This paper describes the architecture and protocol of a digital stimulator which is intended to realize a highly flexible stimulation waveform pattern. The flexibility is provided by programmable stimulation profiles such as pulse duration, frequency, polarity, amplitude level, arbitrary wave shape, train of pulses and different types of wave patterns among stimulation sites. The programmable stimulation data is therefore divided into two parts, global and local stimulation data. The global data which defines the timing of pulse duration and wave shaping, are sent sequentially to all stimulation sites using 5-bit control commands. Local stimulation data defines the initial amplitude setting and is stored at each active stimulation cell. At each stimulation site, the amplitude level can be changed during the stimulation process and consequently it generates an arbitrary wave shape. Without the need of a large memory size, the proposed simple design architecture generates not only arbitrary stimulation waveforms, but also trains of pulses as well as different types of stimulation patterns among stimulation sites are enabled.