Use the SNES/NES controllers

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Revision as of 06:21, 12 March 2025 by 1BitFeverDreams (talk | contribs) (Created page with "== NES and SNES controllers == The F256 machines can use these controllers provided they are equipped with an optional [https://c256foenix.com/product/fnx4n4s/?v=5435c69ed3bc FNX4N4S breakout adapter]. The official gamepads of yesteryear work without issue with this and are plentiful in the used market. Third party modern recreations are sometimes flaky or not working at all. Share you discoveries in the discord! Super famicom gamepads work very well as substitute...")
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NES and SNES controllers

The F256 machines can use these controllers provided they are equipped with an optional FNX4N4S breakout adapter.

The official gamepads of yesteryear work without issue with this and are plentiful in the used market.

Third party modern recreations are sometimes flaky or not working at all. Share you discoveries in the discord!

Super famicom gamepads work very well as substitute for regular SNES gamepads.

Registers

Register Name R/W Address NES/SNES Description
PAD_CTRL W 0xD880 both Used to trigger a reading and setting the NES/SNES mode
PAD_STAT R 0xD880 both Used to verify if the triggered polling of gamepad state is done yet
PAD0 R 0xD884 both Buttons statuses: if cleared, they are pressed. If set, they are unpressed.
PAD0_S R 0xD885 SNES Same deal; unused by NES. Consult button table below
PAD1 R 0xD886 both Buttons statuses: if cleared, they are pressed. If set, they are unpressed.
PAD1_S R 0xD887 SNES Same deal; unused by NES. Consult button table below
PAD2 R 0xD888 both Buttons statuses: if cleared, they are pressed. If set, they are unpressed.
PAD2_S R 0xD889 SNES Same deal; unused by NES. Consult button table below
PAD3 R 0xD88A both Buttons statuses: if cleared, they are pressed. If set, they are unpressed.
PAD3_S R 0xD88B SNES Same deal; unused by NES. Consult button table below

Control register

Register Name R/W Address Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
PAD_CTRL W 0xD880 NES_TRIG - - - - MODE - EN
PAD_STAT R 0xD880 NES_TRIG DONE - - - MODE - EN

Control register bit states:

Bit Name If set to 1 If cleared to 0
NES_TRIG Launches the polling of the states of all buttons Stops polling the states of all buttons
DONE The states of the buttons are ready to be read The states of the buttons are not ready
MODE SNES data will be used to populate the PAD registers NES data will be used to populate the PAD registers
EN Enables the gamepads Disables the gamepads

Button table

MODE NES/SNES Address Pad Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
0 NES 0xD884 0 A B Select Start Up Down Left Right
0 NES 0xD886 1 A B Select Start Up Down Left Right
0 NES 0xD888 2 A B Select Start Up Down Left Right
0 NES 0xD88A 3 A B Select Start Up Down Left Right
1 SNES 0xD884 0 B Y Select Start Up Down Left Right
1 SNES 0xD885 0 A X L R
1 SNES 0xD886 1 B Y Select Start Up Down Left Right
1 SNES 0xD887 1 A X L R
1 SNES 0xD888 2 B Y Select Start Up Down Left Right
1 SNES 0xD889 2 A X L R
1 SNES 0xD88A 3 B Y Select Start Up Down Left Right
1 SNES 0xD88B 3 A X L R

Note: L refers to the left shoulder button and R refers to the right shoulder button.

Usage

Example 1: polling a NES controller in PAD0 position and checking if A is pressed:

POKE(PAD_CTRL, 0b10000001); //trigger, nes mode, enabled
while((PEEK(PAD_STAT) & 0x40) == 0) //loop while this bit is cleared
      ;
if((PEEK(PAD0) & 0x80) == 0) reactToAPressed();
POKE(PAD_CTRL, 0b00000001); //clear trigger

Example 2: polling a SNES controller in PAD2 position and checking if X is pressed:

POKE(PAD_CTRL, 0b10000101); //trigger, snes mode, enabled while((PEEK(PAD_STAT) & 0x40) == 0) //loop while this bit is cleared

     ;

if((PEEK(PAD2_S) & 0x04) == 0) reactToXPressed(); POKE(PAD_CTRL, 0b00000101); //clear trigger

Example 3: polling both types of controller in rapid succession (allows the usage of all 8 controllers!)

//NES section POKE(PAD_CTRL, 0b10000001); //trigger, nes mode, enabled while((PEEK(PAD_STAT) & 0x40) == 0) //loop while this bit is cleared

     ;

//section where reactions are made to the various NES presses POKE(PAD_CTRL, 0b00000001); //clear trigger

POKE(PAD_CTRL, 0b10000101); //trigger, snes mode, enabled while((PEEK(PAD_STAT) & 0x40) == 0) //loop while this bit is cleared

     ;

//section where reactions are made to the various SNES presses POKE(PAD_CTRL, 0b00000101); //clear trigger