First of all, need to understand several states of the Bluetooth BLE device: one of the slave is in standby, broadcast, and connection state, and the master is in standby, scanning, or connection state. The connection interval is a parameter for the connection state. If two devices are not connected, this parameter will not affect the power consumption in this state.
Once again, the device is generally in the broadcast state when it is not in the connected state, reducing power consumption, and of course, it can increase the broadcast interval. The principle is that the Bluetooth device wakes up to transmit broadcast messages after a certain period (broadcast interval), the rest of the time is in sleep state, and the power consumption is 1uA (PM2 mode). The broadcast interval is increased, and the sleep time is longer, which naturally reduces Power consumption.
Therefore, parameters that affect power consumption, including ADV parameters and connection parameters, play a role in different states.
1. Broadcast interval
During the broadcast, the interval of each broadcast data transmission can also affect the power consumption of the BLE device, so the broadcast interval can be modified to be larger to reduce power consumption. However, it should be noted that if the broadcast interval is changed to a large value, the connection speed of the BLE device will be affected accordingly. Therefore, it should not be modified too much. It is best to broadcast the default 20ms connection interval.
2. Duration of the broadcast
In the broadcast mode, you can set the broadcast duration after each broadcast starts. It goes without saying that the shorter the broadcast duration, the more power saving. Of course, the specific time can be determined according to the actual use occasion.
3. Connection interval
When a Bluetooth BLE device is connected, the Bluetooth master sends a Connection Event to the BLE device. After receiving the connection event, the BLE device will reply to notify the Bluetooth master that the connection path is normal. This time is really the time when the BLE device consumes the most power, so increasing the connection interval time will reduce the power consumption of the BLE device, but it should be noted that changing the connection interval time will correspondingly change the Bluetooth communication speed. Need to be modified carefully.
4. Times of Slave delay
The so-called Slave Latency times is the number of times that connection events are ignored during the connection. In each Connection Event, the Bluetooth master must send a packet first, and then the Bluetooth device must reply. Repeat this way, otherwise the Bluetooth master will think that the Bluetooth device is abnormal. By setting the number of slave delays, the Bluetooth device is not allowed to reply to the Bluetooth master data within a certain number of times. The Bluetooth master will not consider the Bluetooth device abnormal even if it does not receive a reply from the Bluetooth device. In this case, the Bluetooth device will be reduced its power consumption.
