Step 1: Background talk
On the other hand, I had a spare NES 'generic' controller bought in a flea market that was working perfectly.
I thought about using a microcontroller to convert the serialized signals in NES joystick to parallel signals required by Atari 2600, but then I wondered that if instead of a custom microcontroller board I could use an Arduino. So other people without many skills in electronics could assemble their own adaptors with easy.
Step 2: The 'big' Circuit
Bill of Materials:
- 1 Arduino (any version will do)
- 2 DB-9 Male connectors. One for the NES 'generic' Controller and another to the test dongle
- 1 DB-9 Female connector, to plug into the Atari.
- 5 Leds for the test dongle
- 5 resistors 330 Ohms 1/4 Watt for the test dongle
- A buch of wires
Of course is it possible to reuse the old Atari Joystick cable instead of the DB9 female plus wires.
It is also possible to cut the NES controller cable and connect directly to the Arduino, but you should identify the wires in the cable.