5.3.4.2 Request Connection Parameter Update (T,<hex16>…)

Format: T,<hex16>,<hex16>,<hex16>,<hex16>[,<hex16>]

Use command T to change the following connection parameters:
  • Interval
  • Latency
  • Supervision timeout for current connection
The connection handle received for each connection is appended as the fifth parameter to indicate the target device for multiple links. The parameters of command T are lost after reboot or power cycle. All parameters are 16-bit values in hex format. Command T is only effective if an active connection exists when the command is issued.

For more details about the ST command, definitions, ranges and relationships of the connection interval, latency and timeout, refer to Set Central Initial Connection Parameter (ST,<hex16>…) . For more details on connection parameters, see Table 5-18.

When command T with valid parameters is issued by the peripheral device, the minimum interval of timeout is required between two connection parameter update requests. The decision on whether to accept the connection parameter update request is up to the central device. When the RNBD350 module acts as a central device, it accepts all valid connection parameter update requests.

The connection parameters need to adhere to the following rules:
  • Latency <= 30
  • Maximum Interval *1.25 ms*(1+ Latency) <= 4 seconds. (4 seconds = 4000 ms)
  • Maximum Interval *1.25 ms*(1+ Latency) * 5 < Time-out * 10 ms
DefaultInterval: 0020; Latency: 0000; Timeout: 0200 ms
Example:T,0024,0024,0001,00C8// Request Connection Parameter to use interval 45 ms, latency 1, timeout 2000 ms
T,0024,0024,0001,00C8,0071// Request Connection Parameter to use interval 45 ms, latency 1, timeout 2000 ms and optional assigned connection handle 0071
Response:AOK// Success
Err// Syntax error or invalid parameter
%ERR_CONNPARM,0071%// Status string , connection handle 0071
Note: Apple® iOS® devices have some special requirements for these parameters. The connection parameter update may be rejected if it does not comply with the rules. For more information, refer to the Accessory Design Guidelines on the Apple developer website.