Litter Box

This is code for an alternate main board for a litter robot 3.

Features

Current Working Features

• Clean litter box on cat detection (if CAT sensor is used).
• Clean litter box a set duration after last cycle. This is useful for cats too lite to trigger the box. It is also useful if the CAT sensor is not used.
• Empty litter box.
• Send email (or text message) on after a set number of cycles.
• Web based UI.

Litter Robot 3 Features not implemented

• Physical buttons
• Pinch detection
• Bin full detection

Hardware Needed

• ESP32s2 mini (https://amzn.to/3Ox8Swh)
• L298N motor controller (used to drive motor and provide 5V voltage step down)(https://amzn.to/3UtnYqj)
• One 2.2K resistor for the CAT detector (https://amzn.to/4889Zt4)
• Two 10K resistors for the hall effect sensors (https://amzn.to/4889Zt4)
• A Litter Robot 3 with a bad main board.

Prepare the esp32s2 mini.

Find the connection for board

Run ls /dev/tty* with the board unplugged and again with it plugged in. Find the path to the added device and set it to DEVICE_CONNECTION, example:

export DEVICE_CONNECTION=/dev/ttyACM1

Download the firmware

curl -o micropython.bin https://micropython.org/resources/firmware/LOLIN_S2_MINI-20231005-v1.21.0.bin 

Flash micropython onto the board

Make S2 boards into Device Firmware Upgrade (DFU) mode.

• Hold on Button 0
• Press Button Reset
• Release Button 0 When you hear the prompt tone on usb reconnection

esptool.py --chip esp32s2 --port $DEVICE_CONNECTION erase_flash
esptool.py --chip esp32s2 --port $DEVICE_CONNECTION write_flash -z 0x1000 micropython.bin

Customize the software (optional)

Configure web connection

In the src/wifi directory copy default_secrets.py to secrets.py and enter values for your network connection. If base_url is none the devices ip address will be used directly.

Configure alerts

Alerts require a web connection. In the src/alert directory copy default_secrets.py to secrets.py and enter values for your email.

Upload the software

Load the contents of the src directory to the board.

Wire it up

Run it

It should start running one the code is uploaded.

Logs can be read via

picocom $DEVICE_CONNECTION -b115200

Note: If it is rotating in the wrong direction you can set rotate_direction_reversed to true.

The UI

If you set up a web connection, you can access the ui via a web browser. It should look something like:

with settings something like:

• Sensitivity: adjusts the threshold used to determine if there is a cat in the box. Smaller value will trigger with less wieght in the box.
• Alert Cycles: adjusts how many cycles happen before alerts are sent on each subsuquent cycle.
• Timed Cycle Delay: adjusts how long to go without a cat detection before cycling anyway. This is useful when you have a broken cat sensor or a cat that is too light to set off the sensor.

The API

• PATCH /settings
  • Nearly all the settings are settable by sending a json object to this endpoint with the setting name and value.

Settings

The following are a list of configurable setting along with their default value.

Wifi

• wifi_connection_retries = 3
• wifi_connection_backoff = 60
• wifi_ssid
• wifi_password
• wifi_ip_config
• base_url

Litter Box

• cycle_start_ignore_hall_sensor_time = 5
• cycle_wait_time = 30
• cycle_eating_time = 7
• cycle_overshoot_time = 7
• empty_overshoot_time = 5
• empty_eating_time = 7
• hall_pin1 = 37
• hall_pin2 = 39
• load_sensor_pin = 16
• load_sensor_threshold = 3000
• l298n_ena = 18
• l298n_in1 = 33
• l298n_in2 = 35
• loop_sleep = 0.1
• rotate_direction_reversed = False
• timed_cycle_delay_hours = 24

Alert

• bin_full_cycles = 20
• smtp_server
• smtp_port
• smtp_email
• smtp_password
• bin_full_recipients