Raspberry Pi 4

wicki wrote: >
now a period of 80.000 ist possible.

What is a possible, usable step-rate?

I'm not sure what you are measuring yet. Are you measuring all the duration of all the intervals between pulse edges falling and rising, just rising or just falling or?

When we get around to building a proper preempt_rt kernel for the pi4 the services you mask will be turned off as well as the cpu core freq be maxed out (as spma posted above).

All this should be done when properly building the preempt_rt kernel. Working on optimizing GPIO pulse generation before you have a good preempt_rt kernel is going to waste lots of effort.

What do you mean by proper preempt rt kernel?
Is that something else than the rpi-4.19.y-rt from github.com/raspberrypi/linux ?

PCW wrote: Thanks for posting that
Its nice that the RPI4s SPI hardware is compatible with the
RPI3's and only needs a different base address.

Have you tried mesaflash on the RPI4? I does work on the RPI3 though the
syntax is not obvious...

github.com/jethornton/mesaflash has some added SPI help text and
support for about 6 new boards including the RPI3/4 compatible 7C80/7C81

...slightly strange and light on error messages indeed... Yes it seems to work if I reboot with spi enabled. I did not try anything more advanced than a readhmid yet. Is this the latest official version?


/svante

They didn't do the best job of configuring the preempt_rt kernel posted there.

NTULINUX did the majority of the RTAI that works the past few years. He will likely post a better config for LinuxCNC use github.com/NTULINUX/RTAI

We just got our pi4 yesterday.