Eddystone URL Encoding : A Beginner's Guide

For beginners who need to know how to convert url into UINT8_T, This can be a very helpful information:

To begin with, beginners need to know exactly what the URL frame contains and here is the details:

The first 9 bytes of the frame are just prefix. To check the content of the prefix value, see the picture below:

The 10th and 11th byte is constant having the value "AAFE". And starting on the 12th byte is the actual eddystone frame which is broken down into the following:

Frame Specification

Byte offset	Field	Description
0	Frame Type	Value = 0x10
1	TX Power	Calibrated Tx power at 0 m
2	URL Scheme	Encoded Scheme Prefix
3+	Encoded URL	Length 1-17

The URL prefix have constant designated values:

URL Scheme Prefix

The URL Scheme Prefix byte defines the identifier scheme, an optional prefix and how the remainder of the URL is encoded.

Decimal	Hex	Expansion
0	0x00	http://www.
1	0x01	https://www.
2	0x02	http://
3	0x03	https://

The URL Expansion also have constant values:

Decimal	Hex	Expansion
0	0x00	.com/
1	0x01	.org/
2	0x02	.edu/
3	0x03	.net/
4	0x04	.info/
5	0x05	.biz/
6	0x06	.gov/
7	0x07	.com
8	0x08	.org
9	0x09	.edu
10	0x0a	.net
11	0x0b	.info
12	0x0c	.biz
13	0x0d	.gov
14..32	0x0e..0x20	Reserved for Future Use
127..255	0x7F..0xFF	Reserved for Future Use

And the remaining strings in url are converted to hex ascii codes. The URL is 17 bytes including the expansion value.

Here is the raw data from nRF Connect App:

And here is the actual raw data:

To Interpret the data

Byte offset	Field	Value
0	Frame Type	0x10
1	TX Power	0x04
2	URL Scheme	0x00 = "http://www."
3+	Encoded URL	0x06D696E65777465636807 The last 2 digits "07" is the URL extension for ".com"

0x06D696E657774656368 when converted to string is "minewtech". I used the foloowing website for the conversion:

http://www.unit-conversion.info/texttools/hexadecimal/#data

Combining the decoded data that we will get "http://www.minewtech.com"