Hello!
I am unable to post in the Technical Support forum, so I post here. Moderators can move the thread at will.
I am developing a product with the CFAG320240CX-TFH-T-TS display, and an AT91SAM7S256 as the system processor. They are connected through a Fairchild 74LVXC3245 level shifter like this:
AT91SAM7S256(3.3V) ==> 74LVXC3245 ==> CFAG320240CX-TFH-T-TS(5V)
I have added resistors (82 ohms) on the outputs of the level shifter to reduce the ringing on the LCD signal lines. Helped a bit, but did not eliminate the problem.
Initialization, text and bitmaps are working like a charm.
Configuration:
6800 mode, as shipped. R/W is hardwired low, DISPOFF is hardwired high. JF1 and JF2 are mounted, grounding the bezel and mounting holes. I am using Screen Block 1 for text, starting at address 0x0000 and Screen Block 2 for graphics, starting at address 0x04B0. I have mounted decoupling capacitors on the LCD module, 0.1µF ceramic and 330µF tantal polymer electrolytic.
Touch panel: all 4 wires grounded. Tried leaving them floating, no change.
Graphics test:
Write 0xFF ==> wait 50ms ==> write 0x00 ==> wait 50ms
repeated in an infinite loop. This results in an all-black/all-white screen alternating at 10Hz.
Attached is an image from my logic analyzer showing the first few transitions of the test.
Text test:
Write 'A' ==> wait 50ms ==> write 'B' ==> wait 50ms
repeated in an infinite loop.This results in an all-A/all-B screen alternating at 10Hz.
The problem:
The graphics test will fail after a seemingly random delay of 1-10 seconds, rendering the display with a single black horizontal line with some 'bleeding' outside the display active area. Looks like DC on the panel, not good.
If I increase the write interval, it takes longer before the display crashes.
The strange thing:
Text test does not fail.
That leads me to believe my hardware is OK.
The question:
Has anyone successfully updated graphics on this display, at any rate, over any amount of time?
I am beginning to doubt this is possible, but I would be very happy to be proven wrong.
Any suggestions or ideas are most welcome.
Regards,
Thomas Strand
I am unable to post in the Technical Support forum, so I post here. Moderators can move the thread at will.
I am developing a product with the CFAG320240CX-TFH-T-TS display, and an AT91SAM7S256 as the system processor. They are connected through a Fairchild 74LVXC3245 level shifter like this:
AT91SAM7S256(3.3V) ==> 74LVXC3245 ==> CFAG320240CX-TFH-T-TS(5V)
I have added resistors (82 ohms) on the outputs of the level shifter to reduce the ringing on the LCD signal lines. Helped a bit, but did not eliminate the problem.
Initialization, text and bitmaps are working like a charm.
Configuration:
6800 mode, as shipped. R/W is hardwired low, DISPOFF is hardwired high. JF1 and JF2 are mounted, grounding the bezel and mounting holes. I am using Screen Block 1 for text, starting at address 0x0000 and Screen Block 2 for graphics, starting at address 0x04B0. I have mounted decoupling capacitors on the LCD module, 0.1µF ceramic and 330µF tantal polymer electrolytic.
Touch panel: all 4 wires grounded. Tried leaving them floating, no change.
Graphics test:
Write 0xFF ==> wait 50ms ==> write 0x00 ==> wait 50ms
repeated in an infinite loop. This results in an all-black/all-white screen alternating at 10Hz.
Attached is an image from my logic analyzer showing the first few transitions of the test.
Text test:
Write 'A' ==> wait 50ms ==> write 'B' ==> wait 50ms
repeated in an infinite loop.This results in an all-A/all-B screen alternating at 10Hz.
The problem:
The graphics test will fail after a seemingly random delay of 1-10 seconds, rendering the display with a single black horizontal line with some 'bleeding' outside the display active area. Looks like DC on the panel, not good.
If I increase the write interval, it takes longer before the display crashes.
The strange thing:
Text test does not fail.
That leads me to believe my hardware is OK.
The question:
Has anyone successfully updated graphics on this display, at any rate, over any amount of time?
I am beginning to doubt this is possible, but I would be very happy to be proven wrong.
Any suggestions or ideas are most welcome.
Regards,
Thomas Strand
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