# SPDX-FileCopyrightText: 2017 Tony DiCola for Adafruit Industries
#
# SPDX-License-Identifier: MIT
"""
`adafruit_max9744`
====================================================
CircuitPython module for the MAX9744 20W class D amplifier. See
examples/simpletest.py for a demo of the usage.
* Author(s): Tony DiCola
Implementation Notes
--------------------
**Hardware:**
* Adafruit `MAX9744 Stereo 20W Class D Audio Amplifier
<https://www.adafruit.com/product/1752>`_ (Product ID: 1752)
**Software and Dependencies:**
* Adafruit CircuitPython firmware for the ESP8622 and M0-based boards:
https://github.com/adafruit/circuitpython/releases
"""
try:
# Imports only used for typing.
# First check if the the typing module exists, to avoid loading
# other typing-only modules when running under circuitpython.
import typing # pylint: disable=unused-import
import busio
except ImportError:
pass
from micropython import const
__version__ = "0.0.0+auto.0"
__repo__ = "https://github.com/adafruit/Adafruit_CircuitPython_MAX9744.git"
# Internal constants:
_MAX9744_DEFAULT_ADDRESS = const(0b01001011)
_MAX9744_COMMAND_VOLUME = const(0b00000000)
_MAX9744_COMMAND_FILTERLESS = const(0b01000000)
_MAX9744_COMMAND_CLASSIC_PWM = const(0b01000001)
_MAX9744_COMMAND_VOLUME_UP = const(0b11000100)
_MAX9744_COMMAND_VOLUME_DOWN = const(0b11000101)
[docs]
class MAX9744:
"""MAX9744 20 watt class D amplifier.
:param i2c: The I2C bus for the device.
:param address: (Optional) The address of the device if it has been overridden from the
default with the AD1, AD2 pins.
"""
# Global buffer for writing data. This saves memory use and prevents
# heap fragmentation. However this is not thread-safe or re-entrant by
# design!
_BUFFER = bytearray(1)
def __init__(self, i2c: busio.I2C, *, address: int = _MAX9744_DEFAULT_ADDRESS):
# This device doesn't use registers and instead just accepts a single
# command string over I2C. As a result we don't use bus device or
# other abstractions and just talk raw I2C protocol.
self._i2c = i2c
self._address = address
def _write(self, val: int) -> None:
# Perform a write to update the amplifier state.
try:
# Make sure bus is locked before write.
while not self._i2c.try_lock():
pass
# Build bytes to send to device with updated value.
self._BUFFER[0] = val & 0xFF
self._i2c.writeto(self._address, self._BUFFER)
finally:
# Ensure bus is always unlocked.
self._i2c.unlock()
def _set_volume(self, volume: int) -> None:
# Set the volume to the specified level (0-63).
assert 0 <= volume <= 63
self._write(_MAX9744_COMMAND_VOLUME | (volume & 0x3F))
# pylint: disable=line-too-long
volume = property(
None,
_set_volume,
None,
"Set the volume of the amplifier. Specify a value from 0-63 where 0 is muted/off and 63 is maximum volume.",
)
# pylint: enable=line-too-long
[docs]
def volume_up(self) -> None:
"""Increase the volume by one level."""
self._write(_MAX9744_COMMAND_VOLUME_UP)
[docs]
def volume_down(self) -> None:
"""Decrease the volume by one level."""
self._write(_MAX9744_COMMAND_VOLUME_DOWN)