SmartAngle: how it works

Bubble levels

Bubble levels are simple to understand, simple to use and find their own level thanks to gravity. With a bit of experience very accurate measurements can be made with the human eye.

It is worth remembering that a spirit level can be inaccurate if the vials holding the liquid are not set in place properly. Always check a level by rotationg it horizontally through 180 degrees - if the readings are exactly the same the level is accurate. High quality engineering levels allow the vials to be adjusted.

The effects of gravity are obvious (things fall down!) but measuring it can be quite hard because it isn't the same everywhere

Digital levels

Digital levels use tiny devices called "accelerometers" which can measure the force of gavity in at least three dimensions.

As their name indicates, they are extremely good at measuring acceleration, the change in motion of an object. Note: not the "speed" of an object, but its "change" in motion.

Gravity is a property of mass (bigger things exert more gravitation pull) but beyond knowing what it does we haven't a clue about what it really is - ask a scientist! Here's our way of understanding how accelerometers work.

• Image a spring suspended from a hook in the ceiling.
• Now hang a weight on the end of the spring.
• The weight will be pulled downwards, and the spring will be extended, until the force exerted by the spring exactly matches the force of gravity.
• The accelerometer measures that matching force.

Digital levels require calibrating to match the force of gravity at any point on earth. This process is done once only for any particular location.

The video below shows how SmartAngle is calibrated.

Inside SmartAngle

As well as an accelerometer, SmartAngle contains:

• A microprocessor which continously takes readings from the accelerometer.
• A Bluetooth module used to send data from the microprocessor to the DryFire app.
• A CR2032 battery.
• A membrane button used to "wake up" the microprocessors which "goes to sleep" after a period of inactivity.

  Going to sleep means the microprocessor consumes only a tiny amount of power, just enough so it can be woken up when the switch is pressed.

That's the hardware.

The really clever stuff is the firmware inside the microprocessor and the software in the app. The main task is to convert the numbers coming from the accelerometer into angles displayed on the smartphone or tablet.

Using a longer levelling base

The easiest way to extend SmartAngle's levelling base is to place it on a traditional bubble level - even better if the bubble level has a magnetic side because SmartAngle will stick to it.

We have manufactured a small run of 150mm aluminium extrusions to convert SmartAngle into a longer level. The extrusion has a small steel plate inside to which SmartAngle fits magnetically - there are also three mounting holes so that SmartAngle can be held in place permanently if preferred.