Development Of CPCI Four-channel Isolated Counter

The CPCI counter module is one of the most commonly used modules to set up amilitary automatic test system, widely used in frequency measurement, periodmeasurement and time string measurement. Ground reference is different between testsystem and the system which is under test, so isolation is often needed. The current shelfproducts are often difficult to meet the environmental adaptability and reliabilityrequirements of military systems. Therefore, the development of CPCI isolation countermodule which meets the requirements of our military automated test system is of greatsignificance.Based on functional requirements and technical specifications, we proposed theoverall design of the the CPCI isolated counter module. Choose TMS320DM642DSP asthe host CPU and use its internal PCI interface completed the CPCI interface design.Effectively reduce the module size, shorten the development cycle and reduce thedifficulty of developing.Based on functional requirements and technical specifications, the overall design ofthe the CPCI isolated counter module is proposed. Selected TMS320DM642DSP as thehost CPU and use its internal PCI interface to complete the CPCI interface design, allthese effectively reduce the module size and shorten the development cycle and reducethe difficulty of development. Through the design of channel selection circuit, digitaldebounce circuitry and polarity selection circuit, the gate time circuit and counter circuit,Frequency measurement, period measurement, pulse-width measurement, time-intervalmeasurement and time string measurement, making the design compact and theexpansion convenient. Using a comparator with hysteresis improved anti-jammingcapability, the design of the front-end conditioning circuitry, the comparator circuit tocompare the level converter circuit, level generating circuit to achieve a front-end signalprocessing. All components used industrial grade devices meet the requirements of theenvironmental conditions.On the software side, the DSP firmware is developed according to the modulefunction in the software side, the counter module’s drivers and test panels were written inLabwindows/CVI. Hardware configuration and test achieved through the test panels.The test of the module’s hardware and software results show that the design of theCPCI counter module is rational and its functionality and performance meet the designrequirements.