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A safe, high-level interface to LinuxCNC's HAL (Hardware Abstraction Layer) module.
For lower level, unsafe use, see the
linuxcnc-hal-sys
crate.
bindgen
must be set up correctly. Follow the
requirements section of its docs.
To run and debug any HAL components, the LinuxCNC simulator can be set up. There's a guide here for Linux Mint (and other Debian derivatives).
This crate depends on the linuxcnc-hal-sys
crate which requires the LINUXCNC_SRC
environment
variable to be set to correctly generate the C bindings. The value must be the absolute path to
the root of the LinuxCNC source code.
The version of the LinuxCNC sources must match the LinuxCNC version used in the machine control.
# Clone LinuxCNC source code into linuxcnc/
git clone https://github.com/LinuxCNC/linuxcnc.git
# Check out a specific version tag. This may also be a commit, but must match the version in use by the machine control.
cd linuxcnc && git checkout v2.8.0 && cd ..
# Create your component lib
cargo new --lib my_comp
cd my_comp
# Add LinuxCNC HAL bindings as a Cargo dependency with cargo-edit
cargo add linuxcnc-hal
LINUXCNC_SRC=/path/to/linuxcnc/source/code cargo build
If LinuxCNC is configured to run in place, liblinuxcnchal.so.0
may not be found on startup. To
fix, try setting the library path with e.g. export LD_LIBRARY_PATH=~/Repositories/linuxcnc/lib
This example creates a component called "pins"
with a single input ("input-1"
) and output
pin ("output-1"
). It enters an infinite loop which updates the value of output-1
every
second. LinuxCNC convention dictates that component and pin names should be dash-cased
.
This example can be loaded into LinuxCNC with a .hal
file that looks similar to this:
loadusr -W /path/to/your/component/target/debug/comp_bin_name
net input-1 spindle.0.speed-out pins.input-1
net output-1 pins.output-1
Pins and other resources are registered using the Resources
trait. This example creates a
Pins
struct which holds the two pins. HalComponent::new
handles component creation,
resources (pin, signal, etc) initialisation and UNIX signal handler registration.
use linuxcnc_hal::{
error::PinRegisterError,
hal_pin::{InputPin, OutputPin},
prelude::*,
HalComponent, RegisterResources, Resources,
};
use std::{
error::Error,
thread,
time::{Duration, Instant},
};
struct Pins {
input_1: InputPin<f64>,
output_1: OutputPin<f64>,
}
impl Resources for Pins {
type RegisterError = PinRegisterError;
fn register_resources(comp: &RegisterResources) -> Result<Self, Self::RegisterError> {
Ok(Pins {
input_1: comp.register_pin::<InputPin<f64>>("input-1")?,
output_1: comp.register_pin::<OutputPin<f64>>("output-1")?,
})
}
}
fn main() -> Result<(), Box<dyn Error>> {
rtapi_logger::init();
// Create a new HAL component called `rust-comp`
let comp: HalComponent<Pins> = HalComponent::new("rust-comp")?;
// Get a reference to the `Pins` struct
let pins = comp.resources();
let start = Instant::now();
// Main control loop
while !comp.should_exit() {
let time = start.elapsed().as_secs() as i32;
// Set output pin to elapsed seconds since component started
pins.output_1.set_value(time.into())?;
// Print the current value of the input pin
println!("Input: {:?}", pins.input_1.value());
// Sleep for 1000ms. This should be a lower time if the component needs to update more
// frequently.
thread::sleep(Duration::from_millis(1000));
}
// The custom implementation of `Drop` for `HalComponent` ensures that `hal_exit()` is called
// at this point. Registered signal handlers are also deregistered.
Ok(())
}
Licensed under either of
- Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
- MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)
at your option.
Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.