info on single 32bit write to io port

mkefalas · ‎2009-02-16

Posted on February 16, 2009 at 20:40

mkefalas · ‎2011-05-17

Posted on May 17, 2011 at 13:03

Thanks jj

Is a cpld combination cheaper than a FMSC equiped device ?.

What CPLD have you used?.

I have one LCD but ,although 8080 bus compliant, uses 18 bits

single cycle write and two cycles 16 bit mode (plus shifts).

So i would like to avoid two write cycles .

jj · ‎2011-05-17

Posted on May 17, 2011 at 13:03

If you choose a ''non-FSMC'' device you are limited to a 16 bit width.

To control a color, TFT Lcd we needed a 16 bit data bus plus various control signals & strobes. Our solution was to choose 12 bits from a port - and then perform ''back to back'' writes/reads to a CPLD we placed between the micro & TFT. Within the CPLD we created ''automatic strobes'' which yielded the fastest transfer with least software overhead...

mkefalas · ‎2011-05-17

Posted on May 17, 2011 at 13:03

Hi

I'm new to the STM32 .As is see the ouput ports are 16 bit wide.

I need to address memory with 20 address lines .I don't want to use

the memory interface some parts have .Is it possible to write a single

32 bit word to an output port in a single command ?. I don't want to write 16bit lo-address and then 4 bit for the rest of the adress lines.

Any help would be appreciated.

jj · ‎2011-05-17

Posted on May 17, 2011 at 13:03

Hi back,

Our study showed our best value resulted from non-FSMC STM32 and our low cost, special CPLD. (developed between major University & my firm) By this means we can gain better volume discount with STM32 - and selectively ''fit'' our CPLD.

I've been in displays for quite awhile - haven't found it home to best/brightest. (just try to get tech support - or a data sheet which hasn't been scanned into illegibility) 18 bit data (6-6-6) seems SO wasteful. (transfer 1st 16 bits, then a 2nd transfer of 2 bits - plus further strobes)

Suggest that you consider 16 bit data (5-6-5) but then you require CS, WR, and at least 1 Adr. bit. Now you see why we chose TWO - back to back 12 bit transfers. Taking ALL 16 bits from an STM32 ''exhausts'' ALL of that port - in our case we elected to keep the RTC - which would have been lost if we used all 16 bits - and we still would not have satisfied strobes/control requirement!

We will be introducing a new family of economical, extreme contrast TFTs ranging from 2.4 - 8.0'' - all with the ''same'' interface: SPI, I2C, Uart or 8 bit parallel. You may select a version with a pre-programmed STM32 -or buy just the raw display. Good luck with your project.