【Digi-Key Follow Me Episode 3】Task 5: Using External Sensors

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【Digi-Key Follow Me Episode 3】Task 5: Using External Sensors [Copy link]

 

Ambient Light Sensor:

This is an analog sensor. It is connected to the GPIO2 interface of the core board through Grove, and uses the built-in ADC to read the voltage.

When reading from ADC, you can read the value in u16 format, or you can directly get the specific voltage value. Just call the method directly.

This ambient light sensor uses SENBA's LS06-S sensor, which is connected in series with a 68k resistor, and the intermediate output is sent to LM358. Since the output is not linear with the light intensity, the specific illumination value is not calculated here, and only qualitative analysis is done.

Place a mobile phone next to it as a brightness reference.

The read data is displayed on the screen.

code show as below

adc = ADC(Pin(2), atten=ADC.ATTN_11DB)

while True:
    light_adc = adc.read_u16()
    light_uv = adc.read_uv()
    oled.fill(0)
    oled.text(f'light_adc: {light_adc}', 0, 0)
    oled.text(f'light_mv: {light_uv / 1000}', 0, 10)
    oled.show()
    sleep(1)

The running effect is as follows. You can see that at the beginning, the brightness is high, and the numbers displayed on the phone and the display are large. When you block the light with your hand, the numbers displayed on the phone and the display become very small. After you remove your hand, the larger values are restored. The green circuit board below is only for fixing

light

Temperature and humidity sensor:

This is a digital sensor that transmits data via the I2C protocol. The chip used is AHT20, which can communicate directly via the I2C protocol according to the specifications. Due to its wide use, there is already a library written, so just call ahtx0.py here. First, you need to make sure this file has been written to the core board.

Place a thermometer and humidity meter next to it for reference.

Likewise, the read data is displayed on the display. The reading speed is limited to once every 2 seconds to prevent the reading itself from heating up.

code show as below

import ahtx0

aht20 = ahtx0.AHT20(i2c)
while True:
    t = aht20.temperature
    h = aht20.relative_humidity
    oled.fill(0)
    oled.text(f'T: {t}', 0, 0)
    oled.text(f'H: {h}', 0, 10)
    oled.show()
    sleep(2)

The operation results are as follows. It can be seen that at the beginning, the temperature and humidity are close to the temperature and humidity meter, and the reading is relatively accurate. After blocking the sensor with a finger, the humidity and temperature both rise significantly and rapidly due to the temperature and sweat of the human body.

temperature