The BGX supports two power modes: Active Mode and Sleep Mode.
Active Mode Device Configuration
In active mode, the BGX has the following configuration:
- Bluetooth LE Radio Enabled:
- BLE Advertising Enabled
- BLE Scanning Enabled
- BLE Connection Enabled
- UART Enabled
Active Mode Current Consumption
The current drawn in active mode is determined by both the UART baud rate (ua b) and the current Bluetooth radio state.
Assuming the Bluetooth radio is idle (i.e. not advertising, scanning, or connected), the current consumption is:
ua b<= 9600 bps: ~3 uA
ua b> 9600 bps: ~3.25 mA
Sleep Mode Device Configuration
In sleep mode, the Bluetooth radio is either turned off or put into a limited mode of operations where it can advertise but not scan or maintain an active Bluetooth connection. The radio's operational mode is selected with the sleep mode variable (sy s sm)
sy s sm=
radio: The radio can advertise but cannot scan or maintain an active connection.
sy s sm=
deep: The radio is completely shut off and cannot perform any operations.
In sleep mode, the UART is still operational if its baud rate is 9600 bps or less. If it is greater than 9600 bps, the UART is not operational, and the host controller must wake the BGX before using the UART.
If UART flow control is enabled and the UART is not operational due to the device being in sleep mode, the UART will deassert its RTS pin to indicate to the host that it cannot not receive UART data.
Sleep Mode Current Consumption
When sy s sm is set to
deep, the estimated current
consumption is 3 uA.
The Wake on CTS variable (sy w c) only applies when the UART baud rate (ua b) is greater than 9600 bps. For baud rates of 9600 bps and below, the host can send the wake command across the UART to wake the device.
The Wake on CTS variable (sy w c) setting only takes
effect when the device transitions from Active Mode to sleep mode.
For example, if baud rate is
sy w c is
1, the Wake on CTS feature will be disabled
when the device enters Sleep Mode. While in sleep mode, the UART is operational,
so the user could set
ua b to 115200. At this point, the user might expect a
falling edge on CTS to wake the device from sleep. However, the device will not
wake, because there was no power state transition to force the new Wake on CTS
setting to take effect.
Power Modes Diagram
The Diagram below illustrates the power modes as well as the entry methods into each mode.