# Data format 4 (URL)

Related Ruuvi Devices: RuuviTag, up to B3 hardware (superceded in 2018)

The data is packed in [Eddystone URL](https://developers.google.com/beacons/eddystone) with a base of [https://ruu.vi/#](https://ruu.vi) and 9 [URL-safe base64](https://en.wikipedia.org/wiki/Base64#URL_applications) characters. Example URL is <https://ruu.vi/#BFwaAMjlQ>. This is decoded to `0x045c1a00c8e5`

| Offset |     Allowed values     | Description                                                                                                                     |
| ------ | :--------------------: | ------------------------------------------------------------------------------------------------------------------------------- |
| 0      |            4           | Data format definition (4 = current sensor readings)                                                                            |
| 1      |       `0 ... 200`      | Humidity (one lsb is 0.5%, e.g. 128 is 64%)                                                                                     |
| 2      | `-127 ... 127, signed` | Temperature (MSB is sign, next 7 bits are decimal value)                                                                        |
| 3      |        `0 ... 0`       | Temperature (fraction, 1/100.). Not used, reads always as 0.                                                                    |
| 4 - 5  |      `0 ... 65535`     | Pressure (Most Significant Byte first, value - 50kPa). Rounded to 1 hPa accuracy.                                               |
| 6      |        `0..255`        | Random id of tag, only present in format 4. NOTE! because of the URL limitation, only 6 most significant bits will be readable. |

## Data field descriptions

## Temperature

Values supported: -127.99 °C to +127.99 °C in 0.01 °C increments.

*Example*

| Value    | Measurement |
| -------- | ----------- |
| `0x0000` | 0 °C        |
| `0x8145` | -1.69 °C    |
| `0x0145` | +1.69 °C    |

## Humidity

Values supported: 0.0 % to 100 % in 0.5 % increments.

*Example*

| Value | Measurement |
| ----- | ----------- |
| `000` | 0%          |
| `128` | 64.0%       |
| `200` | 100.0%      |

## Atmospheric Pressure

Values supported: 50000 Pa to 115536 Pa in 1 Pa increments.

*Example*

| Value   | Measurement                            |
| ------- | -------------------------------------- |
| `00000` | 50000 Pa                               |
| `51325` | 101325 Pa (average sea-level pressure) |
| `65536` | 115536 Pa                              |

## Tag ID (only on format 4)

Contains a single random base 64 character used to identify tag.