Raspberry Pi 4

Hi team, I followed JT's guide on RPi4 build on his uspace site and it completed without fuss albeit the poor wee cpu gets pretty hot during the building compilking activity.

And I have a basic gpio based hal file using the following.....

loadrt hal_pi_gpio dir=78855 exclude=32918520

# beware gpio 21 and 22 are still reversed, they control rpins 15&50 and are backwards almost everywhere in rpi docs
# easy to see and check with 'show pins hal_pi_gpio*

# tjp chg to 3 step dir types,plan on using gekco G540
# was loadrt stepgen step_type=5 ctrl_type=v
# make posn loop type
loadrt stepgen step_type=0,0,0

#net estop-out => parport.0.pin-01-out
net estop-out <= iocontrol.0.user-enable-out
net estop-out => iocontrol.0.emc-enable-in


# --- begin addf s
addf hal_pi_gpio.read base-thread
addf stepgen.make-pulses base-thread
addf stepgen.capture-position servo-thread
addf motion-command-handler servo-thread
addf motion-controller servo-thread
addf stepgen.update-freq servo-thread
addf hal_pi_gpio.write base-thread
# --- end addf s


# i use GPIO 2,3,4 for xtep ystep zstep, thats rpin 3,5,7 resp
net xstep stepgen.0.step => hal_pi_gpio.pin-03-out
net ystep stepgen.1.step => hal_pi_gpio.pin-05-out
net zstep stepgen.2.step => hal_pi_gpio.pin-07-out

# i use GPIO 14,15,18 for xdir ydir zdir, thats rpin
net xdir stepgen.0.dir => hal_pi_gpio.pin-08-out
net ydir stepgen.1.dir => hal_pi_gpio.pin-10-out
net zdir stepgen.2.dir => hal_pi_gpio.pin-12-out

I am trying to scope the pins with my oscilloscope and i am seeing no action.

my goal is to evaluate this against my current mach3 system and see how they compare

any thoughts much appreciated. Thanks to the team who are behind this amazxing project.

cheers
Richard

I'd recommend that a common kernel config and version should be used for preempt_rt on the Rpi's and the governor and scaling should also be at some consistent setting. Most users won't see the big picture and not understand why their system doesn't work properly unless the have an exact script to follow. Even then we have seen that most issues with building RTAI, preempt_rt and Linuxcnc are due to mistakes made with the tool chain or setting up the compile.

One of the first things to do with the Rpi4 before even installing any software is getting a proper case with heatsinks and/or cooling fans. The Rpi4 is not a complete single board computer unless its core speed is set very low since it requires a heatsink similar to most x86 PC's to run anywhere close to its top core speed. x86 CPU's used to come with the warning that a heatsink is required for operation. The Rpi4 should come with the same warning/recommendation.

@ gtt38

m.aliexpress.com/item/4000141655235.html is the link to the FPGA board that worked for me.

I didn't see any protection for all the IO's on that board. It gets you lots of gates and unprotected IO, so you'll still need another board to get the IO's out to the real world in a machine environment.

Not to hijack this thread but if anyone is interested I've been testing a 64-bit Gentoo image for the Raspberry Pi 4 :
github.com/sakaki-/gentoo-on-rpi-64bit

After I finish building my crosstools on x86 for this I'll likely have a link to working preempt_rt kernels for LCNC and a u-boot image once that gets stable. In case anyone else wants to stay away from Debian/Raspbian.

The best way is to only enable the performance governor.
But you also can set force_turbo=1 under [PI4] in the boot/config.txt. this will force the turbo clock at all times. doesn’t matter what governor is set.