Raspberry Pi 4

I just built an RPi4 image using John Thornton's guide. Works well as expected ... 50uS max latency w 4glxgears after 16hrs. But the recipe gets you 2.8.1, a little confusing but easy to adapt. Should/Can we substiture 2.9 in "git checkout 2.8" ?

Also the gpio driver from MX_Master has the reset function, allowinfg doubleStep for the OrangePi that he targeted. Can this code be adapted for RPi ?

I have not read all 47 pages of postings but wanted to jump in here. I have a modified version of PICnc-V2 running on the Pi4. I think it can get the rates you are looking for. In my testing I see the linuxcnc 2.9.0 is generating motion commands at startup. Very small but the machine is in estop. If you run the stock gcode and stop the machine with the power or estop switch the system continues to generate motion at what ever velocity it was at when you stopped. Very dangerous. Thankfully the only thing I have connected is test equipment.

@ Bari
i did not try raising servo thread ( 1000us to 2000us)
Same base but servo at 1000 was _not_ 50uS or less, so ,
Thx for the idea. tomp

re 2000uS servo thread
I have success with soft stepper 75uS base 1000uS servo
but latency is too bad with servo 2000, so
my best effort is 75uSbase 1000 servo. My 1.5mm screw and 200 setp/rev
motors gets me 50 steps/sec 3meters per min without doublestep.
I am working on hal_pi_gpio to get inverted pins and reset pins.
That woul allow my RPi3 6meters /min software stepping.
Its reliable, I have been running a 3Dchips modified to loop 100 times. Its run many times now over 3 days, no UXRTdelays.

tomp

Hello Andy
re: #158377
I have been studying hal_parport hal_pi_gpio and opi_gpio
to see how gpio drivers handle user instancing and
how the program stores the states of pins.

I am headed down this road:
That would create 3 32bit stores , one each for direction, exclusion, and reset-ability.

I have no provision for pullup pull down or open collector/tristate ,
because I think users can use external resistors as they like
and I avoid the OC issue due to cowardice. ( not important imo ).

So, instead of the trplets stored right now describing 10pins , inside 3 32bit memories
there would be simpler 3 32 bit-fields describing the 3 features
very easy to see with a fixed font.

Also I will add the missing invert pins to all inputs in the dir parm.

any thoughts?
thx
Tomp

How about a single 32 element string, containing letters? R = output / reset I = in, O = out...