An analog-to-digital conversion system has an analog-to-digital converter and a digital-filter system. The digital-filter system is connected to the output of the analog-to-digital converter. A processor is connected to the output of the digital-filter system so that the processor transparently receives filtered sample data in the native format of the analog-to-digital converter. An FIR filter circuit in the digital-filter system is connected to receive data from, and output filtered data to, a sample capture and data-type conversion circuit connected between the analog-to-digital converter and the processor. A configuration and control-register circuit is connected to the circuit for sample collection and data-type conversion, and to the FIR filter circuit, for selectively controlling the operation of the digital filter system according to parameters for data conversion and filter operation passed to the configuration and control-register circuit over a serial interface.