This is a Test Circuit for Logic Analyzer software, with the Simple port circuit. The VB Logic Analyzer works, but is just an example program to test and learn.
The speed at which the logic state changes say like 10 M Hz while probing even a PIC or 89C51, is too fast for this circuit. For that, the incoming data has to be spooled or stored in RAM at real time, by the external Hardware itself.
Test Circuit for Logic Analyzer software – del20006
As this is a Parallel Port Interface, an Embedded High Speed Digital RAM Storage of Multiple Logic input Channels with Signal Conditioning in the front end, could do the job. This is the minimum, if you want to program the rest of the instrument on Computer Software. Here is one you can see from Bitscope using USB or Ethernet.
Printer Port Circuit to see the inputs logic state and drive a few outputs. The preset control program helps test out the circuit operation. Use safe 5V Levels.
Simple Printer Port Interface, Input-Output – del20005
So i made some example circuits and VB programs for students. A demo Milli Volt source, Digital Voltmeter and Logic Analyzer examples for learning, are on these pages. I have tried to derive power from PC itself in this circuit, Care should be taken not to short circuit or apply any voltages above 5V to PC Port Pins.
74HCT373 is the only chip used to interface the real world with the PC Parallel port. The Inputs to this chip are protected with Resistors and Zeners. 3 outputs of PC are also monitored using LEDs. This gives you a IO interface for experimenting. Below is a Preset counter simulation that you can use with this circuit for testing. Schmitt Triggers and Signal Conditioning may be required for Noisy and Non-Sandard Inputs.
The basic digital circuits are Flip Flop and Counter, both are here. This circuit can be cascaded to make even a 6 digit event counter, even a simple frequency counter can be made.
These are best done with microcontrollers today. Then what if you have to design your own microcontroller on a FPGA, so the basics have to be sound, hence you have to know what gates, flip flops and counters are.
see the seven segment display. Inc, Dec, and Set buttons are momentary acting and Clk Button is latching type. The Dip Switch in the also can be set.
a. – Set the DIP Switch as you like and then Press the Set button. The BCD value will be at the 4029 output, The Decimal value will be seen in the seven segment Display. Now try for different dip switch settings and see the BCD and Decimal output.
b. – Now Press The Inc and Dec pushbuttons. Set it to Increment up-count or Decrement which is down-count. This is a simple flip flop control.
c. – Now Click the Clk – clock or count button, the switch will latch, press it again to release. If you toggle it once the counter will get a single pulse and it will count it, see the BCD and decimal displays. Now you turn it on and leave it, the counter will keep counting one per second till you turn it off, the clock nand gate is wired to be an oscillator.
The decimal point LED of display is given to Carry Out pin of 4029 so observe this at 9 and 0 or transitions.
Add 104 CD, 0.1uF ceramic disc cap to all the ICs across the supply pins. Also add a 104 CD cap across Inc switch and one across the Set switch for power on default settings.
See a Tutor Digital up down BCD counter that will help you take the first step in digital electronics.
This is an example of a cascaded or sequential timer, here two CD4541 are forming a two stage timer. You can add more in a chain, but better to use a microprocessor or Microcontroller for such a purpose. But make sure EMI-RFI immunity is high for these circuits or wrong resets and sets can make a machine like an Oven or Environment Chamber malfunction and even ruin the job.
Two Stage Sequential Timer – del90004
U5B a flip-flop is used for the control switches Start and Stop to prime or shutdown the sequential cycle. The first timer U2 sets the flip-flop or register U5A after a period T1, this register turns the relay on thru Q3. The second timer U4 which was triggered by the first will reset the U5A after time period T2, U5A then shuts down relay. U5A also then resets entire process thru U3C and U3D.