Sensor Protocol for Eddystone-URL

This specification is designed to offer simple and flexible way to broadcast different type of sensor values in an Eddystone-URL frame. One possible usage scenario would be:

RuuviTag sensor beacon broadcasts an encoded URL address in an Eddystone-URL frame: http://ruu.vi#53WG3vW. Once user visits the link, ruu.vi website decodes the value 53WG3vW and shows the data in a human-readable format.

The data part of the URL can be encoded in firmware of the beacon. The most powerful way to encode the data would be Base94 because the URL field of the Eddystone-URL has a support for 94 different characters. Normally it's mandatory to encode the data because of maximum length (18 characters) of the Eddystone-URL frame's URL field. We are using Base91 which has an ~equivalent efficiency.

Protocol Specification (Data Format 1)

The decoded data is a list of decimal (1-9) characters. First number defines what kind of data the field contains.

Offset	Allowed values	Description
0	0-9	Data format definition (1 = current sensor readings)
1	0-9	Temperature (1st decimal)
2	0-9	Temperature (2nd decimal)
3	0-9	Temperature (3rd decimal)
4	0-9	Humidity (1st decimal)
5	0-9	Humidity (2nd decimal)
6	0-9	Humidity (3rd decimal)
7	0-9	Atmospheric pressure (1st decimal)
8	0-9	Atmospheric pressure (2nd decimal)
9	0-9	Atmospheric pressure (3rd decimal)
10	0-9	Atmospheric pressure (4th decimal)
11	0-9	Atmospheric pressure (5th decimal)
12	0-9	Time format (0=sec, 1=min, 2=hours, 3=days)
13	0-9	Time elapsed after last movement (1st decimal)
14	0-9	Time elapsed after last movement (2nd decimal)
15	0-9	Time elapsed after last movement (3rd decimal)

Temperature

Values supported: -30°C to +69.9°C in 0.1°C increments. ####Example

Value	Measurement
000	-30°C
550	+25°C
999	+69.9°C

Humidity

Values supported: 0.0% to 99.9% in 0.1% increments. ####Example

Value	Measurement
000	0%
350	35.5%
999	99.9%

Atmospheric Pressure

Values supported: 10000Pa to 109999Pa in 1Pa increments. ####Example

Value	Measurement
00000	10000Pa
91325	101325Pa (average sea-level pressure)
99999	109999Pa

Time elapsed after last movement

Values supported: 0 sec to 999 days in sec/min/hour/day increments. ####Example

Value	Measurement
0000	0 secondes
0573	573 seconds
1141	141 minutes
2038	38 hours
3146	146 days

Data Format Decimal (Offset 0)

The first decimal is the most important one because it tells the receiver (ie. website) what kind of type of data the URL has. Only the first one (1) is implemented so far.

Decimal	Description
1	Current sensor readings
2	Reserved for future use
3	Reserved for future use
4	Reserved for future use
5	Reserved for future use
6	Reserved for future use
7	Reserved for future use
8	Reserved for future use
9	Reserved for future use