NAME

Device::Chip::MPL3115A2 - chip driver for a MPL3115A2

SYNOPSIS

   use Device::Chip::MPL3115A2;
   use Future::AsyncAwait;

   my $chip = Device::Chip::MPL3115A2->new;
   await $chip->mount( Device::Chip::Adapter::...->new );

   printf "Current pressure is %.2f kPa\n",
      await $chip->read_pressure;

DESCRIPTION

This Device::Chip subclass provides specific communication to a Freescale Semiconductor MPL3115A2 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.

ACCESSORS

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

read_config

   $config = await $chip->read_config;

Returns a HASH reference of the contents of control registers CTRL_REG1 to CTRL_REG3, using fields named from the data sheet.

   SBYB => "STANDBY" | "ACTIVE"
   OST  => 0 | 1
   RST  => 0 | 1
   OS   => 1 | 2 | 4 | ... | 64 | 128
   RAW  => 0 | 1
   ALT  => 0 | 1

   ST          => 1 | 2 | 4 | ... | 16384 | 32768
   ALARM_SEL   => 0 | 1
   LOAD_OUTPUT => 0 | 1

   IPOL1  => 0 | 1
   PP_OD1 => 0 | 1
   IPOL2  => 0 | 1
   PP_OD2 => 0 | 1

change_config

   await $chip->change_config( %changes );

Writes updates to the control registers CTRL_REG1 to CTRL_REG3. This will be performed as a read-modify-write operation, so any fields not given as arguments to this method will retain their current values.

Note that these two methods use a cache of configuration bytes to make subsequent modifications more efficient. This cache will not respect the "one-shot" nature of the OST and RST bits.

get_sealevel_pressure

set_sealevel_pressure

   $pressure = await $chip->get_sealevel_pressure;

   await $chip->set_sealevel_pressure( $pressure );

Read or write the barometric pressure calibration register which is used to convert pressure to altitude when the chip is in altimeter mode, in Pascals. The default value is 101,326 Pa.

read_pressure

   $pressure = await $chip->read_pressure;

Returns the value of the OUT_P_* registers, suitably converted into Pascals. (The chip must be in barometer mode and must not be in RAW mode for the conversion to work).

read_altitude

   $altitude = await $chip->read_altitude;

Returns the value of the OUT_P_* registers, suitably converted into metres. (The chip must be in altimeter mode and must not be in RAW mode for the conversion to work).

read_temperature

   $temperature = await $chip->read_temperature;

Returns the value of the OUT_T_* registers, suitable converted into degrees C. (The chip must not be in RAW mode for the conversion to work).

read_min_pressure

read_max_pressure

   $pressure = await $chip->read_min_pressure;

   $pressure = await $chip->read_max_pressure;

Returns the values of the P_MIN and P_MAX registers, suitably converted into Pascals.

clear_min_pressure

clear_max_pressure

   await $chip->clear_min_pressure;

   await $chip->clear_max_pressure;

Clear the P_MIN or P_MAX registers, resetting them to start again from the next measurement.

read_min_altitude

read_max_altitude

   $altitude = await $chip->read_min_altitude;

   $altitude = await $chip->read_max_altitude;

Returns the values of the P_MIN and P_MAX registers, suitably converted into metres.

clear_min_altitude

clear_max_altitude

   await $chip->clear_min_altitude;

   await $chip->clear_max_altitude;

Clear the P_MIN or P_MAX registers, resetting them to start again from the next measurement.

read_min_temperature

read_max_temperature

   $temperature = await $chip->read_min_temperature;

   $temperature = await $chip->read_max_temperature;

Returns the values of the T_MIN and T_MAX registers, suitably converted into metres.

clear_min_temperature

clear_max_temperature

   await $chip->clear_min_temperature;

   await $chip->clear_max_temperature;

Clear the T_MIN or T_MAX registers, resetting them to start again from the next measurement.

METHODS

check_id

   await $chip->check_id;

Reads the WHO_AM_I register and checks for a valid ID result. The returned future fails if the expected result is not received.

start_oneshot

   await $chip->start_oneshot;

Sets the OST bit of CTRL_REG1 to start a one-shot measurement when in standby mode. After calling this method you will need to use busywait_oneshot to wait for the measurement to finish, or rely somehow on the interrupts.

busywait_oneshot

   await $chip->busywait_oneshot;

Repeatedly reads the OST bit of CTRL_REG1 until it becomes clear.

oneshot

   await $chip->oneshot;

A convenient wrapper around start_oneshot and busywait_oneshot.

AUTHOR

Paul Evans <leonerd@leonerd.org.uk>

cpanm Device::Chip::MPL3115A2

perl -MCPAN -e shell
install Device::Chip::MPL3115A2