Interface a serial 12-bit ADC to a PC

摘要

Over the years, ic vendors have devised various ways of effecting interfaces and paying special attention to reducing the number of ICs' interface-I/O pins. The MAX187 is one such device, a 12-bit A/D converter. You can create an interface to this ADC using serial data-communications techniques. Analog-to-digital conversion and data transfer from MAX187 require only three dig-ital-I/O lines. You can create a simple interface between the MAX187 and a PC using the computer's Centronics printer port (Figure 1). You enable or disable the MAX187 by setting the SHDN pin (Pin 3) to high or low level, respectively. If you leave this pin open, then the internal reference (4.096V) becomes disabled, and you must apply an external voltage reference to REF (Pin 4). Otherwise, this pin connects to a 4.7-μF bypass capacitor, C_1.