Arduino Mega and AM2305B

Other Hardware Sensors
1

For years, I've been using AM2305 sensors for one of my MEGA projects. They have been working great, and they seem to be much more reliable than the little, white DHT22 sensors. However, they have been increasingly hard to find, and the last batch I bought ended up being AM2305B sensors (not AM2305). The AM2305B are promoted as being even more reliable, but they don't seem to work as drop-in replacements. I get TEMP values that are WAY off (like 52 instead of the real 72).
Does anyone know of an updated library for these?
Or, should I be using an entirely different library?

Thanks.

2

AM2305B Product Overview:

AM2305B digital temperature and humidity sensor is a calibrated digital signal output of the temperature and humidity combined sensor. It uses a dedicated digital modules capture technology and the temperature and humidity sensor technology to ensure that products with high reliability and excellent long-term stability. Sensor includes a capacitive humidity sensing element and a DS18B20 temperature measurement devices, and with a high-performance 8-bit microcontroller connected.

3

That doesn't help at all.

4

So, it appears that I have been making an invalid assumption...

Since I started using the AM2305 sensors, I have never needed to use a pullup resistor - even when the sensor is at the end of 100' of CAT3 wire.

When I read that the AM2305B sensor is an upgraded version of the original sensor, it didn't dawn on me that I would need to add the 4.7k resistor to pull up the data line.

Well, in fact, the 4.7k resistor does appear to be necessary because the AM2305B sensor works with the resistor in place but not without it.
Silly me for making assumptions.

FYI - the "INPUT_PULLUP" setting on the MEGA pin is not enough. The internal resistance value must be too high.

I hope this helps.

5

En la hoja de datos del AM2305B, indica que se debe conectar una resistencia de 4,7 k, sin embargo funciona perfectamente sin esta. tambien es compatible con DHT22, teniendo que tener un tiempo de 2 segundos para espera entre mediciones. Quiza sea que el sensor o los sensores con los que cuenta esten defectuosos.