Data Sheet

5.2.3 Wake-Up Pin Functionality
This feature can be used to prevent to Bluetooth module from entering a sleep mode or alternatively can be used to wake it up from a
sleep mode. If the sleep modes have been enabled in the hardware configuration file (see Bluetooth Dual Mode Configuration Guide)
and UART is used to communicate with the module, then this feature must be enabled and the wake-up pin must be asserted before
sending any data or BGAPI™ commands to the module, and also kept asserted until the last byte has been transferred into the module
over the UART.
The wake-up pin functionality can only be assigned to a single GPIO, but it is still possible to assign normal GPIO interrupts to other
pins. The difference between the wake-up pin and normal GPIO interrupts is that the wake-up pin will not only generate the interrupt
which wakes the module but will also keep the module awake if it is held in the asserted state. Normal GPIO interrupts can wake the
module from any state but after the interrupt event handler completes the module will return to sleep.
There is always a delay before the module wakes up. It is possible to measure the wake-up time by measuring when flow control starts
to work. Data should not be sent before the module has woken up to prevent data loss. Monitor the RTS/CTS signal to detect when the
module has woken up. There is no special command separately to wake up the module.
Table 5.1. Power Modes with Corresponding Wakeup Delays and Current Consumption
Power Mode CPU Clocks CPU Core Radio UART
Active ON Running ON Active
Power mode 1 ON Sleep ON Active
Power mode 2 OFF Stopped ON Off
The logic flow of the power saving modes in relation to each other is shown in the figure below. It is to be noted that the processor will
not lose RAM contents regardless of the power mode used.
Figure 5.1. Power Modes in Relation to Each Other and to Active Mode
5.3 Reset
BT122 can be reset by several methods: by pulling the RESET pin low, by the internal system power-up reset functionality or by the
internal watchdog timer. The RESET pin is internally connected to a pull-up resistor. The RESET pin should be connected to a push-
button, header or test point to enable the use of the system recovery mode. On an internal reset, the RESET pin will be briefly pulled
low internally. It is recommended that an external reset source is of an open drain type.
BT122 Data Sheet
Power Control
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