Difference between revisions of "Raspberry Pi CNC v2.51"
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The buttons : RESET,ABORT,HOLD,RESUME work with normally open buttons and gets activated when grounded. All buttons are pulled high. | The buttons : RESET,ABORT,HOLD,RESUME work with normally open buttons and gets activated when grounded. All buttons are pulled high. | ||
| − | ===Coolant, Spindle Direction, Spindle Speed | + | ===Coolant, Spindle Direction, Spindle Speed=== |
==Software== | ==Software== | ||
Revision as of 16:18, 10 May 2016
Contents
Overview
The RPI CNC Board combines a real-time CNC controller(Micro-controller running GRBL) with a powerful credit card size computer(Raspberry Pi).
By combining the two systems we have created an eco-system where the Raspberry Pi provides benefits like: Processing power, connectivity(IOT) and a well supported community.
The board plugs directly into the Raspberry Pi General Purpose Input/Output pins, with the micro-controller and Raspberry Pi communicating via serial. (/dev/ttyAMA0)
Availability, Update Notifications and Forums
Installation and configuration
IMPORTANT: None of the components should be powered while installing or configuring.
Quick Start Guide
WARNING: Do not power up the board with stepper drivers installed if they are not connected to stepper motors. The stepper drivers are current limiting and will overheat if they are not connected.
Raspberry Pi CNC - Quick Start Guide
Wiring Diagram
... Diagram Will Be Updated To The 4 Stepper Setup Soon ...
Micro Stepping Jumpers
In the tables below High indicates that a Jumper is inserted and Low indicates that no jumper is inserted.
| Jumper 1 | Jumper 2 | Jumper 3 | Microstep Resolution |
| Low | Low | Low | Full step |
| High | Low | Low | 1/2 step |
| Low | High | Low | 1/4 step |
| High | High | Low | 1/8 step |
| High | High | High | 1/16 step |
| Jumper 1 | Jumper 2 | Jumper 3 | Microstep Resolution |
| Low | Low | Low | Full step |
| High | Low | Low | 1/2 step |
| Low | High | Low | 1/4 step |
| High | High | Low | 1/8 step |
| Low | Low | High | 1/16 step |
| High | Low | High | 1/32 step |
| Low | High | High | 1/32 step |
| High | High | High | 1/32 step |
End Stops
End Stops use normally-open push-button type switches. The End-stop socket shares a common ground that connects to each axis end-stop. The pins are pulled high by the micro controller's internal pull-ups and will activate the end-stop when the pin is connected to ground.
GRBL v0.9 setting $21 needs to be set to 1 to activate hard-limits. Setting $22 also activated the Homing functionality.
V2.51 Introduces End-stop and Probe line filters to prevent noise on the lines.
Clone Drive (Introduced with V2.51)
The 4th Stepper Driver Socket can be configured to clone any of the other Axes. Configuration is done with the two rows of jumper headers situated under the Nano board.
4th Socket Cloning X Axis
4th Socket Cloning Y Axis
4th Socket Cloning Z Axis
4th Socket Disconnected
In the images above the green sections indicates a jumper positions to configure the 4th Stepper Motor Socket.
External Drivers
Below are images of the pins(in red) needed to connect to an external stepper driver for each axis. External Drivers usually run at 3.3-5V logic with the Raspberry Pi CNC board using 5V. (Check the external driver details before connecting.)
Needed pins are as follow:
- Stepper Pin
- Direction Pin
- Enable Pin
- Ground Pin
Special attention needs to be taken with the Enable pin. Pololu Drivers activate when the enable pin goes low/grounded. If the external drivers you are using needs active high you will not be able to use the enable pin but can instead just connect the external drivers enable pin to 5V to enable it.
External Drivers and Control Button pins
X-Axis pins
Y-Axis pins
Z-Axis pins
Cloned-Axis pins
Button Controls
The buttons : RESET,ABORT,HOLD,RESUME work with normally open buttons and gets activated when grounded. All buttons are pulled high.
Coolant, Spindle Direction, Spindle Speed
Software
In order for the GRBL to communicate with the Raspberry Pi, the hardware serial port on the Raspberry Pi needs to be enabled and working. HobbyTronics has a good tutorial on how to set it up and test it. Raspberry Pi Serial Port setup
Firmware (GRBL + Micro-Controller)
GRBL is the magic that does the actual control of the CNC machines.
For more details : GRBL
The Raspberry CNC board comes pre-loaded with GRBL but can be updated as follows : Flashing Grbl to an Arduino
Hardware
Version 2.51
- Extra Stepper Drivers Socket that can clone one of the other Axes.
- End-stop + Probe line noise filters. Allows end stops to work with normal un-shielded cable.
- Breakout pins allowing external Stepper drivers to be hooked up.
Version 2.11
- Initial Version
- 3-Axis (XYZ)
- End Stop for each Axis (XYZ)
- Variable Speed Spindle / Laser Intensity control (PWM Spindle pin and Direction pin)
- Coolant control pin. (Extra output pin)
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