Book Image

Python for Secret Agents - Volume II - Second Edition

By : Steven F. Lott
Book Image

Python for Secret Agents - Volume II - Second Edition

By: Steven F. Lott

Overview of this book

Python is easy to learn and extensible programming language that allows any manner of secret agent to work with a variety of data. Agents from beginners to seasoned veterans will benefit from Python's simplicity and sophistication. The standard library provides numerous packages that move beyond simple beginner missions. The Python ecosystem of related packages and libraries supports deep information processing. This book will guide you through the process of upgrading your Python-based toolset for intelligence gathering, analysis, and communication. You'll explore the ways Python is used to analyze web logs to discover the trails of activities that can be found in web and database servers. We'll also look at how we can use Python to discover details of the social network by looking at the data available from social networking websites. Finally, you'll see how to extract history from PDF files, which opens up new sources of data, and you’ll learn about the ways you can gather data using an Arduino-based sensor device.
Table of Contents (7 chapters)
6
Index

Simple Arduino sensor data feed


A button is not the simplest kind of sensor to read. While the concept is simple, there's an interesting subtlety to reading a button. The problem is that buttons bounce: they make some intermittent contact before they make a final, solid connection.

There's a simplistic way to debounce that involves a Busy Waiting design. We'll avoid this and show a somewhat more sophisticated debounce algorithm. As with the LED blinking, we'll rely on the millis() function to see how long the button has stayed in a given state.

To debounce, we'll need to save the current state of the button. When the button is pressed, the signal on the input pin will become HIGH and we can save the time at which this leading edge event occurred. When the button is released, the signal will go back to LOW. We can subtract the two times to compute the duration. We can use this to determine if this was a proper press, just a bounce, or even a long press-and-hold event.

The function looks like...