aht10: Added support for AHT10 ambient temperature sensor (#6138)

This commit adds support for the I2C-based AHT10 ambient temperature sensor. The sensor comes pre-calibrated and has a fairly simple command interface, so the interface class is in-turn relatively simple. So far this has been tested on a BTT GTR 1.0 MCU board (STM32F4), and seems to work fine.

Signed-off-by: Scott Mudge <mail@scottmudge.com>

2 files changed, 163 insertions, 0 deletions

diff --git a/klippy/extras/aht10.py b/klippy/extras/aht10.py
new file mode 100644
index 00000000..b6cac2e3
--- /dev/null
+++ b/klippy/extras/aht10.py
@@ -0,0 +1,160 @@
+# AHT10 I2c-based humiditure sensor support
+#
+# Copyright (C) 2023 Scott Mudge <mail@scottmudge.com>
+#
+# This file may be distributed under the terms of the GNU GPLv3 license.
+import logging
+from . import bus
+
+######################################################################
+# Compatible Sensors:
+#       AHT10      -    Tested w/ BTT GTR 1.0 MCU on i2c3
+######################################################################
+
+AHT10_I2C_ADDR= 0x38
+
+AHT10_COMMANDS = {
+    'INIT'              :[0xE1, 0x08, 0x00],
+    'MEASURE'           :[0xAC, 0x33, 0x00],
+    'RESET'             :[0xBA, 0x08, 0x00]
+}
+
+AHT10_MAX_BUSY_CYCLES= 5
+
+class AHT10:
+    def __init__(self, config):
+        self.printer = config.get_printer()
+        self.name = config.get_name().split()[-1]
+        self.reactor = self.printer.get_reactor()
+        self.i2c = bus.MCU_I2C_from_config(
+            config, default_addr=AHT10_I2C_ADDR, default_speed=100000)
+        self.report_time = config.getint('aht10_report_time',30,minval=5)
+        self.temp = self.min_temp = self.max_temp = self.humidity = 0.
+        self.sample_timer = self.reactor.register_timer(self._sample_aht10)
+        self.printer.add_object("aht10 " + self.name, self)
+        self.printer.register_event_handler("klippy:connect",
+                                            self.handle_connect)
+        self.is_calibrated  = False
+        self.init_sent = False
+
+    def handle_connect(self):
+        self._init_aht10()
+        self.reactor.update_timer(self.sample_timer, self.reactor.NOW)
+
+    def setup_minmax(self, min_temp, max_temp):
+        self.min_temp = min_temp
+        self.max_temp = max_temp
+
+    def setup_callback(self, cb):
+        self._callback = cb
+
+    def get_report_time_delta(self):
+        return self.report_time
+
+    def _make_measurement(self):
+        if not self.init_sent:
+            return False
+
+        data = None
+
+        is_busy = True
+        cycles = 0
+
+        try:
+            while is_busy:
+                # Check if we're constantly busy. If so, send soft-reset
+                # and issue warning.
+                if is_busy and cycles > AHT10_MAX_BUSY_CYCLES:
+                    logging.warning("aht10: device reported busy after " +
+                        "%d cycles, resetting device"% AHT10_MAX_BUSY_CYCLES)
+                    self._reset_device()
+                    data = None
+                    break
+
+                cycles += 1
+                # Write command for updating temperature+status bit
+                self.i2c.i2c_write(AHT10_COMMANDS['MEASURE'])
+                # Wait 110ms after first read, 75ms minimum
+                self.reactor.pause(self.reactor.monotonic() + .110)
+
+                # Read data
+                read = self.i2c.i2c_read([], 6)
+                if read is None:
+                    logging.warning("aht10: received data from" +
+                                    " i2c_read is None")
+                    continue
+                data = bytearray(read['response'])
+                if len(data) < 6:
+                    logging.warning("aht10: received bytes less than" +
+                                    " expected 6 [%d]"%len(data))
+                    continue
+
+                self.is_calibrated = True if (data[0] & 0b00000100) else False
+                is_busy = True if (data[0] & 0b01000000) else False
+
+            if is_busy:
+                return False
+        except Exception as e:
+            logging.exception("aht10: exception encountered" +
+                              " reading data: %s"%str(e))
+            return False
+
+        temp = ((data[3] & 0x0F) << 16) | (data[4] << 8) | data[5]
+        self.temp = ((temp*200) / 1048576) - 50
+        hum = ((data[1] << 16) | (data[2] << 8) | data[3]) >> 4
+        self.humidity = int(hum * 100 / 1048576)
+
+        # Clamp humidity
+        if (self.humidity > 100):
+            self.humidity = 100
+        elif (self.humidity < 0):
+            self.humidity = 0
+
+        return True
+
+    def _reset_device(self):
+        if not self.init_sent:
+            return
+
+        # Reset device
+        self.i2c.i2c_write(AHT10_COMMANDS['RESET'])
+        # Wait 100ms after reset
+        self.reactor.pause(self.reactor.monotonic() + .10)
+
+    def _init_aht10(self):
+        # Init device
+        self.i2c.i2c_write(AHT10_COMMANDS['INIT'])
+        # Wait 100ms after init
+        self.reactor.pause(self.reactor.monotonic() + .10)
+        self.init_sent = True
+
+        if self._make_measurement():
+            logging.info("aht10: successfully initialized, initial temp: " +
+                         "%.3f, humidity: %.3f"%(self.temp, self.humidity))
+
+    def _sample_aht10(self, eventtime):
+        if not self._make_measurement():
+            self.temp = self.humidity = .0
+            return self.reactor.NEVER
+
+        if self.temp < self.min_temp or self.temp > self.max_temp:
+            self.printer.invoke_shutdown(
+                "AHT10 temperature %0.1f outside range of %0.1f:%.01f"
+                % (self.temp, self.min_temp, self.max_temp))
+
+        measured_time = self.reactor.monotonic()
+        print_time = self.i2c.get_mcu().estimated_print_time(measured_time)
+        self._callback(print_time, self.temp)
+        return measured_time + self.report_time
+
+    def get_status(self, eventtime):
+        return {
+            'temperature': round(self.temp, 2),
+            'humidity': self.humidity,
+        }
+
+
+def load_config(config):
+    # Register sensor
+    pheater = config.get_printer().lookup_object("heaters")
+    pheater.add_sensor_factory("AHT10", AHT10)
diff --git a/klippy/extras/temperature_sensors.cfg b/klippy/extras/temperature_sensors.cfg
index ebee3089..7e0d918f 100644
--- a/klippy/extras/temperature_sensors.cfg
+++ b/klippy/extras/temperature_sensors.cfg
@@ -18,6 +18,9 @@
 # Load "SI7013", "SI7020", "SI7021", "SHT21", and "HTU21D" sensors
 [htu21d]
 
+# Load "AHT10"
+[aht10]
+
 # Load "LM75" sensor
 [lm75]