Add mip support

Author: mcauser

README.md

@@ -1,40 +1,114 @@
 # MicroPython AM2320 I2C
 
-A MicroPython library for interfacing with an [Aosong AM2320](http://www.aosong.com/products-32.html) temperature and humidity sensor over I2C.
+A MicroPython library for interfacing with an [Aosong AM2320](http://www.aosong.com/en/products-41.html) temperature and humidity sensor over I2C.
 
 This library focuses on using the I2C interface. The sensor also supports a 1-wire interface, available when pin 4 is connected to GND.
 
-![demo](docs/AM2320.jpg)
+![demo](docs/demo.jpg)
 
-#### Examples
 
-Basic measurement
+## Installation
+
+Using mip via mpremote:
+
+```bash
+$ mpremote mip install github:mcauser/micropython-am2320
+$ mpremote mip install github:mcauser/micropython-am2320/examples
+```
+
+Using mip directly on a WiFi capable board:
+
+```python
+>>> import mip
+>>> mip.install("github:mcauser/micropython-am2320")
+>>> mip.install("github:mcauser/micropython-am2320/examples")
+```
+
+Manual installation:
+
+Copy `src/am2320.py` to the root directory of your device.
+
+
+## Examples
+
+**Basic usage**
 
 ```python
-import am2320
 from machine import I2C, Pin
-i2c = I2C(scl=Pin(5), sda=Pin(4))
+import am2320
+
+i2c = I2C(0)
 sensor = am2320.AM2320(i2c)
+
 sensor.measure()
 print(sensor.temperature())
 print(sensor.humidity())
 ```
 
-Continuous measurement
 
-```python
-import time
-import am2320
-from machine import I2C, Pin
-i2c = I2C(scl=Pin(5), sda=Pin(4))
-sensor = am2320.AM2320(i2c)
+## Methods
 
-while True:
-	sensor.measure()
-	print(sensor.temperature())
-	print(sensor.humidity())
-	time.sleep_ms(4000)
-```
+### __init__(i2c)
+
+As with other modern Aosong sensors, this sensor supports an I2C interface and can be found at address 0x5C.
+
+### check()
+
+Scans the I2C bus looking for the sensor at it's fixed I2C address 0x5C. Raises a OSError if not found.
+
+### measure()
+
+Reads the temperature and humidity from the sensor over the I2C bus and persists for subsequent calls to `temperature()` and `humidity()`.
+Received bytes contains a checksum to ensure the data is error free, otherwise an exception is raised.
+
+### temperature()
+
+Returns the temperature in degrees Celsius from the data collected from the last `measure()` call.
+
+### humidity()
+
+Get the relative humidity as a percentage from the data collected from the last `measure()` call.
+
+### _wake()
+
+The sensor goes into sleep mode when idle to help minimise influencing the readings and requires writing a byte to wake it back up.
+The write will fail, however the sensor interprets it as a wake up call.
+
+### _crc16(buf)
+
+A 16-bit cyclic redundancy check for verifying the received data is error free.
+
+
+## Parts
+
+* [AM2320](https://s.click.aliexpress.com/e/_DCcOdjL)
+* [AM2320](https://s.click.aliexpress.com/e/_DeLEjAD)
+* [TinyPICO](https://www.tinypico.com/)
+* [WeMos D1 Mini](https://www.aliexpress.com/item/32529101036.html)
+
+
+## Connections
+
+AM2320 | TinyPICO (ESP32)
+------ | ----------------
+VIN    | 3V3
+SDA    | 22
+GND    | GND
+SCL    | 21
+
+AM2320 | Wemos D1 Mini (ESP8266)
+------ | -----------------------
+VIN    | 3V3
+SDA    | GPIO4
+GND    | GND
+SCL    | GPIO5
+
+
+## Links
+
+* [micropython.org](http://micropython.org)
+* [AM2320 datasheet](docs/AM2320.pdf)
+* [TinyPICO Getting Started](https://www.tinypico.com/gettingstarted)
 
 
 ## License

am2320.py

@@ -0,0 +1,22 @@
+# SPDX-FileCopyrightText: 2016 Mike Causer <https://github.com/mcauser>
+# SPDX-License-Identifier: MIT
+
+"""
+MicroPython Aosong AM2320 I2C driver
+https://github.com/mcauser/micropython-am2320
+
+Prints the temperature and humidity
+"""
+
+from machine import I2C, Pin
+import am2320
+
+i2c = I2C(0)
+sensor = am2320.AM2320(i2c)
+
+if sensor.check():
+    print(f"AM2320 found at I2C address {am2320.I2C_ADDRESS:#x}")
+
+sensor.measure()
+print(f"Temperature: {sensor.temperature()} C")
+print(f"Humidity: {sensor.humidity()} RH")

docs/AM2320.pdf

@@ -0,0 +1,24 @@
+# SPDX-FileCopyrightText: 2016 Mike Causer <https://github.com/mcauser>
+# SPDX-License-Identifier: MIT
+
+"""
+MicroPython Aosong AM2320 I2C driver
+https://github.com/mcauser/micropython-am2320
+
+Prints the temperature and humidity every 4 sec
+"""
+
+from time import sleep_ms
+from machine import I2C, Pin
+import am2320
+
+i2c = I2C(0)
+sensor = am2320.AM2320(i2c)
+
+if sensor.check():
+    print(f"AM2320 found at I2C address {am2320.I2C_ADDRESS:#x}")
+
+while True:
+    sensor.measure()
+    print(f"Temperature: {sensor.temperature()} C, Humidity: {sensor.humidity()} RH")
+    sleep_ms(4000)

docs/demo.jpg

@@ -0,0 +1,8 @@
+{
+  "urls": [
+    ["am2320/examples/basic_measurement.py", "github:mcauser/micropython-am2320/examples/basic_measurement.py"],
+    ["am2320/examples/continuous_measurement.py", "github:mcauser/micropython-am2320/examples/continuous_measurement.py"]
+  ],
+  "deps": [],
+  "version": "1.1.0"
+}

examples/basic_measurement.py

@@ -0,0 +1,7 @@
+{
+  "urls": [
+    ["am2320/__init__.py", "github:mcauser/micropython-am2320/src/am2320.py"]
+  ],
+  "deps": [],
+  "version": "1.1.0"
+}

examples/continuous_measurement.py

@@ -0,0 +1,68 @@
+# SPDX-FileCopyrightText: 2016 Mike Causer <https://github.com/mcauser>
+# SPDX-License-Identifier: MIT
+
+"""
+MicroPython Aosong AM2320 I2C driver
+https://github.com/mcauser/micropython-am2320
+"""
+
+from time import sleep_ms
+from micropython import const
+
+__version__ = "1.1.0"
+
+I2C_ADDRESS = const(0x5C)  # fixed I2C address
+
+
+class AM2320:
+    def __init__(self, i2c):
+        self._i2c = i2c
+        self._buf = bytearray(8)
+
+    def check(self):
+        self._wake()
+        if self._i2c.scan().count(I2C_ADDRESS) == 0:
+            raise OSError(f"AM2320 not found at I2C address {I2C_ADDRESS:#x}")
+        return True
+
+    def measure(self):
+        buf = self._buf
+        # wake sensor
+        self._wake()
+        # read 4 registers starting at offset 0x00
+        self._i2c.writeto(I2C_ADDRESS, b"\x03\x00\x04")
+        # wait at least 1.5ms
+        sleep_ms(2)
+        # read data
+        self._i2c.readfrom_mem_into(I2C_ADDRESS, 0, buf)
+        crc = buf[6] | (buf[7] << 8)
+        if crc != self._crc16(buf[:-2]):
+            raise ValueError("Checksum error")
+
+    def temperature(self):
+        t = ((self._buf[4] & 0x7F) << 8 | self._buf[5]) * 0.1
+        if self._buf[4] & 0x80:
+            t = -t
+        return t
+
+    def humidity(self):
+        return (self._buf[2] << 8 | self._buf[3]) * 0.1
+
+    def _wake(self):
+        try:
+            self._i2c.writeto(I2C_ADDRESS, b"")
+        except OSError:
+            pass
+        sleep_ms(10)
+
+    def _crc16(self, buf):
+        crc = 0xFFFF
+        for c in buf:
+            crc ^= c
+            for _ in range(8):
+                if crc & 0x01:
+                    crc >>= 1
+                    crc ^= 0xA001
+                else:
+                    crc >>= 1
+        return crc