SN76489 USB

I wanted to make a slightly more modern implementation of my SN76489 USB. The main changes are: Teensy LC, 3.2, 3.6 compatibility, and no need for an external crystal oscillator as the Teensy generates a 3MHz signal for the timing of the SN76489.

The hardware connection is as follows:

• Pin 0 to SN76489 write enable 
• Pin 3 to SN76489 clock input
• Pin 4 - 11 to SN76489 D0 to D7
• Teensy 5V to SN76489 5V
• Teensy ground to SN76489 ground and output enable

Download the code from here: https://github.com/little-scale/arduino-sketches/blob/master/sn76489_USB.ino