[sdiy] Fast lcd display like digitakt

sleepy_dog at gmx.de sleepy_dog at gmx.de
Sun Jun 16 16:21:11 CEST 2024


Note that the STM32 2D accelerator stuff requires use of their closed
source library software, as the HW is /undocumented/.

http://efton.sk/STM32/gotcha/g207.html


> On Sun, 16 Jun 2024, 13:48 Benjamin Tremblay via Synth-diy,
> <synth-diy at synth-diy.org> wrote:
>
>     Thanks Brian!
>
>     Benjamin Tremblay
>
>     > On Jun 15, 2024, at 11:49 PM, brianw <brianw at audiobanshee.com>
>     wrote:
>     >
>     > I am not a particular fan of ST Micro (*), but they have a
>     great line of processors that can directly drive parallel LCD modules.
>     >
>     > Look at the STM32F series. I recall that there are evaluation
>     boards, but I'm not sure where mine got to in the pile of old demo
>     boards.
>     >
>     > The bus can handle at least 24-bit width, but you might end up
>     only needing an 8-bit parallel LCD module. In addition to treating
>     the LCD like fast memory, these chips also have 2D accelerators in
>     the processor that can convert bit depth and colors when blending
>     resources in memory to the display. For example, you could have
>     1-bit fonts in memory, to save space, but then put the LCD in
>     8-bit color or 4-bit color mode and have the 2D accelerator handle
>     the format conversion in hardware. I think ST calls this the "ART
>     Accelerator" (Adaptive Real-Time Accelerator).
>     >
>     >
>     https://www.st.com/en/microcontrollers-microprocessors/stm32f4-series.html
>     >
>     > The catch is that you'll have to graduate from the hobby
>     developer environments and write your own bare metal or RTOS
>     firmware. That is a big step, but it's usually the only way to get
>     maximum performance anyway.
>     >
>     > * I have nothing against ST Micro, per se. There are just so
>     many ARM choices out there, and I've already got my favorites.
>     That said, when something they specialize in is needed, I wouldn't
>     hesitate to use ST.
>     >
>     > I worked on a project where a single STM32F40x was driving 27
>     color LCD displays. Yep, twenty-seven of them, and the updates
>     were plenty fast.
>     >
>     > Brian Willoughby
>     >
>     >
>     >> On Jun 15, 2024, at 7:36 PM, Benjamin Tremblay wrote:
>     >> Nope, I made an error. Wasn’t really using spi. Now it runs better.
>     >> I do think I want to find a larger monochrome display.
>     >> Benjamin Tremblay
>     >>
>     >>> On Jun 15, 2024, at 8:54 PM, Benjamin Tremblay wrote:
>     >>> I’ve been working on some virtual synth code, and also
>     learning how to send nrpn midi messages. It’s all going well but
>     for midi controller and synth projects I envision a paged Oled
>     display with virtual knob animation and maybe a touchscreen.
>     >>> What kind of hardware do I need for this? I purchased 2” and
>     3” displays from Amazon and tried out sample code on an arduino
>     mega and then ran it on a Teensy LC.  I have a teensy 4 and a pico
>     and some Stm32F401 boards.
>     >>> I am using the Adafruit gfx library and so far using an
>     offscreen canvas is too slow.
>     >>> Should I use a 1-bit display? Repainting the screens is
>     sluggish; maybe 2fps max. Should I use a faster SPI
>     implementation? I know teensy LC is slow. Should I use another
>     graphics library?
>     >>> I’m going to assume displays are nice for things like waveform
>     editing and such. I have seen some fast oscilloscope demos on Oled
>     displays.
>     >>> Hm.
>     >>>
>     >>> Benjamin Tremblay
>     >
>
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