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Better docs and rename transact()

This commit is contained in:
Leonora Tindall 2019-12-29 11:58:05 -08:00
parent f4bd7b67e4
commit 8e52f10ffc
Signed by: nora
GPG Key ID: 7A8B52EC67E09AAF
2 changed files with 152 additions and 24 deletions
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1
CHANGELOG.md
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@ -11,6 +11,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
- GNU GPL v3 license
- Cargo metadata
- Basic functionality
### Changed

175
src/lib.rs
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@ -1,3 +1,14 @@
//! ## A Rusty interface for the RN2903 serial protocol
//!
//! The RN2903 is a LoRa and FSK transciever for the 915MHz ISM band, commonly used in USB
//! devices like the LoStik.
//!
//! This crate provides a safe, idiomatic interface using cross-platform native serial
//! functionality via `serialport`. This supports, for instance, a LoStik connected to a USB
//! TTY or virtual COM port, or a RN2903 connected via a TTL serial interface.
//!
//! See the [`Rn2903` struct](struct.Rn2903.html) for the bulk of the crate's functionality.
// One of the critical aspects of this library is error handling. Because it is intended
// to communicate with an external device, any operation could discover a disconnection
// from the RN2903 serial link, so everything which does such communication will return
@ -7,6 +18,7 @@ extern crate quick_error;
use std::io;
quick_error! {
/// The primary error type used for fallible operations on the RN2903.
#[derive(Debug)]
pub enum Error {
/// The connection to the RN2903 was impossible for some reason. Perhaps an
@ -36,7 +48,7 @@ quick_error! {
}
/// Universal `Result` wrapper for the RN2903 interface.
type Result<T> = std::result::Result<T, Error>;
pub type Result<T> = std::result::Result<T, Error>;
// It's first necessary to actually connect to the module. To this end, the library
// exports all the configuration information needed to configure a serial port to
@ -49,12 +61,27 @@ use std::ffi::OsStr;
use std::io::prelude::*;
use std::thread;
/// Returns a `serialport::SerialPortSettings` corresponding to the default settings of
/// an RNB2903. Use this to configure your serial port.
/// Returns the `SerialPortSettings` corresponding to the default settings of
/// an RNB2903.
///
/// Information obtained from Microchip document 40001811 revision B. Timeout is by
/// default set to a very long time; this is sometimes modified on the `SerialPort` itself
/// during certain operations.
///
/// # Examples
///
/// Opening a serial port with slightly modified settings. In this case, the baud rate
/// has been reduced.
///
/// ```no_run
/// let settings = serialport::SerialPortSettings {
/// baud_rate: 9600,
/// ..rn2903::serial_config()
/// };
///
/// serialport::open_with_settings("/dev/ttyUSB0", &settings)
/// .expect("Could not open serial port. Error");
/// ```
pub fn serial_config() -> SerialPortSettings {
SerialPortSettings {
baud_rate: 57600,
@ -62,7 +89,7 @@ pub fn serial_config() -> SerialPortSettings {
flow_control: FlowControl::None,
parity: Parity::None,
stop_bits: StopBits::One,
timeout: Duration::new(1, 0),
timeout: Duration::new(65535, 0),
}
}
@ -71,30 +98,70 @@ pub fn serial_config() -> SerialPortSettings {
// wrapper struct's `::new()` function checks the output of the `sys get ver` command,
// which is well-specified.
// In order to turn the raw bytes into a String for display, this helper function comes
// in handy.
fn bytes_to_string(bytes: &[u8]) -> String {
/// Turn the raw bytes into a String for display.
pub fn bytes_to_string(bytes: &[u8]) -> String {
(&*String::from_utf8_lossy(bytes)).into()
}
/// A handle to a serial link connected to a RN2903 module.
///
/// This library guarantees safety regardless of the state of the RN2903.
/// This library guarantees safety regardless of the state of the RN2903. Refer to the
/// documentation for sections and individual associated functions for specifics.
///
/// # Examples
///
/// Basic functionality can be obtained just by using `::new_at()` and `::transact()`.
/// For instance, blinking the LoStik's LED:
///
/// ```no_run
/// # use rn2903::Rn2903;
/// # use std::time::Duration;
/// # use std::thread;
/// let mut txvr = Rn2903::new_at("/dev/ttyUSB0")
/// .expect("Could not open device. Error");
/// loop {
/// txvr.transact(b"radio set pindig GPIO10 0").unwrap();
/// thread::sleep(Duration::from_millis(1000));
/// txvr.transact(b"radio set pindig GPIO10 1").unwrap();
/// thread::sleep(Duration::from_millis(1000));
/// }
/// ```
pub struct Rn2903 {
port: Box<dyn SerialPort>,
}
/// # Meta (type) Functions
///
/// These functions deal with the type `Rn2903`, providing ways to create and manipulate
/// the structure itself. Aside from performing validation of the device on the other side
/// of the serial link, these functions do not communicate with the module.
///
/// ## Creating an `Rn2903`
/// There are several ways to create a `Rn2903` wrapper for an RN2903 serial connection.
/// `::new_at()` is the recommended method, but `::new()` can be useful if the platform
/// does not support named serial ports, or some extra configuration is needed.
impl Rn2903 {
/// Open a new connection to a module at the given path or port name, with the
/// default settings.
/// Opens a new connection to a module at the given path or port name, with the
/// default (and usually correct) settings from
/// [`serial_config`](fn.serial_config.html).
///
/// # Example
///
/// Connecting to a module accessible over the USB0 TTY.
/// ```no_run
/// # use rn2903::Rn2903;
/// let txvr = Rn2903::new_at("/dev/ttyUSB0")
/// .expect("Could not open device. Error");
/// ```
pub fn new_at<S: AsRef<OsStr>>(port_name: S) -> Result<Self> {
let sp = serialport::open_with_settings(&port_name, &serial_config())?;
Self::new(sp)
}
/// Open a new connection to a module over the given serial connection.
/// Open a new connection to a module over the connection described by the given
/// `SerialPort` trait object.
pub fn new(port: Box<dyn SerialPort>) -> Result<Self> {
let mut new = Self { port };
let mut new = Self::new_unchecked(port);
let version = new.system_version()?;
if &version[0..6] != "RN2903" {
Err(Error::WrongDevice(version))
@ -103,30 +170,78 @@ impl Rn2903 {
}
}
/// Query the module for its firmware version information.
/// Open a new connection to a module over the connection described by the given
/// `SerialPort` trait object without performing a `sys get ver` check.
///
/// Returns a `String` like `RN2903 1.0.3 Aug 8 2017 15:11:09`
pub fn system_version(&mut self) -> Result<String> {
let bytes = self.transact_command(b"sys get ver\x0D\x0A")?;
Ok(bytes_to_string(&bytes))
/// The results of operations on a `Rn2903` struct that does _not_ represent an
/// actual connection to an RN2903 module are completely unpredictable, and may
/// result in lots of badness (though not memory unsafety).
pub fn new_unchecked(port: Box<dyn SerialPort>) -> Self {
Self { port }
}
/// Acquires temporary direct access to the captured `SerialPort` trait object.
///
/// Use this access to, for example, reconfigure the connection on the fly,
/// or set flags that will be used by devices this crate is unaware of.
///
/// # Example
///
/// Raising and then lowering the RTS signal, for example to signal a bus observer
/// to switch on.
/// ```no_run
/// # use rn2903::Rn2903;
/// # use std::thread;
/// # use std::time::Duration;
/// # let mut txvr = Rn2903::new_at("/dev/ttyUSB0")
/// # .expect("Could not open device. Error");
/// txvr.port().write_request_to_send(true)
/// .expect("Could not set RTS. Error");
/// thread::sleep(Duration::from_millis(25));
/// txvr.port().write_request_to_send(false)
/// .expect("Could not set RTS. Error");
/// ```
pub fn port(&mut self) -> &mut dyn SerialPort {
&mut *self.port
}
}
/// Write the specified command to the module and get a single line of response.
/// # Low-level Communications
impl Rn2903 {
/// Writes the specified command to the module and returns a single line in response.
///
/// This function adds the CRLF to the given command and returns the response without
/// the CRLF.
pub fn transact_command(&mut self, command: &[u8]) -> Result<Vec<u8>> {
use std::io::IoSlice;
self.port.write_vectored(&[IoSlice::new(command), IoSlice::new(b"\x0D\x0A")])?;
self.port.flush()?;
///
/// This is the preferred low-level communication method, since the RN2903 is supposed
/// to respond with a single line to every command.
pub fn transact(&mut self, command: &[u8]) -> Result<Vec<u8>> {
self.send_line(command)?;
self.read_line()
}
/// Read bytes from the device until a CRLF is encountered, then returns the bytes
/// Writes the specified command to the module, adding a CRLF and flushing the buffer.
///
/// Using [`::transact()`](#method.transact) is preferred.
pub fn send_line(&mut self, line: &[u8]) -> Result<()> {
use std::io::IoSlice;
let bytes: Vec<u8> = line.iter().chain(b"\x0D\x0A".iter()).cloned().collect();
let mut cursor = 0;
while cursor < bytes.len() {
cursor += self.port.write(&bytes[cursor..])?;
}
self.port.flush()?;
thread::sleep(Duration::from_millis(500));
Ok(())
}
/// Reads bytes from the device until a CRLF is encountered, then returns the bytes
/// read, not including the CRLF.
///
/// Using [`::transact()`](#method.transact) is preferred.
// This operation waits 12ms between each 32-byte read because the LoStick has
// the hiccups.
fn read_line(&mut self) -> Result<Vec<u8>> {
pub fn read_line(&mut self) -> Result<Vec<u8>> {
let mut vec = Vec::with_capacity(32);
loop {
let mut buf = [0; 32];
@ -160,4 +275,16 @@ impl Rn2903 {
Ok(vec)
}
}
/// # System API Functions
impl Rn2903 {
/// Queries the module for its firmware version information.
///
/// Returns a `String` like `RN2903 1.0.3 Aug 8 2017 15:11:09`
pub fn system_version(&mut self) -> Result<String> {
let bytes = self.transact(b"sys get ver")?;
Ok(bytes_to_string(&bytes))
}
}