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This is a simple touch sensor module. You can use it to replace a traditional push button. Using the TTP223-B touch detector IC It measures the capacitance of a metallic pad. It can detect the change in capacitance when a finger is near it. This is the same technology used in the iPhone touch screen. So you can place the metallic pad under a non-metallic surface such as a plastic or glass sheet and it will still work as a button. This may be useful for projects that need to be waterproof. You can also make a secret button by placing it inconspicuously behind a smooth surface. For instance you could place them under a nonmetallic card table and by casually pressing the right location on a tabletop surface you could mysteriously control your DIY project.
For all Grove users (especially beginners), we provide you guidance PDF documents. Please download and read through Preface - Getting Started and Introduction to Grove before your using of the product.
Please visit our wiki page for more info about this product. It will be appreciated if you can help us improve the documents, add more demo code or tutorials. For technical support, please post your questions to our forum.