Atari 2600 Controller Shield PCB Build Guide

By Kevin on May 22, 2025

Here are the build notes for my Atari 2600 Controller Shield PCB Design.

Recall from my design notes that this version doesn't deal with paddles very well.

Warning! I strongly recommend using old or second hand equipment for your experiments. I am not responsible for any damage to expensive instruments!

If you are new to Arduino, see the Getting Started pages.

Bill of Materials

PCB (GitHub link below)
2x 9-pin D-type connectors - PCB mounted (see photos and PCB for footprint).
Optional: Arduino headers: 1x6-way, 2x8-way, 1x10-way
Or: pin headers

The above photo shows the 9-pin D-type connectors from various angles. The spacings are as follows:

Pin spacing: 2.77mm
Spacing between pin rows: 2.84mm
Distance from pins to edge of connector: 7.7mm
Mounting hole distance to edge of connector: 9.12mm
Mounting hole distance: 25.0mm

Build Steps

It doesn't matter much whether the pin headers or D-type connectors are soldered first.

However, if using header sockets as shown in the photo above, then it makes more sense to fix these first as they need to be soldered on the same side as the D-types, but aren't as tall.

Testing

I recommend performing the general tests described here: PCBs.

A simple digital and analog read sketch can be used to quickly check the functionality.

For joysticks:

#define PINS 10
int p[PINS] = {2,3,4,5,6,8,9,10,11,12};

void setup() {
  for (int i=0; i<PINS; i++) {
    pinMode (p[i], INPUT_PULLUP);
  }
  Serial.begin(9600);
}

void loop() {
  for (int i=0; i<PINS; i++) {
    Serial.print(digitalRead(p[i]));
    Serial.print("\t");
  }
  Serial.print("\n");
  delay(200);
}

For paddles:

Note: this will require an additional resistor to GND from the corresponding analog input, for all paddles used. If a 1M resistor is used there is a more linear response, but the readings will only vary between 512 and 1023 (or thereabouts) corresponding to a read voltage of between 2.5V and 5V.

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

void loop() {
  for (int i=0; i<4; i++) {
    int aval = analogRead(A0+i);

    Serial.print(aval);
    Serial.print("\t");
  }
  Serial.print("\n");
  delay(100);
}

For keypads:

Note: this requires the keypad library which should be available by default with the Arduino environment.

#include <Keypad.h>

const byte ROWS = 4; //four rows
const byte COLS = 3; //three columns
char hexaKeys[ROWS][COLS] = {
  {'3','2','1'},
  {'6','5','4'},
  {'9','8','7'},
  {'#','0','*'}
};
// Port 1
byte rowPins[ROWS] = {11,10,9,8};
byte colPins[COLS] = {12,A0,A1};
// Port 2
//byte rowPins[ROWS] = {6,5,4,3};
//byte colPins[COLS] = {2,A2,A3};

Keypad customKeypad = Keypad( makeKeymap(hexaKeys), rowPins, colPins, ROWS, COLS); 

void setup(){
  Serial.begin(9600);
}
  
void loop(){
  char customKey = customKeypad.getKey();
  
  if (customKey){
    Serial.println(customKey);
  }
}

PCB Errata

There are the following issues with this PCB:

As already mentioned there is no real provision for reading paddles.

Enhancements:

Allow for a resistor and capacitor to mirror the original Atari 2600 circuit.

Find it on GitHub here.

Closing Thoughts

As is becoming customary, it appears I can't produce a PCB without at least one annoying issue. Even one as simple as this I managed to get the wrong sense for the connector for v0.1 and didn't notice until the signals weren't working!

The paddle issue was really just my misunderstanding (misreading) of the documented paddle circuit!

But pleasingly the Arduino built-in Keypad library "just works" with the keypad controllers and this simple version of the Arduino shield

Kevin