NAME

Device::Chip::SCD4x - chip driver for SCD40 and SCD41

SYNOPSIS

   use Device::Chip::SCD4x;
   use Future::AsyncAwait;

   my $chip = Device::Chip::SCD4x->new;
   await $chip->mount( Device::Chip::Adapter::...->new );

   await $chip->start_periodic_measurement;

   while(1) {
      await Future::IO->sleep(1);

      my ( $co2, $temp, $humid ) = await $chip->maybe_read_measurement
         or next;

      printf "CO2 concentration=%dppm  ", $co2;
      printf "Temperature=%.2fC  ", $temp;
      printf "Humidity=%.2f%%\n", $hum;
   }

DESCRIPTION

This Device::Chip subclass provides specific communication to a Sensirion SCD40 or SCD41 attached to a computer via an I²C adapter.

The reader is presumed to be familiar with the general operation of this chip; the documentation here will not attempt to explain or define chip-specific concepts or features, only the use of this module to access them.

MOUNT PARAMETERS

addr

The I²C address of the device. Can be specified in decimal, octal or hex with leading 0 or 0x prefixes.

METHODS

The following methods documented in an await expression return Future instances.

read_config

   $config = await $chip->read_config;

Returns a HASH reference containing the compensation values from chip config.

   temperature_offset # in degrees C
   sensor_altitude    # in metres
   ambient_pressure   # in hPa

start_periodic_measurement

   await $chip->start_periodic_measurement;

Starts periodic measurement mode.

read_measurement

   ( $co2concentration, $temperature, $humidity ) = await $chip->read_measurement();

Returns the latest sensor reading values. Returns a 3-element list, containing the CO₂ concentration in PPM, temperature in degrees C, and humidity in %RH.

maybe_read_measurement

   ( $co2concentration, $temperature, $humidity ) = await $chip->maybe_read_measurement();

If the sensor has a new measurement ready, returns it. Otherwise, returns the last successful measurement reading. After initial startup, this will return an empty list before the first reading is available.

get_serial_number

   $bytes = await $chip->get_serial_number;

Returns a 6-byte encoding of the chip's internal serial number.

AUTHOR

Paul Evans <leonerd@leonerd.org.uk>