Aim\ To achieve the high (10 bit) precision automatic measurement for widerange non linear parameter

using an 8 bit A/D convertor (ADC0809). Methods\ In hardware

the range is devided into four equal parts. Each amplifiers with separately adjustable reference point and amplification. Each signal takes up one channel of the ADC0809. The software automatically switches the range by compared four parameters and displays the result. Results\ By way of trial and adjustment

the measuring error can be reduced to less than 0.1 ℃ in the range of (0～100) ℃. Conclusion\ For the measurement of nonlinear parameters(such as temperature)which does not require high response speed

the method can improves the measuring accuracy.