Combining Sensors and Recording

Combining Sensors and Recording#

We can now combine different sensors to take multiple readings. It would be useful to also save/log multiple readings.

In this section we will cover how

Combining with SD cards#

We will take the code we developed to measure both VOCs and temperature and humidity and record those values to a SD card.

We will assume you have followed the guide on how to wire up a SD card

import board
import busio
import sdcardio
import storage
import time
import microcontroller
import digitalio
#Add imports for your sensor(s)

spi = busio.SPI(board.GP2, MOSI = board.GP3, MISO = board.GP4)   #Assign the SPI pins
cs = board.GP0
led = digitalio.DigitalInOut(board.LED)
led.direction = digitalio.Direction.OUTPUT

sdcard = sdcardio.SDCard(spi, cs)   #Create an object for the SD card
vfs = storage.VfsFat(sdcard)        #Create an object for the SD card's filesystem
storage.mount(vfs, "/sd")           #Represent the filesystem with an "sd" folder

filepath = "/sd/temperature.txt"    #Create a variable to hold the filepath

with open(filepath, "a") as f:
    f.write('Starting new set of measurements\n')
    f.write('')
print('Writing to SD card\n')

#Add set up code for your sensors

while True:
    try:
        #Acquire code goes here
        with open(filepath, "a") as f:
            f.write(f"Results: {Results}\n")
            print(f"Results: {Results}\n")
    except OSError as e:
        led.value = False
        time.sleep(0.5)
        led.value = True
        print(e)
    time.sleep(5)

Here we have taken the existing SD code and added comments where the sensor codes need to be added

import board
import busio
import sdcardio
import storage
import time
import microcontroller
import digitalio

#Add imports for your sensor(s)
import adafruit_dht
import adafruit_sgp30


spi = busio.SPI(board.GP2, MOSI = board.GP3, MISO = board.GP4)   #Assign the SPI pins
cs = board.GP0
led = digitalio.DigitalInOut(board.LED)
led.direction = digitalio.Direction.OUTPUT

sdcard = sdcardio.SDCard(spi, cs)   #Create an object for the SD card
vfs = storage.VfsFat(sdcard)        #Create an object for the SD card's filesystem
storage.mount(vfs, "/sd")           #Represent the filesystem with an "sd" folder

filepath = "/sd/temperature.txt"    #Create a variable to hold the filepath

with open(filepath, "a") as f:
    f.write('Starting new set of measurements\n')
    f.write('')
print('Writing to SD card\n')

#Add set up code for your sensors
# Set up DHT connection
dht = adafruit_dht.DHT11(board.GP0)

#Set up the SPG30 connection
i2c = busio.I2C(board.GP21, board.GP20, frequency=100000)
sgp30 = adafruit_sgp30.Adafruit_SGP30(i2c)

sgp30.iaq_init()

elapsed_sec = 0
while True:
    try:
        # Get the temp and humidity
        temp = dht.temperature
        humidity = dht.humidity
        # Now get the VOC concentration
        eCO2 = sgp30.eCO2
        TVOC = sgp30.TVOC
        with open(filepath, "a") as f:
            #Acquire code goes here
            f.write(f"({TVOC},{temp},{humidity})")
            print(f"({TVOC},{temp},{humidity})")
    except OSError as e:
        led.value = False
        time.sleep(0.5)
        led.value = True
        print(e)
    time.sleep(5)
Contents