sen0177

sen0177 is a Rust library/crate that reads air quality data from the SEN0177 air quality sensor.

Prerequisites

• You've connected the sensor to a UART or I2C bus on your device, and your device has a crate implementing the applicable [embedded_hal] traits.
• For a UART-based sensor, you've configured the UART for 9600 baud, 8 data bits, no parity, 1 stop bit, and no flow control.

Setup

Include the following in your Cargo.toml file:

toml [dependencies] sen0177 = "0.4"

If you are in a no_std environment, you may depend on this crate like so:

toml [dependencies] sen0177 = { version = "0.4", default-features = false }

Usage

This example shows how to use the sensor when connected to a Linux- based serial device.

Note that this example currently does not work becuase this crate is tracking the current embedded-hal 1.0.0 alpha, but linux-embedded-hal is a little behind at the time of writing. If you want to use my patched version, add the following to your Cargo.toml:

toml [patch.crates-io] linux-embedded-hal = { git = "https://github.com/kelnos/linux-embedded-hal.git", branch = "embedded-hal-1.0.0-alpha.8" }

```rust,norun,ignore use linuxembedded_hal::Serial; use sen0177::{serial::Sen0177, Reading}; use serial::{core::prelude::*, BaudRate, CharSize, FlowControl, Parity, StopBits}; use std::{io, path::Path, time::Duration};

const SERIALPORT: &str = "/dev/ttyS0"; const BAUDRATE: BaudRate = BaudRate::Baud9600; const CHARSIZE: CharSize = CharSize::Bits8; const PARITY: Parity = Parity::ParityNone; const STOPBITS: StopBits = StopBits::Stop1; const FLOW_CONTROL: FlowControl = FlowControl::FlowNone;

pub fn main() -> anyhow::Result<()> { let mut serial = Serial::open(&Path::new(SERIALPORT))?; serial.0.settimeout(Duration::frommillis(1500))?; serial.0.reconfigure(&|settings| { settings.setcharsize(CHARSIZE); settings.setparity(PARITY); settings.setstopbits(STOPBITS); settings.setflowcontrol(FLOWCONTROL); settings.setbaudrate(BAUDRATE) })?; let mut sensor = Sen0177::new(serial);

loop {
    match sensor.read() {
        Ok(reading) => {
            println!("PM1: {}µg/m³, PM2.5: {}µg/m³, PM10: {}µg/m³",
                     reading.pm1(), reading.pm2_5(), reading.pm10());
        },
        Err(err) => eprintln!("Error: {:?}", err),
    }
}

} ```

Note that the serial device occasionally returns bad data. If you receive [SensorError::BadMagic] or [SensorError::ChecksumMismatch] from the [AirQualitySensor::read] call, a second try will usually succeed.

Gotchas

Raspberry Pi

If you're using this with a Raspberry Pi, note that by default the primary UART is set up as a Linux serial console. You will need to disable that (by editing /boot/cmdline.txt) before this will work. Instead of using a specifiy TTY device node, you should use /dev/serial0, which is a symlink to the proper device.

Alternatively, you can use the second UART, but you'll need to load an overlay to assign it to GPIO pins. See UART configuration and the UART-related overlays for more information.