The paper describes the development of a microsatellite attitudedetermination and control subsystem (ADCS) and verification of itsfunctionality by processor-in-the-loop (PIL) method. The role of ADCS is toprovide attitude control functions, including the detumbling and stabilizingthe satellite angular velocity, and as well as estimating the orbit and attitudeinformation during the satellite operation. At NCKU, Taiwan, a 30 kgexperimental micro satellite named CKUTEX is being developed. ForCKUTEX, the operation of the ADCS consists of three modes which areinitialization mode, detumbling mode, and normal modes, respectively.During the initialization mode, ADCS collects the early orbit measurementdata from various sensors so that the data can be downlinked to the groundstation for further analysis. During the detumbling mode, ADCSimplements the magnetic control method to decrease the satellite angularvelocity. During normal mode, ADCS provides the attitude determinationfunction for the estimation of the satellite state. In the beginning of theADCS design, Software-in-the-loop (SIL) simulation is used for ADCSdesign verification. In addition to SIL simulation, a Processor-in-the-loop(PIL) test platform has been set up for the verification test of the designedADCS hardware. The PIL platform contains a dynamic simulator and areal-time microcontroller, as well as some interfacing circuitry. Thedynamic simulator is capable of performing simulation of the spaceenvironment, orbit dynamics, attitude dynamics, and sensor/actuator models.The controller/estimator of ADCS is a realization of the embeddedmicrocontroller for attitude determination and control. In this paper, therequirements of CKUTEX ADCS will be briefly reviewed. The design andimplementation of CKUTEX ADCS will also be described. Furthermore,the design of the ADCS design can then be verified by the PIL test and theperformance of the ADCS can be observed from the simulation results.