| In the field of industrial production and scientific research, reliable andprecise measuring means are needed. In the recent years, new intelligentinstruments are equipped with GPIB (General Purpose Interface Bus) interface,making it connected with the computer and forming automatic measuringsystem. The system not only improves the measuring precision but also has thedata processing capability and replaces the hardware with the software tofulfill functions that the hardware cannot implement.Present foreign instrument and equipment furnished with GPIB interfacegenerally, or had GPIB interface to be selectable, the forming of the interfacegenerally adopts the special purpose interface chip; domestic instrument haveless this configuration,and relevant materials are too rare, but with theapplication of computer become wider, the intelligent equipment that bringsingle-chip computer or microprocessor become more, how to realize a GPIBinterface by adding or just adding a small amount of hardware and software,satisfying the need of the equipment contacting with the external world whichis exactly the problem that we will solve . adding GPIB interface to traditionalsemiconductor constant-temperature controller , making them becomeprogram-controlled instrument which can combine with the computer andform auto-test system .It's already becomes one of the important developing direction to set upauto test system by programmable device with GPIB and change thecharacteristics of traditional device that manual and used in signal device, andalso do good to exertion of device function. But most programmable deviceproduced in our country didn't deploy GPIB interface panel, which is andisadvantageous factor to make up auto test system. The GPIB interface paneldesigned in this paper can be transplant easily and it's software controlcompletely accord with IEEE488.2 interface criterion, just small programneeded can be added into programmable device to establish auto test system.GPIB (the bus of interface in common use) is a contact between everykind of equipments to communication in automatic test system, which wasdetermined as IEEE488 and IEC625 standard, and was the standard of busesinterchangeably used extensively in the world, it belongs to the running sideby side , its function is to join various kinds of equipment selected for use for acertain measurement purpose , making up an automatic test system under thecomputer's controls. The instrument with communication interface of GPIB isespecially suitable for setting up the extensive automatic test system. It's already becomes one of the important developing direction to set upauto test system by programmable device with GPIB and change thecharacteristics of traditional device that manual and used in signal device, andalso do good to exertion of device function. But most programmable deviceproduced in our country didn't deploy GPIB interface panel, which is andisadvantageous factor to make up auto test system. The GPIB interface paneldesigned in this paper can be transplant easily and it's software controlcompletely accord with IEEE488.2 interface criterion, just small programneeded can be added into programmable device to establish auto test system. At present, there are many special large-scale integratey circuit to carryout GPIB interface and they are different in capability. We adopt nat9914 ofNI company to be GPIB interface chip after considering the function andprice.While we designed GPIB interface board facing program-controlledinstrument, consider the performance of the chip and price factor synthetically,NAT9914 which has selected NI Company for use is as GPIB interface chip.NAT9914 is designed to accomplish the interface function that determined byIEEE488 and 488.2. Designed the chip in interface function that 2 standardsdefine. Through set up and finish IEEEE488 interface function to betweencontrol and position , state of register those NAT9914, those registers increasethe software and urge and simplify the hardware and software design.NAT9914 has the function of intact talking , listening to , accusing of, and iscompatible with NEC7210, TMS9914 chip Making NAT9914 as interface board key chip , combining such chips as89C51 , 74LS373 , SN75160 , SN75162 ,etc. develop GPIB interface board byoneself, this interface board has good currency and portability, and is flexiblein usage, . At the same time in order to test the function of the interface board,designed the circuit board of testing, this tests board is made up of chips suchas keyboard , display ,and 89C51 ,etc.. Then on the basis of analyzing the semiconductor laser instrumentconstant temperature controller, combining the advanced intellectualinstrument design method both at home and abroad, have proposed the designplan of the constant temperature controller of laser instrument ofprogram-controlled semiconductor, providing the circuit block diagram ofglobal design. From the basic principle of GPIB interface IEEE488 protocol, themeanings of different functions are analyzed and waveform pattern of mainfunctions are given to gain close and interactive relationship among thedifferent functions. From different angles, three handshake lines'principleanalyzed to lay the foundation for the software design. Various functions,signal source and architecture of GPIB interface protocol stipulation aredescribed in full and detail. Semiconductor laser instrument is receiving the extensive applicationin all field day by day now. The semiconductor laser instrument, as the lightsource of the mere amplifier, people always hope it can work steadily in along-term, but semiconductor laser instrument is very sensitive totemperature, fluctuation of environment temperature can cause and supplythe fluctuation of the electric current with not merely, and can makethreshold value electric current , quantum efficiency of laser instrument ,output wavelength and output power take place heavy change.So offeringconstant temperature of control for it when the semiconductor laserinstrument work. Some foreign companies have developed the...
|
PDF Full Text Request