Stem measurement is vital since its diameter is related to development of tree as well as water content. Hence, in this study, PIC microcontroller based instrumentation is developed for measuring the changes of linear micrometer that represents the stem diameter changes. Here, the strain gauge is used as a sensor to detect the changes in micrometer for every 1μm changes. In addition, digital multimeter and digital oscilloscope are used for comparison and validation of the proposed PIC. Results attained proven that the system is capable to measure changes of stem diameter accurately.