OSError: [Errno 5] EIO - Githubissues

rkappel commented 1 year ago

Hello,

I tried to use your library to read a DHT20 sensor and did just basically copy/paste everything using Thonny.

When running the sample code I get the error below. A simple LED blink test program works, though.

Many Thanks for your help in advance.

René

Traceback (most recent call last): File "", line 11, in File "dht20.py", line 18, in init File "dht20.py", line 28, in is_ready OSError: [Errno 5] EIO

flrrth commented 1 year ago

Hi, this could be caused by a poor connection somewhere in your breadboard. Rewiring your entire circuit could solve it.

Pokinatcha commented 1 year ago

https://github.com/flrrth/pico-dht20/blob/90540b7d3164d757746b944ff0f05ffb6c5d9a6b/dht20/dht20.py#L25-L29

Hi, change the comparison in the return of is_ready to: return self._i2c.readfrom(self._address, 1)[0] & 0x18 == 0x18

and it should work. But there are several flaws in this library. According to the datasheet, the waiting time after triggering a measurement (0xAC) must be at least 80ms, not 50ms as here. The initialization sequence of the calibration (0x1B, 0x1C, 0x1E) differs from the reference implementation of the manufacturer ASAIR.

rkappel commented 1 year ago

Hi,

I soldered the connections properly and now it works fine. I did not need to change the code in the library.

Many Thanks for your prompt response and the follow-up.

Best Regards, René

fxschmidt commented 1 year ago

Hi, I get the same error as Rene, but my wiring was okay. For me the solution was to substitute I2C(...) with SoftI2C(...). I found this solution in the MicroPython forum. Therefore my code to run the measurements is:

from machine import Pin, SoftI2C
from utime import sleep

from dht20 import DHT20

i2c0_sda = Pin(4)
i2c0_scl = Pin(5)
i2c0 = SoftI2C( sda=i2c0_sda, scl=i2c0_scl)
sleep(0.2)

dht20 = DHT20(0x38, i2c0)

while True:
    measurements = dht20.measurements
    print(f"Temperature: {measurements['t']} °C, humidity: {measurements['rh']} %RH")
    sleep(1)

I also added theses two additional lines in the dht20.py file:

# https://github.com/flrrth/pico-dht20

from machine import I2C
from utime import sleep_ms

class DHT20:
    """Class for the DHT20 Temperature and Humidity Sensor.

    The datasheet can be found at http://www.aosong.com/userfiles/files/media/Data%20Sheet%20DHT20%20%20A1.pdf
    """

    def __init__(self, address: int, i2c: I2C):
        self._address = address
        self._i2c = i2c
        sleep_ms(100)

        # Added Columns
        self._i2c.writeto(0x38, bytearray(b'\x71'))
        sleep_ms(200)

flrrth / pico-dht20

OSError: [Errno 5] EIO #3