dht20 0.1.0

platform agnostic driver for dht20 temperature and humidity sensor
Documentation 
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#![no_std]

use core::fmt;

use embedded_hal::blocking::delay::DelayMs;
use embedded_hal::blocking::i2c::{Read, Write, WriteRead};
use log::info;

pub struct Dht20<I2C, D> {
    i2c: I2C,
    address: u8,
    delay: D,
}

#[derive(Debug, Clone)]
pub struct Reading {
    pub temp: f32,
    pub hum: f32,
}

#[derive(Debug)]
pub enum Error<E: fmt::Debug> {
    I2cError(E),
    ReadToFast,
}

impl<I2C, E, D> Dht20<I2C, D>
where
    I2C: Read<Error = E> + Write<Error = E> + WriteRead<Error = E>,
    E: fmt::Debug,
    D: DelayMs<u16>,
{
    pub fn new(i2c: I2C, address: u8, delay: D) -> Self {
        Self {
            i2c,
            address,
            delay,
        }
    }

    pub fn read(&mut self) -> Result<Reading, E> {
        self.reset()?;
        // request reading
        self.write_data(&[0xAC, 0x33, 0])?;
        self.delay.delay_ms(80);
        // read data
        let data = self.read_data()?;
        // convert values
        let mut raw = (data[1] as u32) << 8;
        raw += data[2] as u32;
        raw <<= 4;
        raw += (data[3] >> 4) as u32;
        let hum = raw as f32 * 9.5367431640625e-5; // ==> / 1048576.0 * 100%;

        let mut raw = (data[3] & 0x0F) as u32;
        raw <<= 8;
        raw += data[4] as u32;
        raw <<= 8;
        raw += data[5] as u32;
        let temp = raw as f32 * 1.9073486328125e-4 - 50.0; //  ==> / 1048576.0 * 200 - 50;
        Ok(Reading { temp, hum })
    }

    fn reset(&mut self) -> Result<(), E> {
        let status = self.read_status()?;
        if status & 0x18 != 0x18 {
            info!("resetting");
            self.write_data(&[0x1B, 0, 0])?;
            self.write_data(&[0x1C, 0, 0])?;
            self.write_data(&[0x1E, 0, 0])?;
        }
        Ok(())
    }

    fn read_data(&mut self) -> Result<[u8; 8], E> {
        let mut buffer = [0; 8];
        self.i2c.read(self.address, &mut buffer)?;
        Ok(buffer)
    }

    fn read_status(&mut self) -> Result<u8, E> {
        let mut buffer = [0; 1];
        self.i2c.read(self.address, &mut buffer)?;
        Ok(buffer[0])
    }

    fn write_data(&mut self, data: &[u8]) -> Result<(), E> {
        self.i2c.write(self.address, data)
    }
}