VIC20 living in a Gowin GW1NR-9 FPGA on a Sipeed Tang Nano 9k with HDMI Video and Audio Output.
Original VIC-20 core by MikeJ (Mike Johnson) and T65 WoS (Wolfgang Scherr)
Features:
- HDMI 720x576p @50Hz Video and Audio Output
- PS/2 Keyboard
- Retro D9 Joystick
By default cartridge ROM will be booted (see push button how to suppress).
- S1 push button Reset
- S2 Cartridge ROM disable (keep S2 pressed while power-on or excert a S1 push-button Reset, release after)
Prototype circuit with Keyboard can be powered by Tang USB-C connector from PC or a Power Supply Adapter.
Source code can be synthesized, fitted and programmed with GOWIN IDE Windows or Linux.
Basic testbench as a starting point in the TB folder (vic20_tb.vhd)
Script for compiling the Gowin library, sources and testbench in the simulation folder (sim_vic20.do).
For Simulation run execute_simulation.bat (Windows) or execute_simulation.sh (Linux)
see pin configuration in .cst configuration file
The bin2mi tool can be used to generate from a 8192 byte Game ROM new pROM VHDL code. For the ROM image i took had to remove the first byte in the generated HEX file indicating the VIC-20 ROM region (0xA0) before providing needed Memory initialization file to the IP Block generator.
- PS/2 keyboard has to be connected to 3.3V tolerant FPGA via level shifter to avoid damage of inputs ! Use e.g. 2 pcs SN74LVC1G17DBVR 5V to 3V3 level shifter. My Keyboard has internal pull-up resistors to 5V for Clock and Data Signals so didn't needed external ones.
- Joystick interface is 3.3V tolerant. Joystick 5V supply pin has to be left floating !- Tang Nano 5V output connected to Keyboard supply. Tang 3V3 output to level shifter supply.
Pinmap D-SUB 9 Joystick Interface
| Joystick pin | Tang Nano pin | FPGA pin | Joystick Function |
|---|---|---|---|
| 1 | J5 8 | 28 | Joy3 RIGHT |
| 2 | J5 7 | 27 | Joy2 LEFT |
| 3 | J5 6 | 26 | Joy1 DOWN |
| 4 | J5 5 | 25 | Joy0 UP |
| 5 | n.c. | n.c. | POT Y |
| 6 | J5 9 | 29 | FIRE B. |
| 7 | n.c. | n.c. | 5V |
| 8 | J6 23 | - | GND |
| 9 | n.c. | n.c. | POT X |
Pinmap PS2 Interface
| PS2 pin | Tang Nano pin | FPGA pin | PS2 Function |
|---|---|---|---|
| 1 | J6 10 | 77 | DATA |
| 2 | n.c. | - | n.c. |
| 3 | J6 23 | - | GND |
| 4 | J6 18 | - | +5V |
| 5 | J6 11 | 76 | CLK |
| 6 | n.c. | - | n.c |
Sipeed Tang Nano 9k
D-SUB 9 M connector
Commodore/Atari compatible Joystick
or alternatively 5D Rocker Joystick navigation button module
PS/2 Keyboard
PS/2 Socket Adapter Module
2 pcs SN74LVC1G17DBVR level shifter
Prototype Board
TFT Monitor with HDMI Input and Speaker