SonarMote is a project that was designed to allow reading of distances and take action either through sound (piezo buzzer), RGB LED, OLED display or through wireless. It accepts a Moteino as the microcontroller and optionally wireless transceiver and uses the HC-SR04 ultrasonic distance sensor to measure distances up to 2 meters. The HC-SR04 sensor requires 5V hence SonarMote has a 5V booster with enable function (on D5) to cut power to the sensor when not in use and so to make it battery friendly for long wireless operation.
It is meant to be powered via LiPo battery and includes an onboard charger which charges the LiPo when USB is plugged in. The Moteino is programmable via the USB as well (enumerates as FTDI serial port).

Some example projecs are (see below for some implementations):

  • parking aid with visual RGB LED indicator
  • sump pump or liquid container level monitor
  • inventory monitor/counter
  • distance tracker
  • object presence detector

Sample sketches have been posted here.

Straighten the HC-SR04 header:
A few example SonarMotes implemented as a Parking Aid (left) and a wireless sump pump water level monitor (right):

3D printable enclosure

Forum user MojaveTom has kindly shared a custom 3D printable enclosure. This would allow changing its size to fit larger batteries. Check it out on Thingiverse.