It adopts Bluetooth 2.1+EDR standard. In Bluetooth 2.1, signal transmit time of different devices stands at a 0.5 seconds interval so that the workload of bluetooth chip can be reduced substantially and more sleeping time can be saved for bluetooth.
Reed Switch is a special switch and a main component for reed relay and proximity switch. Reed switch is usually comprised of two soft magnetic material and metal reed contacts which will disconnect itself when there is no magnetic. In addition, some reed switches are also equipped with another reed acting as the third normally-closed contact.
The DRV8825 features adjustable current limiting, over-current and over-temperature protection, and six microstep resolutions (down to 1/32-step). It operates from 8.2-45V and can deliver up to approximately 1.5A per phase without a heat sink or forced air flow (rated for up to 2.2 A per coil with sufficient additional cooling).
This is a special LED module. When you connect it to ARDUINO development board, after programming, it can emit beautiful light. Of course, you can also control it using PWM. It will be like fireflies at night. Isn’t cool? You can also combine it with other sensors to do various interesting interactive experiments.