A2600Nano

The A2600Nano is a port of the MiSTer FPGA core of the Atari 2600 VCS to the Tang Nano 20k (Gowin GW2AR) with enhancements from the A7800 core such as cartridge type autodetect and the video stabilizer.

This is based on the C64Nano project and also relies on a M0S Dock µC being connected to the Tang Nano 20K. Alternately you can use a Raspberry Pi Pico or esp32-s2/s3 and use the FPGA companion firmware.

Original A2600 core by Retromaster
All HID, SDcard and µC firmware by Till Harbaum

Features:

• PAL 768x576p or NTSC 768x480p HDMI Video and Audio Output
• Scanline length auto adjust
• Cartridge type autodetect
• NTSC / PAL region autodetct
• Superchip autodetct
• USB Keyboard via µC
• USB Joystick via µC
• USB Gamepad Stick via µC as paddle emulation
  
• legacy D9 Joystick (Atari / Commodore digital type) MiSTeryNano shield
  
• Joystick emulation on Keyboard Numpad
  
• Dualshock 2 Controller Gamepad Keys & Stick as Joystick
  
• Dualshock 2 Controller Gamepad Sticks as paddle emulation (analog mode)
  
• Cartridge ROM loader boot default is homebrew 'Hunchy' Chris Walton

Planned features:

• ROM mapper control override via file extension
• Mouse as paddle support

Important

PROJECT IS STILL WORK IN PROGRESS!

HID interfaces aligned in pinmap and control to match FPGA-Companion.
Basically a µC M0S/BL616 / Raspberry Pi Pico RP2040 / ESP32-S2/S3 acts as USB host for USB devices and as an OSD controller using a SPI communication protocol.

Installation

The installation of A2600Nano on the Tang Nano 20k board can be done using a Linux PC or a Windows PC Instruction.

Cartridge ROM Loader

ROM can be loaded via OSD file selection.

Supported mappers

• Auto detected (00 F8 F6 FE E0 3F F4 P2 FA CV 2K UA E7 F0 32)
  

LED 2 to 4 are activated as hint in case an unsupported game (mapper) detected

single Button Joystick

• Button Trigger

four Button Joystick or Gamepad

• Gamepad Button Trigger A (DS2 circle) Trigger

• Gamepad Button Trigger B (DS2 cross) Paddle Trigger and enable

• Gamepad Button Trigger X (DS2 triangle) Paddle 2nd Trigger and enable

• Gamepad Button Trigger Y (DS2 square) revert Paddle mode to Joystick mode

• Gamepad Button START as core function START
  

• Gamepad Button SELECT as core function SELECT
  

Paddle

• DualShock 2 or USB Gamepad.
  

Core switches to paddle mode if paddle Trigger B or Trigger X is pressed.
Can be reverted by pressing Gamepad Button Trigger Y.

Keyboard

• Key F11 as core function START
  
• Key PAGE UP as core function SELECT
  

Push Button utilization

• S2 keep pressed during power-up to prevent FPGA bitstream load from FLASH.
  

• S1 reserved
  

OSD

invoke by F12 keypress

• Reset
  
• Cold Reset
  
• Audio Volume + / -
  
• Scanlines effect %
  
• Region switch Auto/NTSC/PAL
  
• HID device selection for Joystick Port
  
• Loader file selection
  
• Difficulty A, B Core switch
• Black & White Core video switch
• Joystick port swap
• Invert Paddle
• De-comb
• SuperChip Auto/off/on

Gamecontrol support

legacy single D9 Digital Joystick. OSD: Retro D9
or
USB Joystick(s) or Gamepad(s). OSD: USB #1 Joy or USB #2 Joy
or
Gamepad Stick as Joystick. OSD: DualShock2
left stick for Move and square triangle cross circle Buttons for Trigger:

Buttons	-	-
square Trigger 1	Up	cross Trigger 2
Left	-	Right
triangle Trigger 4	Down	circle Trigger 3

or Keyboard Numpad. OSD: Numpad

0 Trigger	8 Up
4 Left	-	6 Right
-	2 Down	-

or Mouse. OSD: Mouse
not supported yet

or Dualshock2 Gamepad left stick as Paddle. OSD: DualShock2
cross / triangle Trigger
You have first to set the DS2 Sticks into analog mode by pressing the DS2 ANALOG button.
Mode indicated by red light indicator.
Configure DIGITAL mode (press ANALOG button again) when using the Joystick mode again.

LED UI

LED	function	TN20K	TP20K	TP25K	TM138K	TN9k
0	Cartridge selected	x	-	-	-	-
1	reserved	x	-	-	-	-
2	Game unsupported	x	-	-	-	-
3	Game unsupported	x	-	-	-	-
4	Game unsupported	x	-	-	-	-
5	Game unsupported	x	-	-	-	-

LED 2 to 4 are activated as hint in case an unsupported game (mapper) detected

Multicolor RGB LED

• green      all fine and ready to go
  
• red          something wrong with SDcard / default boot image
  
• blue        µC firmware detected valid FPGA core
  
• white      -
  

Powering

Prototype circuit with Keyboard can be powered by Tang USB-C connector from PC or a Power Supply Adapter.

Synthesis

Source code can be synthesized, fitted and programmed with GOWIN IDE Windows or Linux.
Alternatively use the command line build script gw_sh.exe build_tn20k.tcl

HW circuit considerations

Pinmap TN20k Interfaces
Sipeed M0S Dock, digital Joystick D9 and DualShock Gamepad connection.

Pinmap D-SUB 9 Joystick Interface

• Joystick interface is 3.3V tolerant. Joystick 5V supply pin has to be left floating !
  

Joystick pin	IO	Tang Nano pin	FPGA pin	Joystick Function
1	2	J6 10	25	UP
2	1	J6 9	28	DOWN
3	4	J6 12	29	LEFT
4	3	J5 11	26	RIGHT
5	-	-	-	POT Y
6	0	J5 8	27	TRIGGER
7	-	n.c	n.c	5V
8	-	J5 20	-	GND
9	-	-	-	POT X

Pinmap Dualshock 2 Controller Interface

DS pin	Tang Nano pin	FPGA pin	DS Function
1	J5 18	71 MISO	JOYDAT
2	J5 19	53 MOSI	JOYCMD
3	n.c.	-	7V5
4	J5 15	-	GND
5	J5 16	-	3V3
6	J5 17	72 CS	JOYATN
7	J5 20	52 MCLK	JOYCLK
8	n.c.	-	JOYIRQ
9	n.c.	-	JOYACK

Getting started

In order to use this Design the following things are needed:

Sipeed M0S Dock or Raspberry Pi Pico RP2040 or ESP32-S2/S3
Sipeed Tang Nano 20k
microSD or microSDHC card FAT/exFAT formatted
TFT Monitor with HDMI Input and Speaker

HID and Gamecontrol Hardware option	TN20k	alternative option	Primer 25K	Mega 138K	Primer 20K
USB Keyboard	USB-C to USB-A adapter	4 port mini USB hub	x	x	x
USB Joystick(s)	4 port mini USB hub	-	x	x	x
USB Mouse	4 port mini USB hub	-	x	x	x
USB Gamepad	4 port mini USB hub HS8836A	-	x	x	x
Commodore/Atari compatible retro D9 Joystick	MiSTeryNano shield	D-SUB 9 M connector, breadboard to wire everything up, some jumper wires	-	-	-
Dualshock 2 Controller Gamepad	Gamepad Adapter Board (Sipeed Joystick to DIP)	breadboard to wire everything up and some jumper wires	-	x	x