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//! Platform agnostic Rust driver for Sensirion SVM40 device with //! gas, temperature and humidity sensors based on //! the [`embedded-hal`](https://github.com/japaric/embedded-hal) traits. //! //! ## Sensirion SVM40 //! //! Sensirion SGPC3 is a low-power accurate gas sensor for air quality application. //! The sensor has different sampling rates to optimize power-consumption per application //! bases as well as ability save and set the baseline for faster start-up accuracy. //! The sensor uses I²C interface and measures TVOC (*Total Volatile Organic Compounds*) //! //! Evaluation board: https://www.sensirion.com/cn/environmental-sensors/evaluation-kit-sek-svm40/ //! //! ## Usage //! //! ### Instantiating //! //! Import this crate and an `embedded_hal` implementation, then instantiate //! the device: //! //! ```no_run //! use linux_embedded_hal as hal; //! //! use hal::{Delay, I2cdev}; //! use svm40::Svm40; //! //! fn main() { //! let dev = I2cdev::new("/dev/i2c-1").unwrap(); //! let mut sgp = Svm40::new(dev, 0x6a, Delay); //! } //! ``` //! ### Doing Measurements //! //! The device is doing measurements independently of the driver and calls to the device //! will just fetch the latest information making the usage easy. //! //! ```no_run //! use linux_embedded_hal as hal; //! use hal::{Delay, I2cdev}; //! //! use std::time::Duration; //! use std::thread; //! //! use svm40::Svm40; //! //! fn main() { //! let dev = I2cdev::new("/dev/i2c-1").unwrap(); //! //! let mut sensor = Svm40::new(dev, 0x6A, Delay); //! //! let version = sensor.version().unwrap(); //! //! println!("Version information {:?}", version); //! //! let mut serial = [0; 26]; //! //! sensor.serial(&mut serial).unwrap(); //! //! println!("Serial {:?}", serial); //! //! sensor.start_measurement().unwrap(); //! //! thread::sleep(Duration::new(2_u64, 0)); //! //! for _ in 1..20 { //! let signals = sensor.get_measurements().unwrap(); //! println!("Measurements: {:?}", signals); //! thread::sleep(Duration::new(1_u64, 0)); //! //! let signals = sensor.get_raw_measurements().unwrap(); //! println!("Measurements: {:?}", signals); //! thread::sleep(Duration::new(1_u64, 0)); //! } //! sensor.stop_measurement().unwrap(); //! } //! ``` #![cfg_attr(not(test), no_std)] use embedded_hal as hal; use hal::blocking::delay::DelayMs; use hal::blocking::i2c::{Read, Write, WriteRead}; use sensirion_i2c::{crc8, i2c}; /// Standard signal measurement #[derive(Debug, Copy, Clone, PartialEq)] pub struct Signals { /// VOC algorithm output with a scaling value of 10. pub voc_index: u16, /// Compensated ambient humidity in %RH with a scaling factor of 100. pub relative_humidity: u16, /// Compensated ambient temperature in degree celsius with a scaling factor of 200. pub temperature: u16, } impl Signals { fn parse(data: &[u8]) -> Self { Signals { voc_index: u16::from_be_bytes([data[0], data[1]]), relative_humidity: u16::from_be_bytes([data[6], data[7]]), temperature: u16::from_be_bytes([data[3], data[4]]), } } } /// Raw signal measurement. Raw signals include the standard signals. #[derive(Debug, Copy, Clone)] pub struct RawSignals { pub standard: Signals, /// Raw VOC output ticks as read from the SGP sensor. pub voc_ticks_raw: u16, /// Uncompensated raw humidity in %RH as read from the SHT40 with a scaling factor of 100. pub uncompensated_relative_humidity: u16, /// Uncompensated raw temperature in degrees celsius as read from the SHT40 with a scaling of 200. pub uncompensated_temperature: u16, } impl RawSignals { fn parse(data: &[u8]) -> Self { let standard = Signals::parse(&data[0..9]); RawSignals { standard, voc_ticks_raw: u16::from_be_bytes([data[9], data[10]]), uncompensated_relative_humidity: u16::from_be_bytes([data[15], data[16]]), uncompensated_temperature: u16::from_be_bytes([data[12], data[13]]), } } } /// Svm40 errors #[derive(Debug)] pub enum Error<E> { /// I²C bus error I2c(E), /// CRC checksum validation failed Crc, } impl<E, I2cWrite, I2cRead> From<i2c::Error<I2cWrite, I2cRead>> for Error<E> where I2cWrite: Write<Error = E>, I2cRead: Read<Error = E>, { fn from(err: i2c::Error<I2cWrite, I2cRead>) -> Self { match err { i2c::Error::Crc => Error::Crc, i2c::Error::I2cWrite(e) => Error::I2c(e), i2c::Error::I2cRead(e) => Error::I2c(e), } } } #[derive(Debug, Copy, Clone)] enum Command { /// Starts the measurement StartMeasurement, /// Gets signals GetSignals, /// Gets raw signals GetRawSignals, /// Stops the measurement StopMeasurement, /// Gets temperature offset GetTemperatureOffset, /// Sets the temperature offset SetTemperatureOffset, /// Gets VOC parameters GetVocParameters, /// Sets VOC parameters SetVocParameters, /// Stores input parameters StoreInputParameters, /// Gets VOC states GetVocStates, /// Sets VOC states SetVocStates, /// Gets the sensor version information GetVersion, /// Resets the device Reset, // TODO: Add get serial - supported in the code but not in spec. Serial } impl Command { /// Command and the requested delay in ms fn as_tuple(self) -> (u16, u32) { match self { Command::StartMeasurement => (0x0010, 1), Command::GetSignals => (0x03a6, 1), Command::GetRawSignals => (0x03b0, 1), Command::StopMeasurement => (0x0104, 1), Command::GetTemperatureOffset => (0x6014, 1), Command::SetTemperatureOffset => (0x6014, 1), Command::GetVocParameters => (0x6083, 1), Command::SetVocParameters => (0x6083, 1), Command::StoreInputParameters => (0x6002, 1), Command::GetVocStates => (0x6181, 1), Command::SetVocStates => (0x6181, 1), Command::GetVersion => (0xd100, 1), Command::Reset => (0xd304, 1), Command::Serial => (0xd033, 1) } } } /// Version information structure #[derive(Debug)] pub struct Version { /// Major firmware version pub sw_major_ver: u8, /// Minor firmware version pub sw_minor_ver: u8, /// Shows if the device is on debug state pub debug_state: bool, /// Major hardware version pub hw_major_ver: u8, /// Minor hardware version pub hw_minor_ver: u8, /// Major protocol version pub protocol_major_ver: u8, /// Minor protocol version pub protocol_minor_ver: u8, } /// Svm40 main driver to manipulate the sensor #[derive(Debug, Default)] pub struct Svm40<I2C, D> { i2c: I2C, address: u8, delay: D, } impl<I2C, D, E> Svm40<I2C, D> where I2C: Read<Error = E> + Write<Error = E> + WriteRead<Error = E>, D: DelayMs<u32>, { pub fn new(i2c: I2C, address: u8, delay: D) -> Self { Svm40 { i2c, address, delay, } } /// Command for reading values from the sensor fn delayed_read_cmd(&mut self, cmd: Command, data: &mut [u8]) -> Result<(), Error<E>> { self.write_command(cmd)?; i2c::read_words_with_crc(&mut self.i2c, self.address, data)?; Ok(()) } /// Writes commands with arguments fn write_command_with_args(&mut self, cmd: Command, data: &[u8]) -> Result<(), Error<E>> { const MAX_TX_BUFFER: usize = 14; //cmd (2 bytes) + max args (12 bytes) let mut transfer_buffer = [0; MAX_TX_BUFFER]; let size = data.len(); // 2 for command, size of transferred bytes and CRC per each two bytes. assert!(size < 2 + size + size / 2); let (command, delay) = cmd.as_tuple(); transfer_buffer[0..2].copy_from_slice(&command.to_be_bytes()); let mut i = 2; for chunk in data.chunks(2) { let end = i+2; transfer_buffer[i..end].copy_from_slice(chunk); transfer_buffer[end] = crc8::calculate(chunk); i += 3; } self.i2c .write(self.address, &transfer_buffer[0..i]) .map_err(Error::I2c)?; self.delay.delay_ms(delay); Ok(()) } /// Writes commands without additional arguments. fn write_command(&mut self, cmd: Command) -> Result<(), Error<E>> { let (command, delay) = cmd.as_tuple(); i2c::write_command(&mut self.i2c, self.address, command).map_err(Error::I2c)?; self.delay.delay_ms(delay); Ok(()) } fn command_ret_u64(&mut self, cmd: Command) -> Result<u64, Error<E>> { let mut buffer = [0; 12]; // If somebody knows how to turn the array above into reference of [0; 8] so that I can reuse // the same memory for putting u64 array together, please, let me know let mut data = [0; 8]; self.delayed_read_cmd(cmd, &mut buffer)?; let mut i = 0; for chunk in buffer.chunks(3) { data[i] = chunk[0]; i += 1; data[i] = chunk[1]; i += 1; } Ok(u64::from_be_bytes(data)) } /// Starts measurement /// /// The device starts measuring continuously providing new sample every 1s. If the user gets the signals earlier, /// the same values are returned. #[inline] pub fn start_measurement(&mut self) -> Result<&Self, Error<E>> { self.write_command(Command::StartMeasurement)?; Ok(self) } /// Stops measurement /// /// Stops running the measurements. The user will need to wait 50ms until the device is ready again. #[inline] pub fn stop_measurement(&mut self) -> Result<&Self, Error<E>> { self.write_command(Command::StopMeasurement)?; Ok(self) } /// Resets the sensor. /// /// Executes a reset on the device. The caller must wait 100ms before starting to use the device again. #[inline] pub fn reset(&mut self) -> Result<&Self, Error<E>> { self.write_command(Command::Reset)?; Ok(self) } /// Acquires the sensor serial number. /// /// Sensor serial number is only 48-bits long so the remaining 16-bits are zeros. pub fn version(&mut self) -> Result<Version, Error<E>> { let mut version = [0; 12]; self.delayed_read_cmd(Command::GetVersion, &mut version)?; Ok(Version { sw_major_ver: version[0], sw_minor_ver: version[1], debug_state: version[3] != 0, hw_major_ver: version[4], hw_minor_ver: version[6], protocol_major_ver: version[7], protocol_minor_ver: version[9], }) } /// Read the current measured values. /// /// The firmware updates the measurement values every second. Polling data /// faster will return the same values. The first measurement is available one /// second after the start measurement command is issued. Any readout prior to /// this will return zero initialized values. /// /// This method can only be used after calling ['start_measurement']. pub fn get_measurements(&mut self) -> Result<Signals, Error<E>> { let mut data = [0; 9]; self.delayed_read_cmd(Command::GetSignals, &mut data)?; Ok(Signals::parse(&data)) } /// Returns the new measurement results as integers along with the raw voc ticks and uncompensated RH/T values. /// /// This method reads out VOC Index, relative humidity, and temperature (like ['get_measurements']) and additionally /// the raw signal of SGP40 (proportional to the logarithm of the resistance of the MOX layer) as well as relative /// humidity and temperature which are not compensated for temperature offset. The firmware updates the measurement /// values every second. Polling data faster will return the same values. The first measurement is available on /// second after the start measurement command is issued. Any readout prior to this will return zero initialized values. /// /// This method can only be used after calling ['start_measurement']. pub fn get_raw_measurements(&mut self) -> Result<RawSignals, Error<E>> { let mut data = [0; 18]; self.delayed_read_cmd(Command::GetRawSignals, &mut data)?; Ok(RawSignals::parse(&data)) } /// Gets the temperature offset /// /// Gets the temperature compensation offset issues to the device. pub fn get_temperature_offset(&mut self) -> Result<u16, Error<E>> { let mut buffer = [0; 3]; self.delayed_read_cmd(Command::GetTemperatureOffset, &mut buffer)?; Ok(u16::from_be_bytes([buffer[0], buffer[1]])) } /// Sets the temperature offset. /// /// This command sets the temperature offset used for the compensation of subsequent RHT measurements.RawSignals /// The parameter provides the temperature offset (in °C) with a scaling factor of 200, e.g., an output of +400 corresponds to +2.00 °C. #[inline] pub fn set_temperature_offset(&mut self, offset: u16) -> Result<&mut Self, Error<E>> { self.write_command_with_args(Command::SetTemperatureOffset, &offset.to_be_bytes())?; Ok(self) } /// Gets the device serial number /// /// Based on the output, it looks like serial number could be turned into string. /// API is kept as binary for time being to avoid pulling in std libraries pub fn serial(&mut self, serial: &mut [u8;26]) -> Result<&Self, Error<E>> { let mut buffer = [0; 39]; self.delayed_read_cmd(Command::Serial, &mut buffer)?; let mut i = 0; for chunk in buffer.chunks(3) { serial[i] = chunk[0]; i += 1; serial[i] = chunk[1]; i += 1; } Ok(self) } /// Gets VOC states /// /// The returned value can be used to set the states (using the ['set_voc_states command'] after resuming /// sensor operation, e.g., after a short interruption by skipping the initial learning phase of the VOC Algorithm. #[inline] pub fn get_voc_states(&mut self) -> Result<u64, Error<E>> { self.command_ret_u64(Command::GetVocStates) } /// Set VOC states /// /// This sets the states of the VOC Algorithm state, which were retrieved by the ['set_voc_states'] /// command before. This can be used when resuming sensor operation, e.g., after a short interruption /// by skipping the initial learning phase of the VOC Algorithm. #[inline] pub fn set_voc_states(&mut self, data: u64) -> Result<&Self, Error<E>> { self.write_command_with_args(Command::SetVocStates, &data.to_be_bytes())?; Ok(self) } /// Stores the issues parameters /// /// This command stores all parameters previously sent to the slave via the ['set_temperature_offset'] /// and/or the ['set_voc_parameters'] commands to the non-volatile memory of SVM40. These parameters /// will not be erased during reset and will be used by the corresponding algorithms after start-up. /// To reset the storage to factory settings the master has to set all parameters to the default values /// followed by a subsequent call of the ['store_input_parameters'] command. #[inline] pub fn store_input_parameters(&mut self) -> Result<&Self, Error<E>> { self.write_command(Command::StoreInputParameters)?; Ok(self) } /// Acquires VOC parameters /// /// Four 2 byte parameters are returned as one u64 that were used to configure VOC Algorithm #[inline] pub fn get_voc_parameters(&mut self) -> Result<u64, Error<E>> { self.command_ret_u64(Command::GetVocParameters) } /// Sets VOC parameters /// /// The parameters are used to tune VOC Algorithm. Consult the vendor for the details. #[inline] pub fn set_voc_parameters(&mut self, data: u64) -> Result<&Self, Error<E>>{ self.write_command_with_args(Command::SetVocParameters, &data.to_be_bytes())?; Ok(self) } } // Testing is focused on checking the primitive transactions. It is assumed that during // the real sensor testing, the basic flows in the command structure has been caught. #[cfg(test)] mod tests { use embedded_hal_mock as hal; use self::hal::delay::MockNoop as DelayMock; use self::hal::i2c::{Mock as I2cMock, Transaction}; use super::*; const SVM40_ADD:u8 = 0x6a; /// Tests that the commands without parameters work #[test] fn test_basic_command() { let (cmd, _) = Command::StartMeasurement.as_tuple(); let expectations = [ Transaction::write(SVM40_ADD, cmd.to_be_bytes().to_vec()) ]; let mock = I2cMock::new(&expectations); let mut sensor = Svm40::new(mock, SVM40_ADD, DelayMock); sensor.start_measurement().unwrap(); } /// Test the `serial` function #[test] fn test_basic_read() { let (cmd, _) = Command::GetTemperatureOffset.as_tuple(); let expectations = [ Transaction::write(SVM40_ADD, cmd.to_be_bytes().to_vec()), Transaction::read(SVM40_ADD, vec![0x00, 0x00, 0x81]), ]; let mock = I2cMock::new(&expectations); let mut sensor = Svm40::new(mock, SVM40_ADD, DelayMock); let offset = sensor.get_temperature_offset().unwrap(); assert_eq!(offset, 0); } #[test] fn test_crc_error() { let (cmd, _) = Command::GetTemperatureOffset.as_tuple(); let expectations = [ Transaction::write(SVM40_ADD, cmd.to_be_bytes().to_vec()), Transaction::read(SVM40_ADD, vec![0xD4, 0x00, 0x00]), ]; let mock = I2cMock::new(&expectations); let mut sensor = Svm40::new(mock, SVM40_ADD, DelayMock); match sensor.get_temperature_offset() { Err(Error::Crc) => {}, Err(_) => panic!("Unexpected error in CRC test"), Ok(_) => panic!("Unexpected success in CRC test") } } #[test] fn test_version() { let (cmd, _) = Command::GetVersion.as_tuple(); let expectations = [ Transaction::write(SVM40_ADD, cmd.to_be_bytes().to_vec()), Transaction::read(SVM40_ADD, vec![0x01, 0x00, 0x75, 0x00, 0x01, 0xb0, 0x00, 0x01, 0xb0, 0x00, 0x00, 0x81]), ]; let mock = I2cMock::new(&expectations); let mut sensor = Svm40::new(mock, SVM40_ADD, DelayMock); let version = sensor.version().unwrap(); assert_eq!(version.sw_major_ver, 1); assert_eq!(version.sw_minor_ver, 0); assert_eq!(version.debug_state, false); assert_eq!(version.hw_major_ver, 1); assert_eq!(version.hw_minor_ver, 0); assert_eq!(version.protocol_major_ver, 1); assert_eq!(version.protocol_minor_ver, 0); } #[test] fn test_u64_read() { let (cmd, _) = Command::GetVocStates.as_tuple(); let expectations = [ Transaction::write(SVM40_ADD, cmd.to_be_bytes().to_vec()), Transaction::read(SVM40_ADD, vec![0x01, 0x02, 0x17, 0x03, 0x04, 0x68, 0x05, 0x06, 0x50, 0x07, 0x08, 0x96]), ]; let mock = I2cMock::new(&expectations); let mut sensor = Svm40::new(mock, SVM40_ADD, DelayMock); let states = sensor.get_voc_states().unwrap(); println!("States:{:x}", states); assert_eq!(0x102030405060708, states); } #[test] fn test_u64_write() { let (cmd, _) = Command::SetVocStates.as_tuple(); let mut data = cmd.to_be_bytes().to_vec(); data.append(&mut vec![0x01, 0x02, 0x17, 0x03, 0x04, 0x68, 0x05, 0x06, 0x50, 0x07, 0x08, 0x96]); let expectations = [ Transaction::write(SVM40_ADD, data), ]; let mock = I2cMock::new(&expectations); let mut sensor = Svm40::new(mock, SVM40_ADD, DelayMock); sensor.set_voc_states(0x102030405060708_u64).unwrap(); } }