Rpi4 HAL question

Hello,

I am a beginner of LinuxCNC and trying to set up a machine with Rpi4 and prefer to use its GPIO for pulse generator just for my understanding LinuxCNC architecture.
I installed 
www.linuxcnc.org/iso/linuxcnc-2.8.1-pi4.zip
and
github.com/LinuxCNC/linuxcnc/blob/master...hal_pi_gpio_demo.hal
.
The hal_pi_gpio_demo.hal works and I confirmed each axis step pulses are generated.

In the file, there is a line that I cannot understand, which is 
loadrt hal_pi_gpio dir=78855 exclude=32918520
.
I understand loadrt hal_pi_gpio, but do not dir=78855 exclude=32918520.
Could anyone please explain what the numbers mean?

Thank you

Cato 

What does the manual page for hal_pi_gpio say?

I suspect those numbers are masks that set which GPIO pins are outputs (dir)
and which GPIO setup bits to leave unchanged (excluded)

The numbers would make more sense in hexadecimal

CatoFu wrote:

Hello,

I am a beginner of LinuxCNC and trying to set up a machine with Rpi4 and prefer to use its GPIO for pulse generator just for my understanding LinuxCNC architecture.
I installed 
www.linuxcnc.org/iso/linuxcnc-2.8.1-pi4.zip
and
github.com/LinuxCNC/linuxcnc/blob/master...hal_pi_gpio_demo.hal
.
The hal_pi_gpio_demo.hal works and I confirmed each axis step pulses are generated.

In the file, there is a line that I cannot understand, which is 
loadrt hal_pi_gpio dir=78855 exclude=32918520
.
I understand loadrt hal_pi_gpio, but do not dir=78855 exclude=32918520.
Could anyone please explain what the numbers mean?

Thank you

Cato 

Look this post
forum.linuxcnc.org/27-driver-boards/3770...erry-pi-gpios#157180

Hello PCW,

Thank you for your help.

Now I understand what the number means.
As you mentioned there are some lines which commented out on the file.
It says;
# 0 0 0 0 0 0 0 0 0 1 0 0 1 1 0 1 0 0 0 0 0 0 0 1 1 1 dir mask (0 means in 1 means out) dec 78855
# 0 1 1 1 1 1 0 1 1 0 0 1 0 0 1 0 1 1 1 1 1 1 1 0 0 0 exclude mask (0 means use 1 means dont use) dec 32918520

I did not even know what the dec means and now I have leaned.

Thank you so much!
Have a good day!

Cato

Write software, you can try

download