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The pins below can be used with `attachInterrupt()` on Nano 33 IoT.
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| Board PIN | Internal PIN |
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| Board PIN | Internal PIN |
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|----|----|
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| A1 | 15 |
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| A5 | 19 |
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| A7 | 21 |
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| D2 | 2 |
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| D3 | 3 |
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| D9 | 9 |
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| D10 | 10 |
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| A1 | 15 |
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| A5 | 19 |
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| A7 | 21 |
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| D2 | 2 |
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| D3 | 3 |
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| D9 | 9 |
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| D10 | 10 |
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| D11 | 11 |
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That information was extracted from [github.com/arduino/ArduinoCore-samd/blob/master/variants/nano_33_iot/variant.cpp](https://github.com/arduino/ArduinoCore-samd/blob/master/variants/nano_33_iot/variant.cpp).
@@ -44,7 +44,7 @@ According to the box, the Arduino Nano 33 IoT can be powered by the USB connecto
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See the results of the experiments below regarding the power supply and the peak current consumption per voltage.
The programs below have been used to test the power consumption of the embedded modules:
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***Sleep**: Using the watchdog to set the board to idle (see section *How to save power?* below)
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To to that, you just have to solder the VUSB jumper on the board.
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Notice that you cannot supply power to the board through this pin, it is only to have a handy 5V for your external components powered by the USB. If you don't power the board through the USB jack, you will stay with 0V on this pin.
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## How to save power with the Arduino Nano 33 IoT?
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The common way to save power with microcontroller is to go to sleep and use the watchdog to wakeup. Indeed, most of the power are drain while the microcontroller is doing nothing (i.e. waiting between two sample).
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There are the recommended approaches to save power with the Arduino Nano 33 IoT:
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The very popular [Low-Power library](https://github.com/rocketscream/Low-Power) is supporting the SAMD21G but only after making some patching. A good alternative is to use the [Adafruit SleepyDog Library](https://github.com/adafruit/Adafruit_SleepyDog).
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To install the library in the Arduino IDE, go in the menu *Tools -> Manage Libraries...* In the library manager, search for `Sleepy` and install the `Adafruit SleepyDog Library` by `Adafruit`.
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The usage is quite simple:
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```
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#include <Adafruit_SleepyDog.h>
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void setup() {
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pinMode(LED_BUILTIN, OUTPUT);
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digitalWrite(LED_BUILTIN, HIGH);
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}
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void loop() {
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digitalWrite(LED_BUILTIN, LOW); // Show we're sleeping
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// Sleep
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Watchdog.sleep();
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digitalWrite(LED_BUILTIN, HIGH); // Show we're awake again
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delay(5000);
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}
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```
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When you're calling the function `Watchdog.sleep()`, the board will be idle for **16 seconds** and the consumption is going as low as **6mA when powered at 3.3V** (which is quite better than 18mA with the BareMinimum program).
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The only trick is when you want to upload a new program on your board... When the board is idle, you cannot upload a new program on it because it is not listening to the USB serial. So, never upload a program without some activities (real activities or fake activities like the `delay(5000)` above) to have the time slot to upload successfully.
- Shutdown all useless components (Wifi, IMU...) and put the microcontroller (SAMD21G) in sleep mode. This will allow you to go down to 6mA while sleeping (if powered in 3.3V). [See how to put the Arduino Nano 33 IoT on sleep](SavePowerSleeping.md).
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- Shutdown the power and wake-up based on a RTC clock. This will allow you to go down to 0mA while the power is off and wake up at a specific interval of time (every minutes, every hours...). [See how to shutdown the power of the Arduino Nano 33 IoT and wake up on specific time with the RTC](SavePowerRTC.md).
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## How to use the Wifi with the Arduino Nano 33 IoT?
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The Wifi module embedded on the Arduino Nano 33 IoT is the popular [NINA W102](https://www.u-blox.com/sites/default/files/NINA-W10_DataSheet_%28UBX-17065507%29.pdf) ESP32 based module. It provides support of Wifi 802.11 b/g/n in the 2.4 GHz band and Bluetooth v4.2 (Bluetooth BR/EDR and Bluetooth Low Energy BLE). The module is fully compatible with the [official WiFiNINA library](https://www.arduino.cc/en/Reference/WiFiNINA).
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To install the official library in the Arduino IDE, go in the menu *Tools -> Manage Libraries...* In the library manager, search for `WifiNINA` and install the `WiFiNINA` by `Arduino`.
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Useful ressources:
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*[Official documentation of the WiFiNINA library](https://www.arduino.cc/en/Reference/WiFiNINA)
@@ -124,7 +93,7 @@ Useful ressources:
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### The official Arduino LSM6DS3 library (basic usage)
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To install the official library in the Arduino IDE, go in the menu *Tools -> Manage Libraries...* In the library manager, search for `LSM6DS3` and install the `Arduino_LSM6DS3` by `Arduino`.
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The usage is described on the [official Arduino website](https://www.arduino.cc/en/Reference/ArduinoLSM6DS3).
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@@ -135,7 +104,7 @@ Simple programs are available with the library:
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### The Sparkfun LSM6DS3 library (advanced usage)
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To install the official library in the Arduino IDE, go in the menu *Tools -> Manage Libraries...* In the library manager, search for `LSM6DS3` and install the `SparkFun LSM6DS3 Breakout` by `SparkFun Electronics`.
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The usage is described on the [GitHub page of the library](https://github.com/sparkfun/SparkFun_LSM6DS3_Arduino_Library). You will notice that this library is offering advanced features like:
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* Usage through multiples instances on I2C channels and SPI.
@@ -180,12 +149,12 @@ A SERCOM can be *classic* or *alternate*. In the data sheet, the *classic* is in
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For reference, see below the table I used to select the SERCOM to assign:
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Enough of theory, go for the solution...
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Add a **hardware serial on pins 5 (RX) and 6 (TX)** of the Arduino Nano 33 IoT:
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```
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```c++
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#include<Arduino.h>
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#include"wiring_private.h"
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@@ -213,7 +182,7 @@ void loop() {
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Another example, add a **hardware serial on pins 13 (RX) and 8 (TX)** of the Arduino Nano 33 IoT:
# How to save power with the Arduino Nano 33 IoT by shutting down the power and wake up on RTC alarm?
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## How to shutdown the power of the Arduino Nano 33 IoT and wake up on specific time with the RTC clock?
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In most data capture projects, the microcontroller is spending a tremendous amount of time doing nothing (waiting or sleeping). During this sleeping time, the power is consumed and the batteries are going down. In order to keep your project alive on months/years on battery, the best is to minimize the power consumption while the sleeping cycle.
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The approach described here allows to:
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- Shutdown the all power of the circuit during the sleep cycle.
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- Wake up at pre-defined interval (every minute, every hour, every day or at a specific moment).
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- Consume only the power required for the RTC clock.
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What do you need?
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- RTC DS3231 module (I use the ChronoDot 2.1 by Macetech but any DS3231 module with the INT pin wired in OK)
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- The [library DS3231 by NothernWidget](https://github.com/NorthernWidget/DS3231)
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- 2x capacitors 0.1mF
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- 2x resistors 100KOhms
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- 1x NPN transistor (I use the BC547B)
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- 1x MOSFET N-channel (I use the STP16NF06)
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The schematics is quite simple:
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If you want to reproduce this circuit on a breadboard:
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The bevaviour is easy to understand:
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- The Arduino Nano 33 IoT is piloting the RTC clock via I2C bus to set the alarm and clear the alarm.
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- The alarm of RTC clock is piloting the NPN transistor to open the power on the MOSFET.
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- The Arduino Nano 33 IoT is powered through the MOSFET.
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- The program is running only once and go everytime through the `setup()` and `loop()` functions.
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The program below is doing:
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- Blink the buildin LED 3 times fast at the startup.
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- Set the alarm on the RTC to wake up every minute.
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- Blink the building LED 5 seconds.
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- Clear the alarm to shutdown the power.
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```c++
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// Libraries required
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#include<Wire.h>
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#include<DS3231.h>
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// Global variables
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DS3231 Clock;
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voidsetup() {
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// Wait 1 second (sometime, the wake-up is hard...)
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delay(1000);
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// Initialize LED
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pinMode(PIN_LED, OUTPUT);
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// On startup, blink 3 times fast...
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for(uint8_t i = 0; i < 3; i++) {
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digitalWrite(PIN_LED, HIGH);
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delay(100);
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digitalWrite(PIN_LED, LOW);
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delay(100);
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}
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// Start the I2C interface
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Wire.begin();
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// Alarm is not enabled! Should set alarm
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if(!Clock.checkAlarmEnabled(1))
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{
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Clock.setClockMode(false);
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// 0b1111 // each second
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// 0b1110 // Once per minute (when second matches)
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// 0b1100 // Once per hour (when minute and second matches)
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// 0b1000 // Once per day (when hour, minute and second matches)
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// 0b0000 // Once per month when date, hour, minute and second matches. Once per week if day of the week and A1Dy=true
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// Set alarm to happen every minute (change to your wanted interval)
# How to save power with the Arduino Nano 33 IoT by sleeping?
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## How to put the Arduino Nano 33 IoT on sleep?
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The common way to save power with microcontroller is to go to sleep and use the watchdog to wakeup. Indeed, most of the power are drain while the microcontroller is doing nothing (i.e. waiting between two sample). This will allow you to go down to 6mA at the microcontroller level while sleeping (if powered in 3.3V).
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+
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+
The very popular [Low-Power library](https://github.com/rocketscream/Low-Power) is supporting the SAMD21G but only after making some patching. A good alternative is to use the [Adafruit SleepyDog Library](https://github.com/adafruit/Adafruit_SleepyDog).
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+
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+
To install the library in the Arduino IDE, go in the menu *Tools -> Manage Libraries...* In the library manager, search for `Sleepy` and install the `Adafruit SleepyDog Library` by `Adafruit`.
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The usage is quite simple:
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```c++
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#include<Adafruit_SleepyDog.h>
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voidsetup() {
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pinMode(LED_BUILTIN, OUTPUT);
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digitalWrite(LED_BUILTIN, HIGH);
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}
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voidloop() {
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digitalWrite(LED_BUILTIN, LOW); // Show we're sleeping
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// Sleep
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Watchdog.sleep();
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digitalWrite(LED_BUILTIN, HIGH); // Show we're awake again
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delay(5000);
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}
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```
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When you're calling the function `Watchdog.sleep()`, the board will be idle for **16 seconds** and the consumption is going as low as **6mA when powered at 3.3V** (which is quite better than 18mA with the BareMinimum program).
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+
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+
The only trick is when you want to upload a new program on your board... When the board is idle, you cannot upload a new program on it because it is not listening to the USB serial. So, never upload a program without some activities (real activities or fake activities like the `delay(5000)` above) to have the time slot to upload successfully.
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