Powerful timing generator using mono-chip timers: An application to pulsed nuclear magnetic resonance

Abstract

We present a 10 line–7 MHz timing generator built on a single board around two LSI timer chips interfaced to a 16‐bit microcomputer. Once programmed from the host computer, this device is able to generate elaborate logic sequences on its 10 output lines without further interventions from the CPU. Powerful architecture introduces new possibilities over conventional memory‐based timing simulators and word generators. Loop control on a given sequence of events, loop nesting, and various logic combinations can easily be implemented through a software interface, using a symbolic command language. Typical applications of such a device range from development, emulation, and test of integrated circuits, circuit boards, and communication systems to pulse‐controlled instrumentation (radar,ultrasonic systems). A particular application to a pulsed Nuclear Magnetic Resonance(NMR) spectrometer is presented, along with customization of the device for generating four‐channel radio‐frequency pulses and the necessary sequence for subsequent data acquisition.