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Driving parallel-interfaced LCD display via DMA - approach?

wb0gaz
Senior

I wish to drive (write output data streams) to a parallel-interfaced LCD display. There would be 8-32 bits of parallel data (tied to MCU GPIO output lines) and a strobe or clock line (also tied to MCU GPIO output line) to cause those bits to be transferred to the display. Whether there is a "ready" indication (from display to MCU) isnt known yet, somewhat dependent on whether there would be such a requirement, and how the MCU could go about honoring the requirement.

I'm looking for guidance on whether I can do the data transfer via DMA, so that the MCU doesn't need to (under programmed operation) write individual bytes/words to GPIO and toggle the clock/strobe line for each (8-16-32 bit) word transferred. Ideally, I'd like to set a start address for the source data (which would be in ram or flash on the MCU) and have the data transfer cause an interrupt only when complete (rather than for each byte/word transferred.)

My question at this point isn't specific to a given target device/part number, however, if there are target device types or capabilities that are more (or less) appropriate for this capability, I'd like to know what to look for.

I've seen mention of "Fast toggle" (example, cited once in RM0091), but no further explanation of what the term applies to.

Thanks for any advice or pointers, and happy to provide any clarifications that could help narrow the request.

11 REPLIES 11
wb0gaz
Senior

Returning to this topic after a long time as implementation is now necessary - I did a search yesterday on the terms "stm32 parallel display gpio". One of the initial results was this document (dated January 2016) from ST Microsystems:

AN4666
Application note
Parallel synchronous transmission using GPIO and DMA

This covers precisely the subject of the original post, and provides a roadmap to implementing the needed solution without FSMC (as I'm using 64-pin device, FSMC/FMC - which would be preferable - is not available.)

Thank you for the informative contributions to my then-speculative query from 2022, which yielded the two candidate directions (FSMC and Timer+DMA).

I wish there was an index (web page, listing, PDF, etc.) of ST Microsystems app notes covering STM32 - evidently there is considerable resource there!

 

 

> I wish there was an index (web page, listing, PDF, etc.) of ST Microsystems app notes covering STM32 -

https://www.st.com/en/microcontrollers-microprocessors/stm32-high-performance-mcus/documentation.html for 'F2/'F4/'F7/'H7; for other super-families, "Documentation" tab for that super-family.

> evidently there is considerable resource there!

Unfortunately, ST decided not to invest into decent appnotes anymore. Lately, more info is posted here as articles by ST staff; but since migration to Khoros, they are not easily filtered.

JW