Hi @Seeed_Seraphina,
Where do you see that the DTH22 doesn’t use i2c? On its page in the Seeed store it lists i2c as its output signal (see table under Product Details near top of page).
I would like to get it to work over i2c too but so far, my results are consistent with “no i2c”. As you suggested, I am able to get it to work off a data pin like D2 or D4. The Adafruit library (Grove_Temperature_And_Humidity_Sensor.h) that the the OP references also doesn’t appear to use i2c. So I’m wondering if the product page is wrong. Several companies package the DHT22 sensor on their own PCB and whether or not i2c is supported is a function of the PCB itself, not the chip. Since Seeed lists i2c on the Grove implementation of this sensor and PCB, I assumed it was supported.
thanks…