Serial backpack for 320x240

J. Mark Wolf · Post by **J. Mark Wolf** » Tue Dec 13, 2011 1:58 pm

I'm considering buying and learning Swordfish in order to develope a "serial backpack" board for quarter-VGA (320x240) LCD panels. I see that S. Wright and others have graciously provided sample Swordfish code.

I've been using a serial backpack board that I developed for the Toshiba T6963 LCD controller on a 160x128 pixel LCD, for several years now that has worked well for me, but now I would like a larger format and higher resolution, with touchscreen perhaps.

I looked on the web for serial controller interface chips but haven't found anything that suits my fancy.

Crystal Fontz has a nice selection of monochrome, daylight-readable displays.

But I'm finding references to annoying update flicker on some of these displays. Can anyone comment on this, and other gotcha's on these LCD's before I go investing in compilers and LCD panels, and PCB boards?

rmteo · Post by **rmteo** » Tue Dec 13, 2011 3:09 pm

Are you thinking of doing a TFT (color) or STN (monochrome) 320x240 display? I have done (commercially) a serial backpack for 128x64 to 240x128 monochrome displays using SF.

I would recommend something with more grunt than any PIC18 - especially if your are wanting to go with TFT and touch-panel. Here is an example of of a TFT (with serial backpack and touch-panel) µLCD-32PT(GFX) - it is available for $85 here. AFAIK, they use a 16-bit dsPIC33 at 40-60MIPs. Given their price, performance and availability, I would go with a 32-bit ARM processor today.

J. Mark Wolf · Post by **J. Mark Wolf** » Tue Dec 13, 2011 7:16 pm

Thanks for the info, but I'm looking for something on the order of 5" to 5.7" diagonal monochrome.

This will be going in an experimental aircraft instrument panel, and can't be one of the real small LCD's that are common nowadays.

Color would be cool, but I suspect that daylight visibility would be a problem.

What I think I have in mind is an LCD with a built in S1D13700, with a serial interface and and some smarts to make it easy to draw boxes and circles, and buttons, etc.

rmteo · Post by **rmteo** » Tue Dec 13, 2011 7:45 pm

As I mentioned above, I did a serial backpack for a 240x128 GLCD (T6963, similar to the one below) some years back. Diagonally, it measures about 5in.

Alstonn · Post by **Alstonn** » Wed Dec 14, 2011 12:01 pm

rmteo wrote:As I mentioned above, I did a serial backpack for a 240x128 GLCD (T6963, similar to the one below) some years back. Diagonally, it measures about 5in.

I think it's great achievement and i appreciate to you. Well done and i hope in future you also work from the same passion.

J. Mark Wolf · Post by **J. Mark Wolf** » Wed Dec 14, 2011 12:38 pm

Yes I'm familiar with that LCD, almost bought it. It's quite a a bargain considering the serial I/O and micro SD card interface, multicolor backlight, touchscreen, etc, etc.

But the actual dimensions of the viewable area are significantly smaller than my 160x128, at least on the Y-axis, so it doesn't fill the opening I have in my panel very well.

What feature set does your serial back pack offer?

rmteo · Post by **rmteo** » Wed Dec 14, 2011 2:44 pm

I am not recommending that specific GLCD - more like this one http://www.crystalfontz.com/product/CFAG240128D-TMI-TZ

My serial backpack does things like different size/font text, icons/sprites, lines, circles, rectangles, bitmap display, etc. This is for the 128x64 but the one for the larger display is similar.

A serial backpack saves I/O pin usage and makes it easier for one to use a GLCD. However, it would be more efficient to drive the GLCD directly, especially in situations like yours - I wouldn't bother with the serial backpack.

J. Mark Wolf · Post by **J. Mark Wolf** » Wed Dec 14, 2011 6:35 pm

rmteo

Is you backpack commercially available somewhere, or was it a one-off for yourself?

rmteo · Post by **rmteo** » Wed Dec 14, 2011 6:51 pm

The 240x128 was a custom for a customer. Today I work with TFT exclusively. For small (handheld) applications they are great - and actually cost quite a bit less than GLCDs.

For larger displays, I use something like this as a front end to the application:

For less than $70 you get 800MHz Processor, 2GB Flash, 256MB RAM, 7in. 800x480 TFT with touch screen, Camera, Micro-SD, USB, WiFi, etc.

J. Mark Wolf · Post by **J. Mark Wolf** » Thu Dec 15, 2011 2:32 pm

Thanks for the dialog guys.

Senacharim · Post by **Senacharim** » Thu Dec 15, 2011 2:49 pm

rmteo wrote:For less than $70 you get 800MHz Processor, 2GB Flash, 256MB RAM, 7in. 800x480 TFT with touch screen, Camera, Micro-SD, USB, WiFi, etc.

A link please!! I'd be quite interested in playing with that platform...

rmteo · Post by **rmteo** » Thu Dec 15, 2011 3:32 pm

http://www.ebay.com/itm/270853740118?ss ... 1423.l2648

Direct from manufacturer cost is as low as $42/each.

RangerBob · Post by **RangerBob** » Thu Dec 15, 2011 4:03 pm

Ah yes, my Boss spotted one of these on Ebay and decided they would be great to give to customers instead of our current expensive iPads.

I'll just leave this here:
http://arstechnica.com/gadgets/reviews/ ... tablet.ars

I concur with ars.

Senacharim · Post by **Senacharim** » Thu Dec 15, 2011 4:16 pm

Hmm. Maybe if a cunning owner of a JTAG who knows how to cross-compile code for an ARM processor were to replace the OS with something else...

RangerBob · Post by **RangerBob** » Thu Dec 15, 2011 4:27 pm

It's not the OS that's really the issue. The hardware is atrocious.

The one I had to evaluate lasted maybe 20 minutes on battery.
If you left it charged overnight, it was flat by morning.
The screen is softer than butter and scratched badly within 20 minutes due to the dry skin on my fingers.
The screen is unresponsive, you have to push really hard to get it to register, then the OS *might* do something.
I managed to type in an email subject line without error once, that was as far as I was willing to test typing.
The chassis flexes easily and pops the bezel out.
Even the UK mains charger wouldn't fit properly in half the sockets in the office. I had to plug it into an extension strip!

On the plus side, it had Angry Birds pre installed! (but it ran like molasses).

Read to Ars article. Its funny and very true!