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adafruit_emc2101.py
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# SPDX-FileCopyrightText: Copyright (c) 2020 Bryan Siepert for Adafruit Industries
#
# SPDX-License-Identifier: MIT
"""
`adafruit_emc2101`
================================================================================
Brushless fan controller
* Author(s): Bryan Siepert
Implementation Notes
--------------------
**Hardware:**
* `Adafruit EMC2101 Breakout <https://adafruit.com/product/4808>`_
**Software and Dependencies:**
* Adafruit CircuitPython firmware for the supported boards:
https://github.com/adafruit/circuitpython/releases
# * Adafruit's Bus Device library: https://github.com/adafruit/Adafruit_CircuitPython_BusDevice
# * Adafruit's Register library: https://github.com/adafruit/Adafruit_CircuitPython_Register
"""
from micropython import const
from adafruit_register.i2c_struct import ROUnaryStruct, UnaryStruct
from adafruit_register.i2c_bit import RWBit
from adafruit_register.i2c_bits import RWBits
import adafruit_bus_device.i2c_device as i2cdevice
__version__ = "0.0.0-auto.0"
__repo__ = "https://github.com/adafruit/Adafruit_CircuitPython_EMC2101.git"
_INTERNAL_TEMP = const(0x00)
_EXTERNAL_TEMP_MSB = const(0x01)
_EXTERNAL_TEMP_LSB = const(0x10)
_STATUS = const(0x02)
_REG_CONFIG = const(0x03)
_TEMP_FORCE = const(0x0C)
_TACH_LSB = const(0x46)
_TACH_MSB = const(0x47)
_TACH_LIMIT_LSB = const(0x48)
_TACH_LIMIT_MSB = const(0x49)
_FAN_CONFIG = const(0x4A)
_FAN_SPINUP = const(0x4B)
_REG_FAN_SETTING = const(0x4C)
_PWM_FREQ = const(0x4D)
_PWM_DIV = const(0x4E)
_LUT_HYSTERESIS = const(0x4F)
_TEMP_FILTER = const(0xBF)
_REG_PARTID = const(0xFD) # 0x16
_REG_MFGID = const(0xFE) # 0xFF16
MAX_LUT_SPEED = 0x3F # 6-bit value
MAX_LUT_TEMP = 0x7F # 7-bit
_I2C_ADDR = const(0x4C)
_FAN_RPM_DIVISOR = const(5400000)
_TEMP_LSB = 0.125
def _speed_to_lsb(percentage):
return round((percentage / 100.0) * MAX_LUT_SPEED)
def _lsb_to_speed(lsb_speed):
return round((lsb_speed / MAX_LUT_SPEED) * 100.0)
class FanSpeedLUT:
"""A class used to provide a dict-like interface to the EMC2101's Temperature to Fan speed
Look Up Table"""
# seems like a pain but ¯\_(ツ)_/¯
_fan_lut_t1 = UnaryStruct(0x50, "<B")
_fan_lut_s1 = UnaryStruct(0x51, "<B")
_fan_lut_t2 = UnaryStruct(0x52, "<B")
_fan_lut_s2 = UnaryStruct(0x53, "<B")
_fan_lut_t3 = UnaryStruct(0x54, "<B")
_fan_lut_s3 = UnaryStruct(0x55, "<B")
_fan_lut_t4 = UnaryStruct(0x56, "<B")
_fan_lut_s4 = UnaryStruct(0x57, "<B")
_fan_lut_t5 = UnaryStruct(0x58, "<B")
_fan_lut_s5 = UnaryStruct(0x59, "<B")
_fan_lut_t6 = UnaryStruct(0x5A, "<B")
_fan_lut_s6 = UnaryStruct(0x5B, "<B")
_fan_lut_t7 = UnaryStruct(0x5C, "<B")
_fan_lut_s7 = UnaryStruct(0x5D, "<B")
_fan_lut_t8 = UnaryStruct(0x5E, "<B")
_fan_lut_s8 = UnaryStruct(0x5F, "<B")
_lut_speed_setters = [
_fan_lut_s1,
_fan_lut_s2,
_fan_lut_s3,
_fan_lut_s4,
_fan_lut_s5,
_fan_lut_s6,
_fan_lut_s7,
_fan_lut_s8,
]
_lut_temp_setters = [
_fan_lut_t1,
_fan_lut_t2,
_fan_lut_t3,
_fan_lut_t4,
_fan_lut_t5,
_fan_lut_t6,
_fan_lut_t7,
_fan_lut_t8,
]
def __init__(self, fan_obj):
self.emc_fan = fan_obj
self.lut_values = {}
self.i2c_device = fan_obj.i2c_device
def __getitem__(self, index):
if not isinstance(index, int):
raise IndexError
if not index in self.lut_values:
raise IndexError
return self.lut_values[index]
def __setitem__(self, index, value):
if not isinstance(index, int):
raise IndexError
self.lut_values[index] = value
self._set_lut(self.lut_values)
def __repr__(self):
"""return the official string representation of the LUT"""
return "FanSpeedLUT <%x>" % id(self)
def __str__(self):
"""return the official string representation of the LUT"""
value_strs = []
lut_keys = list(self.lut_values.keys())
lut_keys.sort()
for temp in lut_keys:
fan_drive = self.lut_values[temp]
value_strs.append("%d deg C => %.1f%% duty cycle" % (temp, fan_drive))
return "\n".join(value_strs)
def __len__(self):
return len(self.lut_values)
# this function does a whole lot of work to organized the user-supplied lut dict into
# their correct spot within the lut table as pairs of set registers, sorted with the lowest
# temperature first
def _set_lut(self, lut_dict):
lut_keys = list(lut_dict.keys())
lut_size = len(lut_dict)
# Make sure we're not going to try to set more entries than we have slots
if lut_size > 8:
raise AttributeError("LUT can only contain a maximum of 8 items")
# we want to assign the lowest temperature to the lowest LUT slot, so we sort the keys/temps
for k in lut_keys:
# Verify that the value is a correct amount
lut_value = lut_dict[k]
if lut_value > 100.0 or lut_value < 0:
raise AttributeError("LUT values must be a fan speed from 0-100%")
# add the current temp/speed to our internal representation
self.lut_values[k] = lut_value
current_mode = self.emc_fan.lut_enabled
# Disable the lut to allow it to be updated
self.emc_fan.lut_enabled = False
# get and sort the new lut keys so that we can assign them in order
lut_keys = list(self.lut_values.keys())
lut_keys.sort()
for idx in range(lut_size):
current_temp = lut_keys[idx]
current_speed = _speed_to_lsb(self.lut_values[current_temp])
getattr(self, "_fan_lut_t%d" % (idx + 1)).__set__(self, current_temp)
getattr(self, "_fan_lut_s%d" % (idx + 1)).__set__(self, current_speed)
# self.emc_fan._lut_temp_setters[idx].__set__(self.emc_fan, current_temp)
# self.emc_fan._lut_speed_setters[idx].__set__(self.emc_fan, current_speed)
# Set the remaining LUT entries to the default (Temp/Speed = max value)
for idx in range(8)[lut_size:]:
getattr(self, "_fan_lut_t%d" % (idx + 1)).__set__(self, MAX_LUT_TEMP)
getattr(self, "_fan_lut_s%d" % (idx + 1)).__set__(self, MAX_LUT_SPEED)
self.emc_fan.lut_enabled = current_mode
class CV:
"""struct helper"""
@classmethod
def add_values(cls, value_tuples):
"creates CV entires"
cls.string = {}
cls.lsb = {}
for value_tuple in value_tuples:
name, value, string, lsb = value_tuple
setattr(cls, name, value)
cls.string[value] = string
cls.lsb[value] = lsb
@classmethod
def is_valid(cls, value):
"Returns true if the given value is a member of the CV"
return value in cls.string
class ConversionRate(CV):
"""Options for ``accelerometer_data_rate`` and ``gyro_data_rate``"""
ConversionRate.add_values(
(
("RATE_1_16", 0, str(1 / 16.0), None),
("RATE_1_8", 1, str(1 / 8.0), None),
("RATE_1_4", 2, str(1 / 4.0), None),
("RATE_1_2", 3, str(126.0), None),
("RATE_1", 4, str(1.0), None),
("RATE_2", 5, str(2.0), None),
("RATE_4", 6, str(4.0), None),
("RATE_8", 7, str(8.0), None),
("RATE_16", 8, str(16.0), None),
("RATE_32", 9, str(32.0), None),
)
)
class SpinupDrive(CV):
"""Options for ``spinup_drive``"""
SpinupDrive.add_values(
(
("BYPASS", 0, "Disabled", None),
("DRIVE_50", 1, "50% Duty Cycle", None),
("DRIVE_75", 2, "25% Duty Cycle", None),
("DRIVE_100", 3, "100% Duty Cycle", None),
)
)
class SpinupTime(CV):
"""Options for ``spinup_time``"""
SpinupTime.add_values(
(
("BYPASS", 0, "Disabled", None),
("SPIN_0_05_SEC", 1, "0.05 seconds", None),
("SPIN_0_1_SEC", 2, "0.1 seconds", None),
("SPIN_0_2_SEC", 3, "0.2 seconds", None),
("SPIN_0_4_SEC", 4, "0.4 seconds", None),
("SPIN_0_8_SEC", 5, "0.8 seconds", None),
("SPIN_1_6_SEC", 6, "1.6 seconds", None),
("SPIN_3_2_SEC", 7, "3.2 seconds", None),
)
)
class EMC2101: # pylint: disable=too-many-instance-attributes
"""Driver for the EMC2101 Fan Controller.
:param ~busio.I2C i2c_bus: The I2C bus the EMC is connected to.
"""
_part_id = ROUnaryStruct(_REG_PARTID, "<B")
_mfg_id = ROUnaryStruct(_REG_MFGID, "<B")
_int_temp = ROUnaryStruct(_INTERNAL_TEMP, "<b")
# IMPORTANT! the sign bit for the external temp is in the msbyte so mark it as signed
# and lsb as unsigned
_ext_temp_msb = ROUnaryStruct(_EXTERNAL_TEMP_MSB, "<b")
_ext_temp_lsb = ROUnaryStruct(_EXTERNAL_TEMP_LSB, "<B")
# _tach_read = ROUnaryStruct(_TACH_LSB, "<H")
_tach_read_lsb = ROUnaryStruct(_TACH_LSB, "<B")
_tach_read_msb = ROUnaryStruct(_TACH_MSB, "<B")
_tach_mode_enable = RWBit(_REG_CONFIG, 2)
_tach_limit_lsb = UnaryStruct(_TACH_LIMIT_LSB, "<B")
_tach_limit_msb = UnaryStruct(_TACH_LIMIT_MSB, "<B")
# temp used to override current external temp measurement
forced_ext_temp = UnaryStruct(_TEMP_FORCE, "<b")
"""The value that the external temperature will be forced to read when `forced_temp_enabled` is
set. This can be used to test the behavior of the LUT without real temperature changes"""
forced_temp_enabled = RWBit(_FAN_CONFIG, 6)
"""When True, the external temperature measurement will always be read as the value in
`forced_ext_temp`"""
_fan_setting = UnaryStruct(_REG_FAN_SETTING, "<B")
_fan_lut_prog = RWBit(_FAN_CONFIG, 5)
invert_fan_output = RWBit(_FAN_CONFIG, 4)
"""When set to True, the magnitude of the fan output signal is inverted, making 0 the maximum
value and 100 the minimum value"""
_fan_pwm_clock_select = RWBit(_FAN_CONFIG, 3)
_fan_pwm_clock_override = RWBit(_FAN_CONFIG, 2)
_pwm_freq = RWBits(5, _PWM_FREQ, 0)
_pwm_freq_div = UnaryStruct(_PWM_DIV, "<B")
dac_output_enabled = RWBit(_REG_CONFIG, 4)
"""When set, the fan control signal is output as a DC voltage instead of a PWM signal"""
_conversion_rate = RWBits(4, 0x04, 0)
# fan spin-up
_spin_drive = RWBits(2, _FAN_SPINUP, 3)
_spin_time = RWBits(3, _FAN_SPINUP, 0)
_spin_tach_limit = RWBit(_FAN_SPINUP, 5)
lut_temperature_hysteresis = UnaryStruct(_LUT_HYSTERESIS, "<B")
"""The amount of hysteresis in Degrees celcius of hysteresis applied to temperature readings
used for the LUT. As the temperature drops, the controller will switch to a lower LUT entry when
the measured value is belowthe lower entry's threshold, minus the hysteresis value"""
def __init__(self, i2c_bus):
self.i2c_device = i2cdevice.I2CDevice(i2c_bus, _I2C_ADDR)
if not self._part_id in [0x16, 0x28] or self._mfg_id != 0x5D:
raise AttributeError("Cannot find a EMC2101")
# self._lut = {}
self.initialize()
self._lut = FanSpeedLUT(self)
def initialize(self):
"""Reset the controller to an initial default configuration"""
self._tach_mode_enable = True
self.lut_enabled = False
self._enabled_forced_temp = False
self._fan_pwm_clock_override = True
self._spin_tach_limit = False
@property
def internal_temperature(self):
"""The temperature as measured by the EMC2101's internal 8-bit temperature sensor"""
return self._int_temp
@property
def external_temperature(self):
"""The temperature measured using the external diode"""
temp_lsb = self._ext_temp_lsb
temp_msb = self._ext_temp_msb
full_tmp = (temp_msb << 8) | temp_lsb
full_tmp >>= 5
full_tmp *= 0.125
return full_tmp
def set_pwm_clock(self, use_preset=False, use_slow=False):
"""
Select the PWM clock source, chosing between two preset clocks or by configuring the
clock using `pwm_frequency` and `pwm_frequency_divisor`.
:param bool use_preset:
True: Select between two preset clock sources
False: The PWM clock is set by `pwm_frequency` and `pwm_frequency_divisor`
:param bool use_slow:
True: Use the 1.4kHz clock
False: Use the 360kHz clock.
:type priority: integer or None
:return: None
:raises AttributeError: if use_preset is not a `bool`
:raises AttributeError: if use_slow is not a `bool`
"""
if not isinstance(use_preset, bool):
raise AttributeError("use_preset must be given a bool")
if not isinstance(use_slow, bool):
raise AttributeError("use_slow_pwm must be given a bool")
self._fan_pwm_clock_override = not use_preset
self._fan_pwm_clock_select = use_slow
@property
def pwm_frequency(self):
"""Selects the base clock frequency used for the fan PWM output"""
return self._pwm_freq
@pwm_frequency.setter
def pwm_frequency(self, value):
if value < 0 or value > 0x1F:
raise AttributeError("pwm_frequency must be from 0-31")
self._pwm_freq = value
@property
def pwm_frequency_divisor(self):
"""The Divisor applied to the PWM frequency to set the final frequency"""
return self._pwm_freq_div
@pwm_frequency_divisor.setter
def pwm_frequency_divisor(self, divisor):
if divisor < 0 or divisor > 255:
raise AttributeError("pwm_frequency_divisor must be from 0-255")
self._pwm_freq_div = divisor
@property
def fan_speed(self):
"""The current speed in Revolutions per Minute (RPM)"""
val = self._tach_read_lsb
val |= self._tach_read_msb << 8
return _FAN_RPM_DIVISOR / val
@property
def manual_fan_speed(self):
"""The fan speed used while the LUT is being updated and is unavailable. The speed is
given as the fan's PWM duty cycle represented as a float percentage.
The value roughly approximates the percentage of the fan's maximum speed"""
raw_setting = self._fan_setting & MAX_LUT_SPEED
return (raw_setting / MAX_LUT_SPEED) * 100
@manual_fan_speed.setter
def manual_fan_speed(self, fan_speed):
if fan_speed not in range(0, 101):
raise AttributeError("manual_fan_speed must be from 0-100 ")
# convert from a percentage to an lsb value
percentage = fan_speed / 100.0
fan_speed_lsb = round(percentage * MAX_LUT_SPEED)
lut_disabled = self._fan_lut_prog
self._fan_lut_prog = True
self._fan_setting = fan_speed_lsb
self._fan_lut_prog = lut_disabled
@property
def lut_enabled(self):
"""Enable or disable the internal look up table used to map a given temperature
to a fan speed. When the LUT is disabled fan speed can be changed with `manual_fan_speed`"""
return not self._fan_lut_prog
@lut_enabled.setter
def lut_enabled(self, enable_lut):
self._fan_lut_prog = not enable_lut
@property
def lut(self):
"""The dict-like representation of the LUT"""
return self._lut
@property
def tach_limit(self):
"""The maximum /minimum speed expected for the fan"""
low = self._tach_limit_lsb
high = self._tach_limit_msb
return _FAN_RPM_DIVISOR / ((high << 8) | low)
@tach_limit.setter
def tach_limit(self, new_limit):
num = int(_FAN_RPM_DIVISOR / new_limit)
self._tach_limit_lsb = num & 0xFF
self._tach_limit_msb = (num >> 8) & 0xFF
@property
def spinup_time(self):
"""The amount of time the fan will spin at the current set drive strength.
Must be a `SpinupTime`"""
return self._spin_time
@spinup_time.setter
def spinup_time(self, spin_time):
if not SpinupTime.is_valid(spin_time):
raise AttributeError("spinup_time must be a SpinupTime")
self._spin_time = spin_time
@property
def spinup_drive(self):
"""The drive strengh of the fan on spinup in % max RPM"""
return self._spin_drive
@spinup_drive.setter
def spinup_drive(self, spin_drive):
if not SpinupDrive.is_valid(spin_drive):
raise AttributeError("spinup_drive must be a SpinupDrive")
self._spin_drive = spin_drive
@property
def conversion_rate(self):
"""The rate at which temperature measurements are taken. Must be a `ConversionRate`"""
return self._conversion_rate
@conversion_rate.setter
def conversion_rate(self, rate):
if not ConversionRate.is_valid(rate):
raise AttributeError("conversion_rate must be a `ConversionRate`")
self._conversion_rate = rate