How to sleep Arduino Nano BLE 33…

Arduino Nano BLE 33… (sense or nonsense :-) ) is based on mBed stack and it is not compatible with some Arduino standard library.

One of these is the sleep library (avr/sleep.h and avr/power.h ).

In order to put to sleep the Nano BLE, reducing current to 1mA at maximum, you can use mBed (NRF) register directly.

Here is an example:

void setup() {
 
 pinMode(2, INPUT_PULLUP);
 attachInterrupt(2,interrupt,FALLING);
pinMode(LED_BUILTIN,OUTPUT);
}
void loop() {
 digitalWrite(LED_BUILTIN, HIGH);
 delay(10000);
 digitalWrite(LED_BUILTIN, LOW);
 go_to_sleep();
}
void go_to_sleep(){
 pinMode(PIN_ENABLE_SENSORS_3V3, OUTPUT);
 pinMode(PIN_ENABLE_I2C_PULLUP, OUTPUT);
 digitalWrite(PIN_ENABLE_SENSORS_3V3, LOW); // turn off sensors
 digitalWrite(PIN_ENABLE_I2C_PULLUP, LOW);
 NRF_POWER->SYSTEMOFF = 1; 
}
void interrupt(){
 
}

The function go_to_sleep() put the microcontroller in sleeping condition. It wakes up when the button on pin 2 (which is configured ad interrupt on the falling edge) is pressed.

You can configure the button on pin 2 as turnoff/on for the entire system.

Please consider that BLE can be automatically disconnected when you put the system on sleep mode.