSTART, VCOM and PixelClock pulses delivered by the
Hi1018 to generate the frame content which is fed to the analog drivers.
I just had to cut the analog RGB signal path from the Hi1018 by removing
3 coupling capacitors. See youtube video for a demo:
I made up a small VHDL implementation (about 40 lines of code, see
attachment) for a proof of concept (bouncing ball demo, monochrome for
simplicity). The interface to my FPGA consists of only 6 wires (2 more
for color display). The image is sharp and clear (pixel-to-pixel