Raspberry Pi GPIO Performance? (I want to design a driver board)

The guy using DMA
github.com/Nikolay-Kha/PyCNC

and a driver board for pi's and lcnc
github.com/ChrisWag91/PI-LCNC

i'm really fed up with any breadboarding ( any plug in wiring )
I would like to get one of Chris's level shifters but will use the more common
4way bi-dir pcbs that i have. I use the 3.3v to 5v for driving stepper divers
( TB6560 TB6600 DRV8825 AD8???? G540 ) because they just work better,
Desptie claims that 3.3V control signals are fine for G540 et al, i find otherwise.
grumble ends
let us know what you do about drivers and rpi.
Was the 4G mem problem (no usb ) fixed on the rpi 4 yet?
I just looked and it seems the fix is up to users applying patches
( meaning no distro has fix already afaict)
ttul8r
tomp

I also want to use FPGA as the driver board, but I can't buy mesa driver board in China. I saw this picture recently. Do you have more information about this picture 

meo_udon post=192420 userid=28441用于 Rpi 的 DIY 7i90SPI 很容易。

tuzki wrote:

I also want to use FPGA as the driver board, but I can't buy mesa driver board in China.

Have you seen:  forum.linuxcnc.org/27-driver-boards/44422-colorcnc?start=0