First working version of the Cellular ExpressLink WeatherStation

examples/python/sara_example/code.py

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+import json
+import time
+import board
+import adafruit_bme680
+import busio
+from countio import Counter, Edge
+from digitalio import DigitalInOut, Direction, Pull
+from analogio import AnalogIn
+
+from expresslink import ExpressLink
+
+time.sleep(2)
+print("WeatherStation Startup")
+
+def GetVoltage(pin):
+    return (pin.value * 3.3) / 65536
+
+# Resistor table
+resistorTable = (('N',33000), ('NNE',6570), ('NE',8200), ('ENE',891), ('E',1000), ('ESE',688), ('SE',2200),('SSE',1410),('S',3900),('SSW',3140),('SW',16000),('WSW', 14120),('W',120000),('WNW',42120),('NW',64900), ('NNW', 21880))
+
+# Compute correct Resistance
+# Top resistor 10k
+# Supply voltage is 3.3v
+# R = (v * 10000)/(3.3-v)
+
+def getDirection(pin)->str:
+    v = GetVoltage(pin)
+    r = (v * 10000.0) / (3.3 - v)
+    smallestValue = 10000000
+    direction = ""
+    for entry in resistorTable:
+        distance = abs(r - entry[1])
+        if distance < smallestValue:
+            direction = entry[0]
+            smallestValue = distance
+    return direction
+
+lastTime = 0
+oldSpeed = 0
+def getSpeed(pin:Counter)->float:
+    global lastTime, oldSpeed
+    thisTime = time.time()
+    deltaTime = thisTime - lastTime
+    if deltaTime > 10:
+        windCount = pin.count
+        pin.reset()
+        lastTime = thisTime
+        hz = windCount / deltaTime
+        oldSpeed = 2.4 * hz # km/hr
+    return oldSpeed
+
+lastTip = 0
+previousTipCount = 0
+def getRainDepth(pin:Counter)->float:
+    global lastTip, previousTipCount
+    now = time.time()
+    tips = pin.count
+    if previousTipCount != tips:
+        lastTip = now
+        previousTipCount = tips
+    else:
+        if now - lastTip > (24*3600): # if there are no tips for 24 hours,
+            pin.reset()                # reset the count
+            previousTipCount = 0
+            tips = 0
+    return tips * 0.2794 # depth in mm
+
+
+windDirection = AnalogIn(board.A0)
+
+uart = busio.UART(board.UART_TX1, board.UART_RX1, baudrate=115200, timeout=30)
+el = ExpressLink(uart, DigitalInOut(board.G5), DigitalInOut(board.G2), DigitalInOut(board.G6) )
+
+el.begin()
+
+print("ExpressLink Started")
+
+i2c = board.I2C()
+bme680 = adafruit_bme680.Adafruit_BME680_I2C(i2c,debug=False)
+
+temperature_offset=-5
+
+rain = Counter(board.D1, edge=Edge.FALL, pull=Pull.UP)
+rain.reset()
+wind = Counter(board.PWM0, edge=Edge.FALL, pull=Pull.UP)
+wind.reset()
+
+response = el.sendCommand('AT+CONF? ThingName')
+thingName = response[3:]
+response = el.sendCommand("AT+CONF Topic1=weather/sensor/" + thingName)
+
+while True:
+
+    if el.connect():
+        report = {}
+        report["temperature"] = bme680.temperature+temperature_offset
+        report["gas"] = bme680.gas
+        report["humidity"] = bme680.relative_humidity
+        report["pressure"] = bme680.pressure
+        report["wind direction"] = getDirection(windDirection) 
+        report["wind speed"] = getSpeed(wind)
+        report["rain"] = getRainDepth(rain)
+        data = json.dumps(report)
+        print("Reporting : " + data)
+        el.sendCommand("AT+SEND1 " + data)
+    else:
+        print("No connection")
+        el.begin()
+
+    time.sleep(1)

examples/python/sara_example/expresslink.py

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+import busio
+import time
+from digitalio import DigitalInOut, Direction, Pull
+
+class ExpressLink:
+    event_pin:DigitalInOut # change to be an input pin with a callback
+    powerOn_pin:DigitalInOut
+    powerCheck_pin:DigitalInOut
+    _connected:bool
+    port:serial
+
+    def __init__(self, port, event, powerOn, powerCheck):
+        self.port = port
+        self.event_pin = event
+        self.powerOn_pin = powerOn
+        self.powerCheck_pin = powerCheck
+        self.event_pin.direction = Direction.INPUT
+        self.powerCheck_pin.direction = Direction.INPUT
+        self.powerOn_pin.direction = Direction.OUTPUT
+        self.powerOn_pin.value = False
+
+    # This function relies upon the SARA_ON signal to work
+    def _powerOn(self)->bool:
+        while self.powerCheck_pin.value == True:
+            self.powerOn_pin.value = True
+            time.sleep(.50)
+        self.powerOn_pin.value = False
+        time.sleep(.1)
+        print("ExpressLink Powered")
+        return True
+
+    def _comCheck(self)->bool:
+        print("Checking Communications")
+        response = ""
+        while response.find("OK") != 0:
+            time.sleep(.5)
+            response = self.sendCommand("AT")
+        return True
+
+    def begin(self):
+        self._connected = False
+        self._powerOn()
+        self._comCheck()
+        print("ExpressLink Up")
+
+    def connect(self)->bool:
+        response = self.sendCommand("AT+CONNECT?")
+        print("connect_check : " + response)
+        code = response.find("OK 1")
+        if code == -1:
+            self._connected = False
+            response = self.sendCommand("AT+CONNECT")
+            print("connect:"+response)
+            if self.checkResponse(response) == 0:
+                self._connected = True
+        else:
+            self._connected = True
+        return self._connected
+
+    def sendCommand(self, command:str)->str:
+        command += '\n'
+        self.port.write(command.encode("utf-8"))
+        time.sleep(1)
+        response = self.port.readline()
+        if response != None:
+            return response.decode("utf-8")
+        else:
+            return ""
+
+    def checkResponse(self, response:str)->int:
+        if response.find("OK") == 0:
+            return 0
+        else:
+            if response.find("ERR") == 0:
+                return int(response[3:])
+            else:
+                return -1
+
+

examples/python/sara_example/readme.md

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+# U-Blox SARA R5 ExpressLink CircuitPython Demo
+
+# ExpressLink Configuration
+Execute manual steps in the expresslink getting started guide to get the Ublox ExpressLink connected to your AWS account.
+
+# HW Configuration
+The SARA R5 ExpressLink board must be configured to enable the power state feedback.  This signal is labeled SARA_ON on the schematic.
+On the back of the board, you must apply a solder blob to the two pads labeled SARA_ON to connect that signal to G6 on the micromod.
+
+The tipping bucket is connected to signal D1 on the right side of the expresslink board.
+The wind speed is connected to signal PWM0 on the right side of the expresslink board.
+The wind direction is connected to signal A1 on the right side of the expresslink board.
+The wind direction is also connected to 3.3v via a 10k resistor.  I was able to bridge A1 to the QWICC 3v3 pin with a surface mount resistor and a bit of wire.
+
+Attach the QWICC BME680 cable between the BME680 and the ExpressLink bkard.
+
+# SW Configuration
+Install the CircuitPython image from this location: https://circuitpython.org/board/sparkfun_micromod_rp2040/
+
+Install the BME680 CircuitPython library from this location: https://github.com/adafruit/Adafruit_CircuitPython_BME680
+The BME680 library can be simply copied into the LIB folder present on the CIRCUITPY filesystem after the CircuitPython image is installed.
+Connect a USB cable to the board and open a terminal.  115200 8N1
+copy expresslink.py and code.py into the CIRCUITPY filesystem and watch the data.
+