Adafruit S-35710 Low-Power Wake Up Timer Breakout

Watchdog timing over STEMMA QT

by Liz Clark

published May 11, 2024, last edited January 22, 2025

posted in Adafruit Products Arduino Compatibles CircuitPython Breakout Boards STEMMA

Beginner

Product guide

Arduino

Using the S-35710 breakout with Arduino involves wiring up the breakout to your Arduino-compatible microcontroller, installing the Adafruit_S-35710 library, and running the provided example code.

Wiring

Wire as shown for a 5V board like an Uno. If you are using a 3V board, like an Adafruit Feather, wire the board's 3V pin to the breakout VIN.

Here is an Adafruit Metro wired up to the breakout using the STEMMA QT connector:

Board 5V to breakout VIN (red wire)
Board GND to breakout GND (black wire)
Board SCL to breakout SCL (yellow wire)
Board SDA to breakout SDA (blue wire)

Here is an Adafruit Metro wired up using a solderless breadboard:

Board 5V to breakout VIN (red wire)
Board GND to breakout GND (black wire)
Board SCL to breakout SCL (yellow wire)
Board SDA to breakout SDA (blue wire)

Library Installation

You can install the Adafruit_S-35710 library for Arduino using the Library Manager in the Arduino IDE.

Click the Manage Libraries ... menu item, search for Adafruit_S-35710, and select the Adafruit S-35710 library:

If asked about dependencies, click "Install all".

If the "Dependencies" window does not come up, then you already have the dependencies installed.

If the dependencies are already installed, you must make sure you update them through the Arduino Library Manager before loading the example!

Example Code

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#include "Adafruit_S35710.h"
#include <Wire.h>

// Optional reset pin connected to the S35710
const uint8_t RESET_PIN = -1;

// Create the S35710 with the reset pin
Adafruit_S35710 s35710 = Adafruit_S35710(RESET_PIN);

void setup() {
  // Start the serial communication
  Serial.begin(115200);
  while (!Serial)
    ; // Wait for serial port to connect

  Serial.println("Adafruit S-35710 Test!");

  if (!s35710.begin(&Wire, S35710_I2C_ADDRESS)) {
    Serial.println("Failed to initialize S-35710!");
    while (1)
      ;
  }
  Serial.println("S35710 initialized!");

  uint32_t wakeupTimeValue = 3; // 3 seconds

  Serial.print("Setting wake-up time to ");
  Serial.print(wakeupTimeValue);
  Serial.println(" seconds");
  if (!s35710.setWakeUpTimeRegister(wakeupTimeValue)) {
    Serial.println("Failed to set wake-up time register!");
    while (1)
      ;
  }

  // Test getting the wake-up time register
  int32_t readWakeupTimeValue = s35710.getWakeUpTimeRegister();
  if (readWakeupTimeValue == -1) {
    Serial.println("Failed to read wake-up time register!");
    while (1)
      ;
  }
  Serial.print("Wake-up time set to ");
  Serial.print(readWakeupTimeValue);
  Serial.println(" seconds");

  Serial.println();
}

void loop() {
  int32_t readTimeValue = s35710.getTimeRegister();
  int32_t readWakeupTimeValue = s35710.getWakeUpTimeRegister();
  if (readTimeValue == -1 || readWakeupTimeValue == -1) {
    // Hmm failed to read? wait & retry
    delay(1000);
    return;
  }

  Serial.print("Internal timer: ");
  Serial.print(readTimeValue);
  Serial.print(" s, alarm set: ");
  Serial.print(readWakeupTimeValue);
  Serial.println(" s");

  delay(1000);
}

#include "Adafruit_S35710.h"
#include <Wire.h>

// Optional reset pin connected to the S35710
const uint8_t RESET_PIN = -1;

// Create the S35710 with the reset pin
Adafruit_S35710 s35710 = Adafruit_S35710(RESET_PIN);

void setup() {
  // Start the serial communication
  Serial.begin(115200);
  while (!Serial)
    ; // Wait for serial port to connect

  Serial.println("Adafruit S-35710 Test!");

  if (!s35710.begin(&Wire, S35710_I2C_ADDRESS)) {
    Serial.println("Failed to initialize S-35710!");
    while (1)
      ;
  }
  Serial.println("S35710 initialized!");

  uint32_t wakeupTimeValue = 3; // 3 seconds

  Serial.print("Setting wake-up time to ");
  Serial.print(wakeupTimeValue);
  Serial.println(" seconds");
  if (!s35710.setWakeUpTimeRegister(wakeupTimeValue)) {
    Serial.println("Failed to set wake-up time register!");
    while (1)
      ;
  }

  // Test getting the wake-up time register
  int32_t readWakeupTimeValue = s35710.getWakeUpTimeRegister();
  if (readWakeupTimeValue == -1) {
    Serial.println("Failed to read wake-up time register!");
    while (1)
      ;
  }
  Serial.print("Wake-up time set to ");
  Serial.print(readWakeupTimeValue);
  Serial.println(" seconds");

  Serial.println();
}

void loop() {
  int32_t readTimeValue = s35710.getTimeRegister();
  int32_t readWakeupTimeValue = s35710.getWakeUpTimeRegister();
  if (readTimeValue == -1 || readWakeupTimeValue == -1) {
    // Hmm failed to read? wait & retry
    delay(1000);
    return;
  }

  Serial.print("Internal timer: ");
  Serial.print(readTimeValue);
  Serial.print(" s, alarm set: ");
  Serial.print(readWakeupTimeValue);
  Serial.println(" s");

  delay(1000);
}

View on GitHub

Upload the sketch to your board and open up the Serial Monitor (Tools -> Serial Monitor) at 115200 baud. You'll see the S-35710 recognized over I2C. Then, an alarm is set for 3 seconds. In the loop, the internal timer is printed out every second along with the alarm. Once the internal timer reaches 3 seconds, the alarm expires.