Auriol 4-LD5380

IAN 341189_1910

433 MHz signal Pulse times are measured from rising edge to rising edge. High state of each pulse lasts about 500 µseconds. Sync pulse is ~4500 µseconds. Zero is ~1500 µseconds. One is ~2500 µseconds. Data burst consists of data packet repeated 9 times. Note: the first data packet is missing the sync pulse. Data packet construction: Sync + 36 bits

S rrrrrrrr b m id tttttttttttt ffff hhhhhhhh

	S  sync pulse (missing from the first packet)
0..7	r  random id (changes every reboot)
8	b  battery (1 = ok, 0 = low)
9	m  manual tx (1 if manual)
10..11	id numeric id 0..3 (only 0..2 normally used (*))
12..23	t  temperature (signed binary, 0.1 ℃ resolution)
24..27	f  filler bytes (1111)
28..35	h  humidity (binary)

Id, temperature and relative hudity are all sent most significant bit first. The easiest way to convert temperature into signed (16-bit) integer is if (temperature & 0x0800) { temperature |= 0xf000; } See 4-ld5380.sr for an example (sigrok data). Device ID change can be done without rebooting the sensor. Sensors seem to send data ~once per minute at 25 ℃, more seldom at lower temperatures. This may be temperature-related. Auriol receiver seems to update sensor data only once per hour or so. Sensors work with the LCD disconnected, which can be done to reduce power consumption slightly. There is no checksum, the best you can do is to majority vote among duplicate packets in burst and reject bursts with no clear winner. (*) Transmitter can be hacked into using id 3 by connecting pins 2 and 3 of the id switch. After that position "1" sends id 0, and both positions "2" and "3" send id 3. This change will make the sensor unit unusable with the original receiver unless the switch is in "1" position. For an unknown reason (multiplexing of input pins?) it also renders "tx" and "℃/F" buttons unusable regardless of id selection switch position.