Arduino Uno and Leonardo with Arduino IDE 1.0.5 r2 and 1.8.2. 2. More details, please click this link: <https://www.dfrobot.com/wiki/index.php/Gravity:_Analog_TDS_Sensor_/_Meter_For_Arduino_SKU:_SEN0244> ***/#defineTdsSensorPin A1#defineVREF 5.0// analog reference voltage(Volt) o...