GTT returning 254 253

GTT TFT Support

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GTT returning 254 253

Post by bryancole » Wed Nov 11, 2015 2:41 am

We have an app driving a GTT43A with v2.0 firmware. Everything runs fine for a couple of hours after openning the USB connection to the device when out-of-the-blue, the device returns [252, 253] following a command [254, 97, 0, 0, 240, 0, 0] (DisplayBitmap, buffer idx=0, X=240, Y=0). What does 252,253 mean? There's no mention of it in the protocol docs. There are other posts on this forum indicating that sending 254,253 to the device kicks the watchdog timer causing a reboot. I can't tell in my app if the 252,253 message directly follows the DisplayBitmap command or if it is being sent unsolicited (like an event). I'm guessing this indicates the internal watchdog timer has fired and the unit is rebooting. Can someone comment?

Associated with this problem is that at about this point, the display of bitmaps gets screwed up and when I try to draw a buffer, the image from a different buffer is shown on the screen. This all points to a firmware bug.



Daniel Divino
Matrix Orbital
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Re: GTT returning 254 253

Post by Daniel Divino » Fri Nov 13, 2015 9:58 am

Hello Bryan,

You are correct. The 254, 253 command is an internal command that will send an interrupt to the Watch dog timer, which is the cause of reset that you are experiencing. In order to solve the issue I want to replicate the circumstances in house. In order to ensure that we are both running the same firmware, can you upgrade your GTT firmware to the current revision

Daniel Divino
Technical Support
Matrix Orbital

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