Any Ideas /References On this Miniproject

[rinaishlene]

mex68kecb schematic

Hi,
I have been assigned to do this homework.

Assignment:to design a microprocessor based system using 68K that would
be able to test the functionalities of the logic gate such as AND ,OR ,NOR or other.


Input:Output from the gate
Outputisplay pass and fail on 2 digits seven segment display.If fail
display the pin number.


This is exact what my lecturer told me in the class.
She told us that we needed to find the circuit from any sources
available i.e the internet,books or we have to design it on our own.


We are very confused since this is the first time we have been
introduced to microprocessor.We so far learned the architecture of the
68K,how to write program using assembly language and also 68230
interfacing.The hre comes the project...some sort called mini project.


We are asked to use 68K microcontroller and 68230 PI/T for
interface(PI/T is provided in the lab)in this miniproject.I have a
circuit w/o 68K in it that is used to test NOR gate output.So can I
create another circuit using 68K to extract circuit output to be the
input of the 68K circuit which then could be interface with the 68230
PI/T?Thanks


Any ideas would be highly appreciated.


Rina

 

[VVV]

Basically, you need to be able to READ the levels on the gate (whatever its type), change them according to a truth table and decide if the output behaves correctly.

So, you need a way to execute input/ output operations using the 68k, that is some sort of interface with the external world. That is best done using a type of parallel interface. Some of the lines will be outputs from the interface to the inputs of the gate(s). Other lines will be inputs to the 68k, connected to the outputs of the gates.

Next, you write your code (in assembler, for example) to output all the possible combinations to the inputs (these are just output operations). For example, if you have 74x08 (4x 2-input gates) you need 8 output signals (for all the inputs of the gates) and 4 input signals (for all the outputs of the gates). Send to each gate the combinations: 00, 01, 10, 11. After each output operation (and some delay, to allow the gate to switch) read in the state of the outputs and decide if it is correct in each case: 0 for 00, 01, 10 and 1 for 11. Anything different means the gate(s) are bad. Since you know what input is connected to what pin on the package, you can tell what is wrong.

When switching from one type of chip to another, you may need to change the direction on some of the pins of your interface (make them inputs instead of outputs and the other way around).

This is the simplest thing to do, which I believe will be enough for a school project. A better tester would include an A/D to ensure the power supply to the chip is really 5V (because the gate may have its power shorted inside). Also, a better tester would include readback capability on the gate inputs, that is, you would also check the inputs really get to the level you want (00, 10, etc), because the gate may have the inputs shorted internally to the supply rails (either Vcc or GND). Finally, a good tester would also include a way to actually test the proper levels at the outputs, with the specified load (x mA, as per datasheet), as well as a way of measuring the gates' propagation delays, with the specified load capacitance. But this is all stuff to be dealt with in inductrial testers. For a school project, whose only objective is to find a BAD gate (regardless of what is bad), see description above.

 

[rinaishlene]

Thanks.Have u happened to know where can I get a schematic diagram of MEX68KECB schematic diagram? I will be using this board for my project.

Rina

 

[VVV]

Try this: **broken link removed**