I love to tinker and write about electronics. My days are spent building projects and working as a Technical Editor for MAKE. View more articles by David Scheltema Cellular Sensor Sentinel System Diagram Expanding the capabilities of your Arduino is easily done by adding a shield. Plugging directly into an Arduino and typically including custom libraries for easy coding, sheilds provide a quick wa
![Arduino Based Cellular Sensor Sentinel](https://cdn-ak-scissors.b.st-hatena.com/image/square/28ad988efe308450526ec4a20b30302bb7e32735/height=288;version=1;width=512/https%3A%2F%2Fi0.wp.com%2Fmakezine.com%2Fwp-content%2Fuploads%2F2013%2F08%2Fgprs_system_diagram.png%3Ffit%3D3928%252C2224%26ssl%3D1)