Logic Analysis is used with digital systems, particularly microprocessor based, to investigate complex data patterns in multi-channels. A Logic Analyser can capture data from a number of channels, trigger on a pre-defined event and display the information in a number of different formats.
An Oscilloscope can display typically up to 4 channels of data (analogue or digital) against time and is mainly used to measure signal amplitude & period in detail. The display is an analogue representation of the input signal.
The Logic Analyser can capture many more channels of data. This is essential where 8, 16, 32, 64 bit wide data and address buses are concerned. The HP 1630G can capture up to 65 channels. Modern Logic Analysers can capture 100's of channels.
Acquisition rate is the maximum sampling speed of the Logic Analyser. The 1630G provides data sampling up to 25MHz for State analysis and up to 100MHz for Timing analysis. Modern Logic Analysers can work up to 50GHz.
"Timing" mode is similar to an Oscilloscope, where signals are captured such as pulses, transients, etc. An internal clock is used to sample the data asynchronously. This mode is used where the timing relationship between input signals is required.
"State" mode is used to capture data and address bus channels. A clock signal from the Device Under Test (DUT) is used to sample the data synchronously.
Both modes can be triggered on a variety of events such as from a positive edge on a clock signal, or a specific 8-bit word on a data bus, or even Boolean logic.
The Logic Analyser provides a digital display of the input signal in terms of 'high' and 'low', it does not provide any analogue information such as rise & fall times. Storage is available to display the information in different formats. Waveform display is similar to an Oscilloscope and is used for timing analysis. Listing display provides state analysis in alphanumeric form, ie binary/octal/decimal/hex/etc.
A useful reference source is "The XYZs of Logic Analysers" available from Tektronix.
A short review of how far I have got with this project and what's holding me up.
Logic Analysis Test Equipment
A range of test equipment was available from HP for logic analysis including:
HP 5004A Signature Analyser
After acquiring, repairing and testing the equipment, these are my working notes on operating the logic analyser.