This study presents the embedded microcontoller of data acquisition unit, performance analysis, and wireless data transfer capability of the semi active above knee joint with pneumatic cylinder developed in Hacettepe University Biomedical Research Laboratory. For this purpose an embedded microcontroller based data acquisition card has been designed and programmed in order to have an adaptive capability for coping with different phases of the gait. This prosthesis also responses the instantaneous gait velocity alterations and it adjusts the damping variable of the pneumatic cylinder via a stepper motor. System detects the related gait phases and gait velocities from the signal of inertial measurement unit (IMU). Printed board tests and gait performance evaluation tests are conducted with associated Bluetooth wireless transfer unit. It has been shown that the kinematic variables have been measured and analyzed successfully by this embedded wireless system.