This wireless solution for high-precision temperature measurement is achieved through the combination of an RL78/G1D microcontroller with a built-in Bluetooth Low Energy-compliant 2.4GHz RF transceiver circuit and an RL78/I1E microcontroller with a built-in 24-bit delta-sigma AD converter. This solution makes it possible to send highly precise (to two decimal places) measurement data to a smartphone that has a built-in Bluetooth Low Energy (BLE) function. Besides temperature, this solution can also be expanded to pressure, weight and flow rate measurements, and more, so it can also be used in industrial and agricultural applications.