New version available

The v2 board has improved echo handling and support for 3.3v controllers This original type is now reduced to clear. Stock are units a customer exchanged for the v2 board (he needed 3.3v), so headers are pre-installed. I have retested these before returning to stock.

What is it?

This module - and the associated library - allow you to connect eight HC-SR04 ultrasonic range sensors to an Arduino using the I2C bus and one hardware interrupt pin.

Why did you make it?

I wanted more sensors on my robot to help it navigate. I'm too cheap to buy a mega board with enough pins or smarter sensors that need less pins.

What makes it special?

The library handles all the timing, and the hardware interrupts provide surprisingly high accuracy. Each unit is individually tested using an Arduino shield based test-bed and ships with separate pin headers.

Notes:

• I missed one of the silk-screen layers which identified which port is which. Please refer to the documentation.
• If you don't use all the ports, jumper the unused Echo pins to the adjacent ground pin. This stops the inputs floating as there are no pull-down resistors on these.
• address is set to 0x3D. This can be changed via solder jumpers on the back.
• beware dodgy HC-SR04 sensors - they are not all the same. There is a particular version out there which will lock the echo pin high if it does not receive a clean Echo. As the Octosonar uses a logic gate to multiplex the Echo signal, one locked sensor will lock the whole board. See this thread on the Arduino forum
• this a 5V board. It will not operate at 3.3V, nor will it interact usefully with 3.3V controllers. Output is 5V and may damage input pins on 3.3V controllers. Coffee in cup is hot and may cause burns.

I am stocking some of the sensors and cables too, so you can get them at the same time. These are batch tested to verify that they are not the type with the echo-lock problem.

Please check out the Hackaday documentation and the github library for more info.