Hello, i am searching for a solution to creating a multi pin (58) cable tester that will be able to detect opens and shorts to other wires. Any analog way that I have found of doing this is for no more than 8 wire testers. So my thought is I could use a Arduino to do this. I am new to Arduino and am unsure of what, if any, Arduinos could do what I need. I would like to either have a lcd display with this to show the problem wires or have LED indicators to do the same.
If anyone has any input I would greatly appreciate some guidance.
Pretty simple task in software but it does require some external I/O pin expansion ICs to do in a straight forward manner. You need to build a 58 bit serial in parrallel out output shift register and a 58 bit parrallel in serial out shift register. The cable would plug between the outputs and inputs of the two shift registers. Your software would shift out 58 bits with only one bit set high for each test, and read all 58 input bits and check that only the corresponding bit reads high on the inputs and all others should read low. If the one bit does not read high then there is a open path and if any other bits read high they are shorted to the first bit. Then shift out the next test of 58 bits with only the second bit set high and read the inputs again. Lather, rinse, repeat for all 58 bit positions and your test is complete. Make sense?
retrolefty:
The cable would plug between the outputs and inputs of the two shift registers. Your software would shift out 58 bits with only one bit set high for each test, and read all 58 input bits and check that only the corresponding bit reads high on the inputs and all others should read low.
In addition to testing each cable individually, shouldn't you be testing some multiple combination of bits set to guard against cross talk and noise? You don't want to test all 2^59 combinations, but I would think you would want to test some of the combinations.
retrolefty:
The cable would plug between the outputs and inputs of the two shift registers. Your software would shift out 58 bits with only one bit set high for each test, and read all 58 input bits and check that only the corresponding bit reads high on the inputs and all others should read low.
In addition to testing each cable individually, shouldn't you be testing some multiple combination of bits set to guard against cross talk and noise? You don't want to test all 2^59 combinations, but I would think you would want to test some of the combinations.
Well he only stated a need for detecting good continuity for each conductor and no shorts to any other conductors. Cross talk and noise are going to be inherent with the cable.connector material used and anyway would require AC testing and analysis and not something needing to be tested for a simple pass/fail of the basic wiring connector/conductor after construction or possible damage testing after cable use. I do think you need to test all possible combinations and it will proceed a lot faster then you think, it's a 16 Mhz micro for darn sakes.
By the way it's one cable with 58 conductors, not 58 cables.
I would use TPIC6C595 as the output shift registers, with 74HC165 as the input shift registers with pullup resistors on their inputs. Pull one line low at a time and make sure only 1 low at a time is received.
Then if there are shorts, only open drain outputs are being pulled low, and not an active high output fighting against active low outputs which will yield inconclusive results.
You will need 8 of each type, a 0.1uF power pin decoupling cap for each device, and a pullup resistor for each pin. Individual resistors are cheap, or a bussed resistor network can be used to save space.
Connect pin 16 to +5V, the rest to 74HC165 inputs.
