SRF02 ultrasonic sensor [Discontinued] _ARD_SHIELD_PROTO Do not try to recharge

Do not try to recharge non-rechargeable Lithium coin batteries

two for the keyboard

RPLIDAR A2 adopts laser triangulation ranging principle and with high-speed RPVision range engine

You'll need to solder the header onto the PCB to use in a breadboard but it's fairly easy and takes only a few minutes even for a beginner

SRF02 ultrasonic sensor [Discontinued] _ARD_SHIELD_PROTO Do not try to rechargeThis low cost ultrasonic ranger has both I2C and Serial interfaces. New AutoTune algorithms intelligently back the minimum range right up to the transducer ringdown for the very best performance possible, automatically, in the background, and with no calibration cycles necessary. Additional new commands allow for separate burst and ranging control. The SRF02 features both I2C and a Serial interfaces. The serial interface is a standard TTL level UART