NexGen: The New Lab: DB-25 pinout tester - I

2 Aug 2020

Well, I'm just flat tired of fighting with my DB-25M interface connectors, at first, I thought of LEDs with pull up resistors. After dinner, my mind wandered back to my cable tester, hey, an Arduino Mega, which I have a bunch of, has 52 digital pins. But wait I only need twenty-five. Sounds good to me. I have to start with a clean Mega as my donor, still has some wires which are a pain-in-the-you-know-what to unwrap without the right tool, and mine is currently MIA somewhere in the lab.

The Plan is stupidly simple.

First I will wire the connector to the Megas digital I/O pins 22 on the Mega to 1 on the DB25. Finishing with 46 on the Mega and 25 on the DB25. I already have a drilled ATRpolly for what I need.

Secondly, I can add an RS485 interface as well so I can check on that as well. Since my traffic has a byte for Source and Destination, I could, in fact, create a snoop tool just like we have for the ethernet.

Software

Pins.h

int pin[] = {   22, 23, 24, 25, 26, 27, 28, 29, 30, 31,
                    32, 33, 34, 35, 36, 37, 38, 39, 40, 41,
                    42, 43, 44, 45, 46 };

Modes.h

for (int step = 22; step < 47; step++) {

pinMode(pin[ step ], INPUT_PULLUP); }

DB25Tester.c

#include <Pins.h>
#include <Modes.h>

void setup() {
Serial.begin(9600);}

void loop() {
begin(9600);}
   int count;

    do {
       int temp[] = {0, 0, 0, 0, 0, 0, 0 ,0 ,0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
       for ( int count = 0; count < 26; count++) {
           temp[count] = digtalRead( pin[ count ]; }
      Serial.write(pin, 25);

}while(true);
}