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STR75x and TFT display

I have to drive a TFT display with an ARM7 ST MCU (STR750 family). The application must show some color images (8 bit per color) on a

320x240 QVGA.

The choosen MCU has up to 256KB internal flash and 16KB internal RAM. I plan to add one external serial flash (ST serial flash connected to the MCU's SMI interface) and maybe an external RAM (always ST product).

The TFT is a 12 bit-depth color TFT and has to be driven with an external clock @ 6.5MHz in order to obtain the classical 50Hz refresh rate. Specs says that each pixel must be presentet to TFT pin every 154ns.

One possible solution is to read each pixel value directly from the FLASH memory, presenting it to TFT pins as soon as possible: but I'm worried about external FLASH accessing and elaboration time, outputs must be ready in 154ns. With this solution I can omit the external RAM with it busses (something like 30 wires @20MHz minimum).

The second solution uses external RAM to create a double buffered software architecture: each time I have to change the image, I load the back buffer from FLASH then I swap these buffers. TFT inputs are read from RAM.

Now I have some questions:

  1. STR750 clock is driven by an external oscillator @ 4 (or 8) MHz, then with the internal PLL I can obtain PLL_CLOCK up to 64MHz: there's a "normal" PLL range or I have to calculate it based on timimgs?

  1. Is there any better solution to the problem?

  2. Where can I find info about TFT driving?

Thanks!

Reply to
djordj
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Why dont you try to get a camel through a needle eye as well :-)

Use an MCU chip with a build in TFT LCD controller?

AT91SAM9261 can read a serial (Atmel) flash at 33 Mbps into its internal QVGA framebuffer. At 8 bit per pixel, you can double buffer the display inside the internal SRAM. If you insist on having the nasty ST part, then interface it through any of the fast serial ports or USB, but you'd be better of skipping it altogether.

--
Best Regards,
Ulf Samuelsson
ulf@a-t-m-e-l.com
This message is intended to be my own personal view and it
may or may not be shared by my employer Atmel Nordic AB
Reply to
Ulf Samuelsson

Why dont you try to get a camel through a needle eye as well :-)

Use an MCU chip with a build in TFT LCD controller?

AT91SAM9261 can read a serial (Atmel) flash at 33 Mbps into its internal QVGA framebuffer. At 8 bit per pixel, you can double buffer the display inside the internal SRAM. If you insist on having the naSTy ARM7 part your were thinking of, then interface it through any of the fast serial ports or USB, but you'd probably be better off, skipping it altogether.

--
Best Regards,
Ulf Samuelsson
ulf@a-t-m-e-l.com
This message is intended to be my own personal view and it
may or may not be shared by my employer Atmel Nordic AB
Reply to
Ulf Samuelsson

Can you explain me some more details, please?

Thanks.

PS: do you have a valid mail?

Reply to
djordj

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