The OctoSonar 2.1 is an improved version of the popular OctoSonar, which allows you to drive 8 inexpensive HC-SR04 ultrasonic sensors from the I2C bus and one additional pin on your Arduino.

Improvements include:

• Redesigned echo signal handling, eliminating interference from misbehaving sensors.
• Address pull-down resistors and larger address jumpers
• Compatible with 5V and 3.3V controllers.

Check it out at my Tindie Store