4 all cores: 2nd retro D9 Joystick Interface multiplex

[vossstef]

idea how to design a 2nd D9 retro Joystick interface multiplex.

• PMOD shape. Usable for boards as such with spare PMOD like TP20k, TM60k, TM138k Pro. Assume that user will select Dualshock PMOD or D9 Joystick PMOD for use and not both types at the same time.
• use two pcs 74LVC245 TSSOP-20 as 5V tolerant buffer with enable
• dedicated control line from core to each buffer. Single buffer at a time enabled ensured by core.
• 220R series resistors at buffer outputs to avoid excessive current drawn in case FPGA and buffer drive at the same time. e.g. user select Dualshock in OSD but plugs a D9 Joystick PMOD sharing the same interface to FPGA.
• idea would support TN20k cores as well.
• 3V3 to 5V converter (same as m0s pmod) driving the Joystick supply
• presently unused TN20k IO6 and IO7 (first idea) as multiplex control signal.
• if multiplex signals not driven use just single D9 use.
• Two Joystick buttons supported.

[vossstef]

early study prototype for a dual D9 Joystick to PMOD / SDRAM slot combo Adapter.

TN9k adhoc wiring via PMOD
TN20K adhoc wiring via PMOD
TP20K PMOD
TP25K SDRAM slot (support A2600 (VIC20) D9 Joystick use as no DRAM needed)
TM60K NEO 2nd SDRAM slot or PMOD (support A2600 (VIC20) D9 Joystick use and Dualshock at the same time)
TM138K Pro PMOD