Raspberry Pi and GTT480272A-USB

GTT TFT Support

Moderator: Mods

Post Reply
chpwssn
LCD?
Posts: 5
Joined: Wed Oct 17, 2012 8:59 am
Location: Fort Collins, Co, USA
Contact:

Raspberry Pi and GTT480272A-USB

Post by chpwssn » Wed Oct 17, 2012 9:11 am

Hey everyone, we just started working on integrating a Raspberry Pi and the Matrix Orbital GTT480272A-USB into one of our products and I was curious if anyone had suggestions on using the display with Linux and such?

Once we get it all figured out I could write up what we did and post it here if anyone is interested.

Clark
Matrix Orbital
Matrix Orbital
Posts: 861
Joined: Fri Aug 17, 2007 10:58 am
Location: Matrix Orbital
Contact:

Re: Raspberry Pi and GTT480272A-USB

Post by Clark » Wed Oct 17, 2012 2:51 pm

Hey chpwssn,

The USB version of the GTT may require some driver setup which you can learn more about here. Once you have it connected to a virtual serial port, the command protocol is pretty straightforward.

If you could let us know some of the functions or features of the product I'm sure the community would be able to provide some ideas.

Thanks,
Troy
Troy Clark
Design & Development
Matrix Orbital

chpwssn
LCD?
Posts: 5
Joined: Wed Oct 17, 2012 8:59 am
Location: Fort Collins, Co, USA
Contact:

Re: Raspberry Pi and GTT480272A-USB

Post by chpwssn » Thu Nov 08, 2012 8:20 am

Is there a way to use the i2c header on the USB model for development? The Raspberry Pi has native i2c and can't provide enough power through it's USB hub to power the GTT.

Clark
Matrix Orbital
Matrix Orbital
Posts: 861
Joined: Fri Aug 17, 2007 10:58 am
Location: Matrix Orbital
Contact:

Re: Raspberry Pi and GTT480272A-USB

Post by Clark » Thu Nov 08, 2012 1:39 pm

Hi chpwssn,

A USB version of the GTT can be made to operate using the I2C interface, but it will require modifications that will void the warranty of the unit. If you need to use I2C on a USB GTT, here's what to do.

Place 0ohm jumper resistors on the two I2C pads of the protocol select block, do not remove the four USB resistors. Populate a header on the Serial/I2C port, or solder connections directly to it following the pinout in the hardware manual. From a hardware standpoint, the unit will now be in both USB and I2C mode.

Next, ensure that you are running at least firmware revision 1.2.0, if you are unsure you can download the latest firmware here. Again, you can still use the mass storage header, and at this point will still be able to communicate to the unit using the USB header as well.

Finally, save a file named I2C.cfg to the root folder of GTT memory containing the desired I2C write address, I have attached the default (0x50) below. When this file is present, the GTT will respond to the I2C port; without it the unit will be a standard USB model.

Troy
Attachments
I2C.zip
Default I2C configuration file.
(114 Bytes) Downloaded 152 times
Troy Clark
Design & Development
Matrix Orbital

chpwssn
LCD?
Posts: 5
Joined: Wed Oct 17, 2012 8:59 am
Location: Fort Collins, Co, USA
Contact:

Re: Raspberry Pi and GTT480272A-USB

Post by chpwssn » Wed Jan 09, 2013 10:10 am

Hey guys, got the I2C communicating and working fine, quick question: Is there a command that will clear the reply buffer? If a user gets carried away with a shutdown touch region, the buffer fills up and they end up starting up and immediately shutting down because the reply buffer still has a couple of the touch region replies in it.

Clark
Matrix Orbital
Matrix Orbital
Posts: 861
Joined: Fri Aug 17, 2007 10:58 am
Location: Matrix Orbital
Contact:

Re: Raspberry Pi and GTT480272A-USB

Post by Clark » Thu Jan 10, 2013 8:51 am

Hi chpwssn,

Unfortunately, the GTT does not have a clear buffer command for I2C. But there are a number of different features we might be able to use to solve this problem.

It sounds like you have created a touch region that shuts down either an external piece of hardware, which make take a length of time, during which a user might try to encourage the system to move a little faster by pushing that shut down button a few more times. You might try sending a beep when that button press is read, and maybe even putting your code into a loop that reads touch responses until something other than a shut down value arrives.

If you can't see a solution using the commands in the manual, let me know a little more about what behaviour you'd like to see from the GTT and I might be able to provide some additional insight.

Thanks,
Troy
Troy Clark
Design & Development
Matrix Orbital

chpwssn
LCD?
Posts: 5
Joined: Wed Oct 17, 2012 8:59 am
Location: Fort Collins, Co, USA
Contact:

Re: Raspberry Pi and GTT480272A-USB

Post by chpwssn » Fri Jan 11, 2013 10:38 am

Thanks Troy, I think I'll just put in a loop right before it fully shuts down to just "dump" the memory by reading it a ton of times

Clark
Matrix Orbital
Matrix Orbital
Posts: 861
Joined: Fri Aug 17, 2007 10:58 am
Location: Matrix Orbital
Contact:

Re: Raspberry Pi and GTT480272A-USB

Post by Clark » Fri Jan 11, 2013 11:30 am

No worries chpwssn, I appreciate your feedback and see the importance of that feature. I was surprised to see we didn't implement something similar to the Clear Key Buffer command for the GTT and will make a request for the next revision.
Troy Clark
Design & Development
Matrix Orbital

chpwssn
LCD?
Posts: 5
Joined: Wed Oct 17, 2012 8:59 am
Location: Fort Collins, Co, USA
Contact:

Re: Raspberry Pi and GTT480272A-USB

Post by chpwssn » Wed Jan 16, 2013 11:56 am

Cool, I'm also having trouble with the AUTOEXEC file. Whenever I implement it, it simply prints the contents to the screen. The way I made it was by first typing all the commands (in my case loading all my bitmaps to their indexes) into a text editor, non separated on one line and moving that to the root directory on the SD card. Then I tried putting the commands in and generating the file via a Hex editor and had the same result: the screen would power on, do the splash screen and then proceed to print out the entire contents of the AUTOEXEC file to the display without loading the bitmaps to the indexes. I'm probably just not creating it correctly, I attached both versions of my files to this post. I added a .txt extension so I could upload it, I have it on the GTT with no extension.

Thanks
Attachments
AUTOEXECtext.txt
Text editor version of the file
(1.84 KiB) Downloaded 146 times
AUTOEXEC.txt
Hex editor version
(673 Bytes) Downloaded 147 times

Clark
Matrix Orbital
Matrix Orbital
Posts: 861
Joined: Fri Aug 17, 2007 10:58 am
Location: Matrix Orbital
Contact:

Re: Raspberry Pi and GTT480272A-USB

Post by Clark » Wed Jan 16, 2013 10:27 pm

Hi chpwssn,

You're exactly right, neither file is quite right.

If you plan on building your own autoexec files, grab a binary text editor such as HxD. Then take a look at the short example attached which loads a bitmap named "Base.bmp" to index 0.

The easiest way to create an autoexec file is actually in the [url=http://www.matrixorbital.ca/software/GTT/GTT Support Tool[/url]. Just build a list of commands then save the file, making sure you select the .bin file type. The program will still add a .gsf file extension, but remove it and transfer the file over to your GTT and you should be in business.

Troy
Attachments
autoexec.txt
Sample AutoExec File
(12 Bytes) Downloaded 140 times
Troy Clark
Design & Development
Matrix Orbital

Post Reply

Who is online

Users browsing this forum: No registered users and 1 guest