156 lines
7.3 KiB
Markdown
156 lines
7.3 KiB
Markdown
This document describes the process of running Klipper on a RPi
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and use the same RPi as secondary mcu.
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Why use RPi as a secondary MCU?
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===============================
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Often the MCUs dedicated to controlling 3D printers have a limited and
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pre-configured number of exposed pins to manage the main printing
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functions (thermal resistors, extruders, steppers ...).
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Using the RPi where Klipper is installed as a secondary MCU gives the
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possibility to directly use the GPIOs and the buses (i2c, spi) of the RPi
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inside klipper without using Octoprint plugins (if used) or external
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programs giving the ability to control everything within the print GCODE.
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**Warning**: If your platform is a _Beaglebone_ and you have correctly followed the installation steps, the linux mcu is already installed and configured for your system.
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Install the rc script
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=====================
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If you want to use the host as a secondary MCU the klipper_mcu process must run before the klippy process.
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After installing Klipper, install the script. run:
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```
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cd ~/klipper/
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sudo cp "./scripts/klipper-mcu-start.sh" /etc/init.d/klipper_mcu
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sudo update-rc.d klipper_mcu defaults
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```
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Building the micro-controller code
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==================================
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To compile the Klipper micro-controller code, start by configuring it
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for the "Linux process":
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```
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cd ~/klipper/
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make menuconfig
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```
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To build and install the new micro-controller code, run:
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```
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sudo service klipper stop
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make flash
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sudo service klipper start
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```
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If klippy.log reports a "Permission denied" error when attempting to connect
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to `/tmp/klipper_host_mcu` then you need to add your user to the tty group.
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The following command will add the "pi" user to the tty group:
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```
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sudo usermod -a -G tty pi
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```
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Remaining configuration
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=======================
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Complete the installation by configuring Klipper secondary MCU
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following the instructions in
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[RaspberryPi sample config](../config/sample-raspberry-pi.cfg) and
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[Multi MCU sample config](../config/sample-multi-mcu.cfg).
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Optional: Identify the correct gpiochip
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=======================================
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On Rasperry and on many clones the pins exposed on the GPIO belong to the first gpiochip. They can therefore be used on klipper simply by referring them with the name `gpio0..n`.
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However, there are cases in which the exposed pins belong to gpiochips other than the first. For example in the case of some OrangePi models or if a Port Expander is used. In these cases it is useful to use the commands to access the _Linux GPIO character device_ to verify the configuration.
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To install the _Linux GPIO character device - binary_ on a debian based distro like octopi run:
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```
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sudo apt-get install gpiod
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```
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To check available gpiochip run:
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```
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gpiodetect
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```
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To check the pin number and the pin availability tun:
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```
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gpioinfo
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```
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The chosen pin can thus be used within the configuration as `gpiochip<n>/gpio<o>` where **n** is the chip number as seen by the `gpiodetect` command and **o** is the line number seen by the` gpioinfo` command.
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***Warning:*** only gpio marked as `unused` can be used. It is not possible for a _line_ to be used by multiple processes simultaneously.
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For example on a RPi 3B+ where klipper use the GPIO20 for a switch:
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```
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$ gpiodetect
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gpiochip0 [pinctrl-bcm2835] (54 lines)
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gpiochip1 [raspberrypi-exp-gpio] (8 lines)
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$ gpioinfo
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gpiochip0 - 54 lines:
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line 0: unnamed unused input active-high
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line 1: unnamed unused input active-high
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line 2: unnamed unused input active-high
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line 3: unnamed unused input active-high
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line 4: unnamed unused input active-high
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line 5: unnamed unused input active-high
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line 6: unnamed unused input active-high
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line 7: unnamed unused input active-high
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line 8: unnamed unused input active-high
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line 9: unnamed unused input active-high
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line 10: unnamed unused input active-high
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line 11: unnamed unused input active-high
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line 12: unnamed unused input active-high
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line 13: unnamed unused input active-high
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line 14: unnamed unused input active-high
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line 15: unnamed unused input active-high
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line 16: unnamed unused input active-high
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line 17: unnamed unused input active-high
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line 18: unnamed unused input active-high
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line 19: unnamed unused input active-high
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line 20: unnamed "klipper" output active-high [used]
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line 21: unnamed unused input active-high
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line 22: unnamed unused input active-high
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line 23: unnamed unused input active-high
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line 24: unnamed unused input active-high
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line 25: unnamed unused input active-high
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line 26: unnamed unused input active-high
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line 27: unnamed unused input active-high
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line 28: unnamed unused input active-high
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line 29: unnamed "led0" output active-high [used]
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line 30: unnamed unused input active-high
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line 31: unnamed unused input active-high
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line 32: unnamed unused input active-high
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line 33: unnamed unused input active-high
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line 34: unnamed unused input active-high
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line 35: unnamed unused input active-high
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line 36: unnamed unused input active-high
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line 37: unnamed unused input active-high
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line 38: unnamed unused input active-high
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line 39: unnamed unused input active-high
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line 40: unnamed unused input active-high
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line 41: unnamed unused input active-high
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line 42: unnamed unused input active-high
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line 43: unnamed unused input active-high
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line 44: unnamed unused input active-high
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line 45: unnamed unused input active-high
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line 46: unnamed unused input active-high
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line 47: unnamed unused input active-high
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line 48: unnamed unused input active-high
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line 49: unnamed unused input active-high
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line 50: unnamed unused input active-high
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line 51: unnamed unused input active-high
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line 52: unnamed unused input active-high
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line 53: unnamed unused input active-high
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gpiochip1 - 8 lines:
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line 0: unnamed unused input active-high
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line 1: unnamed unused input active-high
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line 2: unnamed "led1" output active-low [used]
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line 3: unnamed unused input active-high
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line 4: unnamed unused input active-high
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line 5: unnamed unused input active-high
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line 6: unnamed unused input active-high
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line 7: unnamed unused input active-high
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```
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