This is an Arduino sketch that sends an SMS when an appliance has finished running. It uses an analog current sensor.
The code creates a web dashboard. You can use mDNS to easily access this dashboard. From any browser except on Android, navigate to laundry-monitor.local/ to see the sensor values, appliance states, and uptime.
I use this Modern Devices sensor. This sensor is unique among current sensors in that it doesn't require modifying the cord of the appliance. Traditional (split-core) current sensors must be attached to a single conductor, rather than the entire cord, or they won't work. The Modern Devices sensor sends an analog voltage between GND and VIN depending on the measured current. It seems to have relatively low noise (i.e. when the appliance is off, it returns 0).
The current sensors are very sensitive to position - you may need to fiddle around a bit to find the position that works. All you need is for the sensor to consistently be non-zero when the appliance is running. The sensor should mostly report zero when the appliance is off. There is filtering on the sensor, so small amounts of noise are OK.
I run this on an ESP32 dev board, the DOIT ESP32 Devkit v1, using the Arduino environment. It should work on any ESP32-based board. Note that ADC2 is unusable while WiFi is enabled, so you'll need to connect the sensor to ADC1.
This uses the smart input filter and Twilio ESP32 client libraries.
You'll need to provide some user-specific configuration values. Copy
constants.sample.h to constants.h (which is automatically ignored by Git,
for safety). Then fill out the following fields.
Enter the ssid and password for your wifi network.
This sketch uses Twilio to send SMS. The account_sid, auth_token, and
from_number are all available on the Twilio dashboard. You need to rent a
phone number from Twilio to be able to send SMS (the from_number).
This project can notify multiple people. Each person has a phone number and pins for input and output. The input pin is used to turn on and off notifications. The output pin drives an LED to display the notification status (on or off).
The first time you load this sketch, you'll need to program as normal:
$ pio run -t upload
You may need to specify the port using --upload-port.
After that, you can use ArduinoOTA to update the sketch over WiFi:
$ pio run -t upload --upload-port laundry-monitor.local
This can be a little flaky, so you may have to try a few times.