prusst 1.0.0

A convenient interface to the UIO kernel module for TI Programmable Real-time Units.
Documentation 
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//! Flash the BeagleBone USR1 LED 5 times at 2Hz.
//!
//! The PRU code notifies the host processor every time the LED is flashed by triggering Evtout0.
//! The 6-th event out is interpreted as a completion notification. 

extern crate prusst;

use prusst::{Pruss, IntcConfig, Evtout, Sysevt};

use std::fs::File;
use std::io::Write;

static LED_TRIGGER_PATH: &'static str = "/sys/class/leds/beaglebone:green:usr1/trigger";
static LED_DEFAULT_TRIGGER: &'static str = "mmc0";


fn echo(value: &str, path: &str) {
    let mut file = File::create(path).unwrap();
    file.write_all(value.as_bytes()).unwrap();
}


fn main() {
    // Get a view of the PRU subsystem.
    let mut pruss = match Pruss::new(&IntcConfig::new_populated()) {
        Ok(p) => p,
        Err(e) => match e {
            prusst::Error::AlreadyInstantiated
                => panic!("You can't instantiate more than one `Pruss` object at a time."),
            prusst::Error::PermissionDenied
                => panic!("You do not have permission to access the PRU subsystem: \
                           maybe you should run this program as root?"),
            prusst::Error::DeviceNotFound
                => panic!("The PRU subsystem could not be found: are you sure the `uio_pruss` \
                           module is loaded and supported by your kernel?"),
            prusst::Error::OtherDeviceError
                => panic!("An unidentified problem occured with the PRU subsystem: \
                           do you have a valid overlay loaded?")
        }
    };
    
    // Get a handle to an event out.
    let irq = pruss.intc.register_irq(Evtout::E0);

    // Open and load the PRU binary.
    let mut pru_binary = File::open("examples/barebone_blink_pru0.bin").unwrap();
    
    // Temporarily take control of the LED.
    echo("none", LED_TRIGGER_PATH);

    // Run the PRU binary.
    unsafe { pruss.pru0.load_code(&mut pru_binary).unwrap().run(); }
    
    // Let us know when the LED is turned on.
    for i in 1..6 {
        // Wait for the PRU to trigger the event out.
        irq.wait();
        println!("Blink {}", i);

        // Clear the triggering interrupt and re-enable the host irq.
        pruss.intc.clear_sysevt(Sysevt::S19);
        pruss.intc.enable_host(Evtout::E0);
    }

    // Wait for completion of the PRU code.
    irq.wait();
    pruss.intc.clear_sysevt(Sysevt::S19);
    println!("Goodbye!");
    
    // Restore default LED status.
    echo(LED_DEFAULT_TRIGGER, LED_TRIGGER_PATH);
}