What is connection parameters?

RE: What is connection parameters?

butch — Sat, 16 Dec 2017 14:24:19 GMT

"The peripheral generally will need to generate a connection parameters update request" In a use case where a peripheral is content with what the central dictates (peripheral doesn't care), is it possible for a central to require a negotiation? That is, what BLE events related to connection parameters MUST a peripheral respond to (to insure a connection is made), when the peripheral app is implemented without the connections module? In other words, the connection module is relatively new to the SDK, and older examples worked without it, is there any code in the older examples that must be used as substitute for the connections module? Maybe BLE_GATTS_EVT_EXCHANGE_MTU_REQUEST?

RE: What is connection parameters?

grzegorz — Wed, 20 Sep 2017 12:22:22 GMT

Slave Latency doesn't affect the performance at all. If there are data to be exchanged, they are transmitted with the rate determined by Connectio Interval. Slave Latency applies only to periods when there is no data to send.

RE: What is connection parameters?

Daliwan — Sat, 19 Aug 2017 04:53:57 GMT

" A Central will not start trying to reconnect before the timeout has passed"，I wonder if the central will try to reconnect until the timeout has passed and if there is no answer, then makes a decision that it is lost? Since there can be an accidental lose.

RE: What is connection parameters?

Victor Baron — Fri, 10 Jul 2015 10:29:23 GMT

"The central will respond with a connection interval that may or may not be in this range." Then what happens if the CI is not in the range ? How is it dealt by the Central / by the peripheral ? Thx in advance !

RE: What is connection parameters?

infant — Mon, 09 Jun 2014 18:13:24 GMT

"When the Peripheral requests an update, it supplies a maximum and a minimum wanted interval. " I think the Peripheral tells the Central the max and min connection interval , and the central will respond with a connection interval that may or may not be in this range.

But what's the real connection interval ,for example , in the project of *\nrf51822\Board\nrf6310\s120\experimental\ble_app_multilink_central? Is the Central determine the connection interval ?And how can I change the connection interval?

thx a lot!

RE: What is connection parameters?

Ole Morten — Mon, 10 Jun 2013 20:27:33 GMT

The connection parameters for a BLE connection is a set of parameters that determine when and how the Central and a Peripheral in a link transmits data. It is always the Central that actually sets the connection parameters used, but the Peripheral can send a so-called Connection Parameter Update Request, that the Central can then accept or reject.

There are basically three different parameters:

Connection interval: Determines how often the Central will ask for data from the Peripheral. When the Peripheral requests an update, it supplies a maximum and a minimum wanted interval. The connection interval must be between 7.5 ms and 4 s.
Slave latency: By setting a non-zero slave latency, the Peripheral can choose to not answer when the Central asks for data up to the slave latency number of times. However, if the Peripheral has data to send, it can choose to send data at any time. This enables a peripheral to stay sleeping for a longer time, if it doesn't have data to send, but still send data fast if needed. The text book example of such device is for example keyboard and mice, which want to be sleeping for as long as possible when there is no data to send, but still have low latency (and for the mouse: low connection interval) when needed.
Connection supervision timeout: This timeout determines the timeout from the last data exchange till a link is considered lost. A Central will not start trying to reconnect before the timeout has passed, so if you have a device which goes in and out of range often, and you need to notice when that happens, it might make sense to have a short timeout.

Depending on which platform you're working with, there can be platform specific recommendations or requirements on these. For iOS, Apple maintains a "Bluetooth Accessory Design Guidelines" document, which among other things includes rules on these parameters.

RE: What is connection parameters?

Pratyush Dave — Thu, 06 Jun 2013 14:13:52 GMT

For a BLE link the connection parameters control the fequency at which data can be exchanged between the peripheral and central once a BLE link has been established between the two. These parameters are negotiated between the central and master during link establishment. Examples of connection parameters are as follows. a. Connection Interval (CI): The central sets the CI when the BLE connection is first established between central and peripheral. The peripheral specifies interval minimum and maximum values, which are the upper and lower limits of the connection interval desired by the peripheral. Most centrals will use some default CI, and will generally ignore the max. and min. numbers specified by the peripheral. The peripheral generally will need to generate a connection parameters update request some time after the BLE connection is established, to try and change the CI that is within the range. The central will respond with a connection interval that may or may not be in this range. If the peripheral accepts the number, this will be the new CI. b. Slave latency c. Connection supervisory timeout.

The connection interval and slave latency typically affect the performance of a BLE link the most. The lower the slave latency and faster the connection interval the faster the effective data transfer rate between the peripheral and central. On the other hand this also leads to higher average current consumption in the peripheral.