RPI4 with GPIOs
26 Feb 2020 19:55 #158568
by XMC
RPI4 with GPIOs was created by XMC
Hi everyone,
i'm new to this forum and also new to linuxcnc.
I want to build a hexapod and control it with linuxcnc, but i'm not sure about the hardware.
I've considered to use a Raspberry and the GPIO's instead of a Desktop PC and a Mesa Board for my project (STEP and DIR signal for a a4988 stepper driver, or something similar).
There are some threads about the Raspberry Pi 4 and Mesa cards, but is it also possible to use the GPIO's of the RPI4 for STEP and DIR?
Regarding to the minimum system requirements it should work with the new Raspberry Pi 4, but is it a good idea, or is it recommendable to use a normal PC?
i'm new to this forum and also new to linuxcnc.
I want to build a hexapod and control it with linuxcnc, but i'm not sure about the hardware.
I've considered to use a Raspberry and the GPIO's instead of a Desktop PC and a Mesa Board for my project (STEP and DIR signal for a a4988 stepper driver, or something similar).
There are some threads about the Raspberry Pi 4 and Mesa cards, but is it also possible to use the GPIO's of the RPI4 for STEP and DIR?
Regarding to the minimum system requirements it should work with the new Raspberry Pi 4, but is it a good idea, or is it recommendable to use a normal PC?
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26 Feb 2020 20:18 #158569
by BeagleBrainz
Replied by BeagleBrainz on topic RPI4 with GPIOs
There is some talk here:
www.mail-archive.com/emc-developers@list...ge.net/msg19605.html
That's about all I know. Regrading configuration and the rest hopefully some knows the score.
Tho I did see this
github.com/LinuxCNC/linuxcnc/blob/master...hal_pi_gpio_demo.hal
www.mail-archive.com/emc-developers@list...ge.net/msg19605.html
That's about all I know. Regrading configuration and the rest hopefully some knows the score.
Tho I did see this
github.com/LinuxCNC/linuxcnc/blob/master...hal_pi_gpio_demo.hal
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03 Mar 2020 23:38 #159122
by andypugh
Yes, though you might get disappointing step rates.
You can't step any faster than the base thread rate. Looking around the forum I see base-thread latency figures of about 50µs so that would be step rates of no more than 5kHz in practice. (as the Pi GPIO driver does not have the reset functionality of the Parport driver.
(Though it would not be so hard to add it, I don't think)
I suppose that could be enough, what do you expect to need?
Replied by andypugh on topic RPI4 with GPIOs
is it also possible to use the GPIO's of the RPI4 for STEP and DIR?
Yes, though you might get disappointing step rates.
You can't step any faster than the base thread rate. Looking around the forum I see base-thread latency figures of about 50µs so that would be step rates of no more than 5kHz in practice. (as the Pi GPIO driver does not have the reset functionality of the Parport driver.
(Though it would not be so hard to add it, I don't think)
I suppose that could be enough, what do you expect to need?
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