CFAX12864T1 Refresh Speed?


New member
I'm new to LCDs and somewhat green on embedded development in general. I'm intending to use the CFAX12864T1 display for a small, handheld measurement device. I haven't made a final MCU selection, but I'm considering TI's MSP430 series, STM's STM32 series, Freescale's MCF522xx ColdFire V2, and Atmel's XMEGA. I have a couple of sample displays and the CFAXZIF-DEMO board, which I successfully got working with an old PC.

The display looks great, but something I've noticed with the CFAXZIF-DEMO / PC setup is that the display refresh appears really slow. When I press any of the eight demo buttons (Image, Logo, Stripes, etc.), it takes probably a full second or so to draw the new image to the screen. (Maybe less; I didn't time it. It's visibly slow, though.)

Is this representative of the performance I'm likely to see with an MCU in a "real" system? Or is this simply a limitation of the PC's parallel-port speed, or the way the demo app is coded, etc.?

Also, is there a significant performance difference between the controller's parallel and SPI interfaces?

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CF Tech

The slow update speed is just an artifact of the test setup. On individual machines it can go much faster, but that made it not work on other machines.

One drawback of SPI is that you cannot read the screen. Other than that, you would just have to look at the transfer time, number of port pins, simplicity of code, etc.

Typically it works out better to have a frame buffer allocated in the processor's memory. Do all your image manipulation (text, lines, etc) in that, then when you are ready to update the new frame to the user, it should only take maybe 10mS to transfer the data from the frame buffer out to the physical display.