AVR-AM2320-Single-Wire

AM2320 temperature and humidity sensor interface for AVR ATtiny85 through Single Wire.

Uses PB3 by default.

Sensor values are stored in the byte array msg following the order they are sent by the sensor (Big Endian, that is, the most significant byte first):

• The first two bytes contain the humidity (in Big Endian)
• The second two bytes contain the temperature (also in Big Endian)
• The last byte contains the CRC

This has been tested with an ATtiny85, but should work with any other AVR microcontroller that allows 8MHz clock speed.

Function overview

init()

Called at the beginning of your program. It sets the CPU clock at 8MHz (required by the speed the sensor sends the data), sets the pull-up resistor on the PB3 pin an sets it into input mode, and enables edge interrupt for this pin.

poll()

Wakes up the sensor and stores the answer into the array tm.

parsetm()

Parses the timings stored in tm and stores the result in msg. It also checks the CRC.

Returns 1 if the CRC check is correct, else 0.