Best Phidgets Practices

The purpose of this page is to provide you with a list of "Best Practices" to follow when writing code that uses Phidgets. These guidelines are especially important if your program is going to be used by people other than you, or on many different systems. If you follow these guidelines, you'll probably save yourself a few headaches in the future.

Keep Event Handlers Short

Event handlers (specifically the ones that handle data "change" events) are constantly being put on the stack as data comes in on your typical Phidget program. The purpose of these handlers is to give you an opportunity to process each point of data that comes in. For example, you might convert a temperature reading from Celsius to Kelvin, or you might perform a rolling average on data coming in from your load cell. However, problems can arise if you try to do too much in your event handler. Actually, it has less to do with the amount of code and more to do with the type of code that's in your handler.

Imagine you have an accelerometer that's sending acceleration data every 20 milliseconds. If your change handler takes 21ms to execute, the next data point will be ready before the previous one is done being processed. Now, occasionally going over-time is not a problem, since the Phidgets drivers will queue up to 500 data points before it starts dropping (ignoring) data points. But if your handler consistently takes longer than your sensor's data interval, you're not going to be able to keep up.

You can keep the execution time of your event handlers down by avoiding the use of notoriously time-expensive tasks, or by using a separate thread to handle these aspects. Some such tasks include:

• Updating GUI elements
• Waiting for user input
• Writing to a file