Image Number 13 for United States Patent #6901470.
A data I/O system includes first and second function blocks connected to a system bus, which allows the function blocks to communicate with a processor. Each function block includes a D/A converter for outputting an analog signal and a waveform generator that provides a digital signal to the D/A converter. The waveform generator includes a memory control circuit and an address generation circuit. The memory control circuit has an address register and a data register, both of which are connected to the system bus, and a memory connected to the address register and the data register. The address generation circuit is connected to the address register and includes a control register, an up-down counter, and a comparator. The address generation circuit repetitively provides a circulating address signal to the address register. The function blocks relieve the processor of some of its processing load, but do not require additional I/O port addresses of the system.