"djordj" <djordj@despammed.com> wrote in message 
news:mn.b0067d6b0e97bd64.64674@despammed.com...
>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?
>
> 2. Is there any better solution to the problem?
>
> 3. Where can I find info about TFT driving?
>
>
>
> Thanks!
>
>

If you need to connect a tft then choose the STR710 or str9 and use an 
external driver, such as epson or SSD1905/SSD1906 on the external memory bus

I have just used the STR912 and SSD1906 to connect to a Hitachi TX09 TFT 
display.

Regards
Spen

djordj wrote:
> 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.
>

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

> 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?
>
> 2. Is there any better solution to the problem?

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.


> 3. Where can I find info about TFT driving?
>
>
>
> Thanks!

-- 
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

djordj wrote:
> 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.
>

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

> 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?
>
> 2. Is there any better solution to the problem?

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.

> 3. Where can I find info about TFT driving?
>
>
>
> Thanks!

-- 
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

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?

2. Is there any better solution to the problem?

3. Where can I find info about TFT driving?



Thanks!