webble-idiot is a Web Bluetooth experiment hosted on GitHub Pages and based on the Google Chrome Samples.
This Web Application intends to implement the Wi-Fi Scan and Connect Services as defined in the Atmel ATWINC3400 User Guide.
By "intends", it means the document suffers from a lack of specifications.
Note: webble-idiot is tested against the Wi-Fi Scan and Connect Services implemented in the sample peripheral_wifi from the Zephyr's module esperimentative-idiot.
The document says the following for the services:
3 Scan Service Declaration
The Wi-Fi Scan Service shall be instantiated as a «Primary Service»
The service UUID shall be set to «Wi-Fi Scan Service». The UUID value assigned to «Wi-Fi Scan Service» is ‘fb8c0001-d224-11e4-85a1-0002a5d5c51b’
And:
5 Connect Service Declaration
The Wi-Fi Connect Service shall be instantiated as a «Primary Service».
The service UUID shall be set to «Wi-Fi Connect Service». The UUID value assigned to «Wi-Fi Connect Service» is ‘77880001-d229-11e4-8689-0002a5d5c51b’.
But, the document does not mention the UUID values for their corresponding characteristics.
It was assumed the characteristics UUIDs follows their services UUIDs, by incrementing by one the second 16 bits of the UUIDs (i.e. the Bytes 2 and 3).
- Service:
xxxx0001-xxxx-xxxx-xxxx-xxxxxxxxxxxx - Characteristic 1:
xxxx0002-xxxx-xxxx-xxxx-xxxxxxxxxxxx - Characteristic 2:
xxxx0003-xxxx-xxxx-xxxx-xxxxxxxxxxxx - ...
As a consequence, the tables at section 4 and 6 are amended to include the characteristic's UUID.
| Characteristics name | Requirement | Mandatory properties | Optional properties | Security | Characteristics UUID |
|---|---|---|---|---|---|
| Scanning Mode | Mandatory | Read, Write, Notify | None | fb8c0002-d224-11e4-85a1-0002a5d5c51b | |
| AP Count | Mandatory | Read | None | fb8c0003-d224-11e4-85a1-0002a5d5c51b | |
| AP Details | Mandatory | Read | None | fb8c0004-d224-11e4-85a1-0002a5d5c51b |
| Characteristics name | Requirement | Mandatory properties | Optional properties | Security | Characteristics UUID |
|---|---|---|---|---|---|
| Connection state | Mandatory | Read, Write, Notify | None | 77880002-d229-11e4-8689-0002a5d5c51b | |
| AP parameters | Mandatory | Read | Encrypted link | 77880003-d229-11e4-8689-0002a5d5c51b |
Additionally, the document says:
4.2.1 Characteristic Behavior
The AP Count characteristic consists of a single value in the range 0-15, which is the number of consecutive entries in the AP Details characteristic (starting from entry 0) that are currently valid and populated.
And defines the AP Details as follow:
4.3.1 Characteristic Behavior
The AP Details characteristic consist of a list of information, which describes the scan result for a single Wi-Fi access point. The following table describes the data structure used and the byte order transmitted.
| Field | Length | Meaning | Byte order and alignment |
|---|---|---|---|
| State | 1 | Current state of AP details entry: 0 = No details 1 = Stale details 2 = Current details | n/a |
| Channel | 1 | Wi-Fi channel number | n/a |
| Freq. band | 1 | Frequency band: 0 = 2.4GHz 1 = 5GHz | n/a |
| RSSI | 1 | Received signal strength indication in dB | n/a |
| SSID Length | 1 | Number of UINT8 elements in SSID field | n/a |
| SSID | Up to 32 | The SSID of the AP detected | The first UINT8 of the SSID is transmitted first |
The document does not say much if the AP Details characteristic sends the whole data structure for a single entry (i.e. 37 Bytes) or if it sends the very bare minimum if the SSID is less than 32 Bytes long (i.e. 5 Bytes length of SSID).
However, the total size of the full list of AP Details (16 * 37 Bytes = 592 Bytes) exeeds the limit of 512 Bytes of a characteristic value.
Therefore, the AP Count characteristic is limited to range 0..13, and the AP Details characteristic list is limited to 13 entries.
As a consequence, the section 4.2.1 is amended to reflect the range for the AP Count characteristic's UUID.
4.2.1 Characteristic Behavior
The AP Count characteristic consists of a single value in the range 0-13, which is the number of consecutive entries in the AP Details characteristic (starting from entry 0) that are currently valid and populated.
This is the TODO list for the current WIP:
- Wi-Fi Scan Service
- Read Scanning Mode
- Write Scanning Mode
- Notify Scanning Mode
- Read AP Count
- Read AP Details
- Wi-Fi Connect service
- Read Connection State
- Write Connection State
- Notify Connection State
- Read AP Parameters
- Write AP Parameters
- Make a very simple form for the user
- Split index.html into HTML and JavaScript pieces