First working code for HC-SR04 sensor.

README.md

@@ -18,4 +18,15 @@ import upip
 upip.install('umqtt.simple')
 upip.install('umqtt.robust')
 ```
+for later versions of MicroPython, you should use `mip` instead...
+```
+import network
+wlan = network.WLAN(network.STA_IF)
+wlan.active(True)
+wlan.connect("Wi-Fi AP", "PASSWORD")
+
+import mip
+mip.install('umqtt.simple')
+mip.install('umqtt.robust')
+```
 - Upload files onto PICO, adjust params (such as Wi-Fi Credentials // pins // etc ), deploy to your PICO W 

hcsr04_funcs.py

@@ -0,0 +1,34 @@
+import time
+
+'''
+hcsr04_funcs: Helper functions to interact with the HC-SR04 sensor.
+'''
+
+def read_hc_sr04(trig, echo):
+    """
+        reads the HC-SR04 sensor.
+        returns tuple(temperature, humidity) if no errors
+        returns None if there was an error
+    """
+    try:
+        trig.value(0)
+        time.sleep(0.1)
+         
+        trig.value(1)
+        time.sleep_us(2)
+        
+        trig.value(0)
+        
+        while echo.value()==0:
+             pulse_start = time.ticks_us()
+        
+        while echo.value()==1:
+             pulse_end = time.ticks_us()
+        
+        pulse_duration = pulse_end - pulse_start
+        distance = pulse_duration * 17165 / 1000000
+        distance = round(distance, 2)
+        
+        return distance
+    except:
+        return None

main.py

@@ -1,107 +1,29 @@
+# Built-in's
 import network
 import rp2
 import time
 import json
 import machine
-from machine import Pin
+
+# From PyPI
 from umqtt.robust import MQTTClient
-import dht
+
-import urequests
+# From this project...
-import wifi_config
 import mqtt_config
+from pico_funcs import read_cpu_temp, wlan_up, led_error_code
+from hcsr04_funcs import read_hc_sr04
 
 # Change this GPIO PIN where your DHT22 sensor is connected
-DHT_22_GPIO_PIN = 3
+TRIG_PIN = 3
+ECHO_PIN = 2
 
 # Debug Mode
 DEBUG = False
-
-def read_cpu_temp():
-    """
-        If you print the value of the temperature value you are going to get an integer number between 0 and 65535.
-        So, we have to convert this value either to the Celsius degree scales.
-
-        The temperature sensor works by delivering a voltage to the ADC4 pin that is proportional to the temperature.
-        From the datasheet, a temperature of 27 degrees Celsius delivers a voltage of 0.706 V.
-        With each additional degree the voltage reduces by 1.721 mV or 0.001721 V.
-        The first step in converting the 16-bit temperature is to convert it back to volts, which is done based on the 3.3 V maximum voltage used by the Pico board.
-        ref: https://how2electronics.com/read-temperature-sensor-value-from-raspberry-pi-pico/
-    """
-    cpu_temp_conversion_factor = 3.3 / 65535
-    cpu_temp_sensor = machine.ADC(4)
-    reading = cpu_temp_sensor.read_u16() * cpu_temp_conversion_factor
-    temperature_c = 27 - (reading - 0.706) / 0.001721
-    temperature_f = temperature_c * 9/5. + 32.0
-    return temperature_f
-
-def read_dht_22(sensor):
-    """
-        reads the temperature and humidity from dht.DHT22 sensor.
-        returns tuple(temperature, humidity) if no errors
-        returns None if there was an error
-    """
-    try:
-        sensor.measure()
-        temperature = sensor.temperature()
-        humidity = sensor.humidity()
-        return temperature, humidity
-    except:
-        time.sleep(2)
-        return None
-
-def wlan_up(wlan):
-    wlan.active(True)
-    wlan.connect(wifi_config.HOME_WIFI_SSID, wifi_config.HOME_WIFI_PWD)
-    
-    # Wait for connect or fail
-    max_wait = 10
-    while max_wait > 0:
-        if wlan.status() < 0 or wlan.status() >= 3:
-            break
-        max_wait -= 1
-        if DEBUG:
-            print('Waiting for WiFi connection...')
-        time.sleep(1)
-
-    if max_wait == 0:
-        return None
-    
-    ifconfig = wlan.ifconfig()
-    if DEBUG:
-        print(ifconfig)
-    return ifconfig
-    
-def led_error_code(led, error_code: int):
-    """Blink LED for a given error code (int). error code == number of times to blink"""
-    if DEBUG:
-        print("LED Error Status code: {}".format(error_code))
-    
-    # Run a quick 'start error code sequence'
-    # So we know when LED error sequence starts
-    start_sequence_counter = 0
-    while start_sequence_counter < 3:
-        led.value(True)
-        time.sleep(0.1)
-        led.value(False)
-        time.sleep(0.1)
-        start_sequence_counter += 1
-    
-    # Run real error code sequence
-    blink_counter = 0
-    while blink_counter < error_code:
-        time.sleep(1)
-        led.value(True)
-        time.sleep(1)
-        led.value(False)
-        blink_counter += 1
-    # Make sure to turn off LED when this subroutine finished
-    led.value(False)
-    if DEBUG:
-        print("LED Error Status code finished for: {}".format(error_code))
-    
     
 def main():
 
+
+
     # Start Up Activities
     if DEBUG:
         print("Start up")
@@ -110,7 +32,7 @@ def main():
     led.value(False)
     led_error_code(led, 1)
 
-    # Set Wi-Fi Country
+    # Set Wi-Fi Country and Create a Wireless Interface
     rp2.country('US')
     wlan = network.WLAN(network.STA_IF)
     
@@ -120,8 +42,9 @@ def main():
         server = mqtt_config.MQTT_HOST_NAME,
         )
 
-    # Create DHT22
+    # Create HC-SR04
-    sensor = dht.DHT22(Pin(DHT_22_GPIO_PIN))
+    trig = machine.Pin(TRIG_PIN, machine.Pin.OUT)
+    echo = machine.Pin(ECHO_PIN, machine.Pin.IN, machine.Pin.PULL_DOWN)
     
     # Let's Go!
     if DEBUG:
@@ -138,20 +61,18 @@ def main():
         # Create Local Flags for Control
         wifi_ready = False
         mqtt_ready = False
-        dht22_ready = False
+        hc_sr04_ready = False
 
-        # DHT22 and CPU Reading.
+        # CPU Reading.
         try:
-            # CPU Reading.
             cpu_temp = read_cpu_temp()
+        except:
+            continue
 
-            # DHT22 Reading.
+        # HC-SR04 Reading.
-            dht22_reading = read_dht_22(sensor)
+        try:
-            #debug_str = "None"
+            distance = read_hc_sr04(trig, echo)
-            if dht22_reading is not None:
+            hc_sr04_ready = True
-                temp,hum = dht22_reading
-                temp = temp * 9/5. + 32.0
-                dht22_ready = True
         except:
             continue
 
@@ -196,18 +117,17 @@ def main():
 
         # Ready to Publish?
         try:
-            if wifi_ready and mqtt_ready and dht22_ready:
+            if wifi_ready and mqtt_ready and hc_sr04_ready:
                 # Timestamp
                 time_now = time.localtime()
                 timestamp = "{}/{}/{} {}:{}:{}".format(time_now[1],time_now[2],time_now[0],time_now[3],time_now[4],time_now[5])
                 
                 # Build JSON Payloads
-                dht_data = {
+                hc_sr04_data = {
                     'Location':mqtt_config.MQTT_ZONE_ID,
-                    'Temperature':temp,
+                    'Distance':distance,
-                    'Relative Humidity':hum,
                 }
-                dht_payload = json.dumps(dht_data)
+                hc_sr04_payload = json.dumps(hc_sr04_data)
                 
                 hw_data = {
                     'Timestamp':timestamp,
@@ -218,7 +138,7 @@ def main():
                 hw_payload = json.dumps(hw_data)
                 
                 # Publish
-                mqtt_client.publish("home/{}".format(mqtt_config.MQTT_ZONE_ID),dht_payload, retain=True)
+                mqtt_client.publish("home/{}".format(mqtt_config.MQTT_ZONE_ID),hc_sr04_payload, retain=True)
                 mqtt_client.publish("hw/{}".format(mqtt_config.MQTT_HW_ID),hw_payload, retain=True)
         
                 mqtt_client.disconnect()

pico_funcs.py

@@ -0,0 +1,68 @@
+import machine
+import network
+import wifi_config
+import time
+
+'''
+pico_funcs: Helper functions for things the pico can do.
+'''
+
+def read_cpu_temp():
+    """
+        If you print the value of the temperature value you are going to get an integer number between 0 and 65535.
+        So, we have to convert this value either to the Celsius degree scales.
+
+        The temperature sensor works by delivering a voltage to the ADC4 pin that is proportional to the temperature.
+        From the datasheet, a temperature of 27 degrees Celsius delivers a voltage of 0.706 V.
+        With each additional degree the voltage reduces by 1.721 mV or 0.001721 V.
+        The first step in converting the 16-bit temperature is to convert it back to volts, which is done based on the 3.3 V maximum voltage used by the Pico board.
+        ref: https://how2electronics.com/read-temperature-sensor-value-from-raspberry-pi-pico/
+    """
+    cpu_temp_conversion_factor = 3.3 / 65535
+    cpu_temp_sensor = machine.ADC(4)
+    reading = cpu_temp_sensor.read_u16() * cpu_temp_conversion_factor
+    temperature_c = 27 - (reading - 0.706) / 0.001721
+    temperature_f = temperature_c * 9/5. + 32.0
+    return temperature_f
+
+def wlan_up(wlan):
+    wlan.active(True)
+    wlan.connect(wifi_config.HOME_WIFI_SSID, wifi_config.HOME_WIFI_PWD)
+    
+    # Wait for connect or fail
+    max_wait = 10
+    while max_wait > 0:
+        if wlan.status() < 0 or wlan.status() >= 3:
+            break
+        max_wait -= 1
+        time.sleep(1)
+
+    if max_wait == 0:
+        return None
+    
+    ifconfig = wlan.ifconfig()
+    return ifconfig
+
+def led_error_code(led, error_code: int):
+    """Blink LED for a given error code (int). error code == number of times to blink"""
+    
+    # Run a quick 'start error code sequence'
+    # So we know when LED error sequence starts
+    start_sequence_counter = 0
+    while start_sequence_counter < 3:
+        led.value(True)
+        time.sleep(0.1)
+        led.value(False)
+        time.sleep(0.1)
+        start_sequence_counter += 1
+    
+    # Run real error code sequence
+    blink_counter = 0
+    while blink_counter < error_code:
+        time.sleep(1)
+        led.value(True)
+        time.sleep(1)
+        led.value(False)
+        blink_counter += 1
+    # Make sure to turn off LED when this subroutine finished
+    led.value(False)