I wrote a sketch for a Due to receive data via I2C as Master and display on a screen and also on the serial monitor.
Now that I have it the way I need it I wish to supply the Due/shield/Screen via the 12V jack. When I do this the screen lights up and shows the display template as I have it laid out in void setup.
But that is as far as it goes. It does not update with new data from the slave.
If I switch back to the USB power it runs fine. I severed the serial lines in the usb cable so that the only thing the computer supplies is 5V via USB and the sketch runs and the screen updates normally.
The 12 volt power supply is 12V, 1 amp (Triad mfr). My voltmeter says 11.90 open circuit. I also tried a modified computer power supply that has a 12V 10 Amp very clean DC. Same result, only the template shows up.
So I am wondering if anyone has an explanation or had similar trouble trying to supply a Due via the 12V jack?
The 7" display data sheet is here: http://www.datasheet4u.com/datasheet-pdf/Innolux/AT070TN92/pdf.php?id=775300