SUPER NINTENDO ENTERTAINMENT SYSTEM: PINOUTS & PROTOCOL
Contents:
* Chapter 1) About the Author
* Chapter 2) Introduction
* Chapter 3) SNES Multi-out cable connector pins.
* Chapter 4) SNES Controller cable connector pins.
* Chapter 5) SNES Controller Communication Protocol
* Chapter 6) SNES Controller Button-to-Clock Pulse Assignment
[Document Version: 1.01] [Last Updated: 3/26/96]
_________________________________________________________________
CHAPTER 1) ABOUT THE AUTHOR
Author: Jim Christy
Version: 1.01
E-Mail:
[email protected] _________________________________________________________________
CHAPTER 2) INTRODUCTION
For all you game hardware enthusiasts out there, I took the
opportunity this weekend to put a scope on my Super Nintendo
connectors and find out what is going on. Because the standard
Multi-out cable connector only has internal contacts for the audio and
video signals, I had to find some more push-in gold contacts at a
local store to fully break out all the signals. It appears easier to
do this than make your own connector.
In short, I found that in addition to S-VHS, the multiout also
supports RGB and sync. I also got the controller pinouts and protocol,
which opens up some interesting possibilities. One could rather easily
construct a "macro recorder" that records your exact button presses
for a game sequence and allows you to play them back. They will be
time-accurate by definition of the protocol, and depending on how
random the game plays, you should be able to replay those sequences
that get boring, and then take over control when you want.
If all of this is already well known, then sorry for the waste of net
bandwidth...
_________________________________________________________________
CHAPTER 3) SNES MULTI-OUT CABLE CONNECTOR PINS.
These are numbered the way Nintendo did, and the view is looking back
"into" the connector on the CABLE.
1 3 5 7 9 11
| | | | | |
| | | _ | | |
--------------------/ \--------------------
/ \
| |
| |
\ /
-------------------------------------------
| | | | | |
| | | | | |
2 4 6 8 10 12
Pin Description
=== ===========
1 Red analog video out (1v DC offset, 1vpp video into 75 ohms)
2 Green analog video out (1v DC offset, 1vpp video into 75 ohms)
3 Composite H/V sync out (1vpp into 75 ohms)
4 Blue analog video out (1v DC offset, 1vpp video into 75 ohms)
5 Ground
6 Ground
7 Y (luminance) signal for S-VHS (1vpp into 75 ohms)
8 C (chroma) signal for S-VHS (1vpp into 75 ohms)
9 NTSC composite video signal (1vpp into 75 ohms)
10 +5v (Could be just a high logic signal)
11 Left channel audio out
12 Right channel audio out
Additional Notes:
As seen above, the SNES does have RGB capability. I was able to get a
stable raster on my NEC MultiSync "classic" using the RGB and sync
pins. However, the video levels are not RS-170 compatible. The DC
offset needs to be filtered out with some large capacitors and the
peak-to-peak video amplitude may need to be reduced to 0.7v by using a
lower load impedance than 75 ohms. The Y/C (S-VHS) signals *appear* to
be directly usable, but tests cannot be made until I find the pinouts
for the S-VHS connector on my TV.
_________________________________________________________________
CHAPTER 4) SNES CONTROLLER CABLE CONNECTOR PINS.
I could not find a Nintendo numbering scheme, so I made one up. The
view is looking back "into" the connector on the CABLE.
----------------------------- ---------------------
| | \
| (1) (2) (3) (4) | (5) (6) (7) |
| | /
----------------------------- ---------------------
Pin Description Color of wire in cable
=== =========== ======================
1 +5v White
2 Data clock Yellow
3 Data latch Orange
4 Serial data Red
5 ? no wire
6 ? no wire
7 Ground Brown
Additional notes:
Pins 5 and 6 show a DC voltage of 5v on a DMM. I forgot to look at
them on a scope so there may pulses too. However, they don't connect
to anything at present.
The controllers have a small circuit board with 2 surface mount 14-pin
ICs, marked by Nintendo as IC-A and IC-B. Although rubber domes are
used to provide the tactile response of the buttons, they are not
capacitive technology as originally thought. Instead they use what
appears to be carbon impregnated rubber on the underside which makes a
resistive path (200 ohms) across 2 carbon coated PCB pads when
depressed.
* The red wire goes to pin 2 on IC-A.
* The orange wire goes to pin 8 on both IC-A and IC-B.
* The yellow wire goes to pin 9 on both IC-A and IC-B.
IC-A and IC-B appear to be identical, with a 91 date code and have
another (possible part number) of 545. These are most likely 2
parallel load shift registers in series. Buttons on the controller
pull the parallel load inputs to ground through the contact formed by
pressing a button. IC-B serially feeds IC-A, which then drives the
serial data line to the SNES CPU.
_________________________________________________________________
CHAPTER 5) SNES CONTROLLER COMMUNICATION PROTOCOL
Every 16.67ms (or about 60Hz), the SNES CPU sends out a 12us wide,
positive going data latch pulse on pin 3. This instructs the ICs in
the controller to latch the state of all buttons internally. Six
microsenconds after the fall of the data latch pulse, the CPU sends
out 16 data clock pulses on pin 2. These are 50% duty cycle with 12us
per full cycle. The controllers serially shift the latched button
states out pin 4 on every rising edge of the clock, and the CPU
samples the data on every falling edge.
Each button on the controller is assigned a specific id which
corresponds to the clock cycle during which that button's state will
be reported. The table in section 4.0 lists the ids for all buttons.
Note that multiple buttons may be depressed at any given moment. Also
note that a logic "high" on the serial data line means the button is
NOT depressed.
At the end of the 16 cycle sequence, the serial data line is driven
low until the next data latch pulse. The only slight deviation from
this protocol is apparent in the first clock cycle. Because the clock
is normally high, the first transition it makes after latch signal is
a high-to-low transition. Since data for the first button (B in this
case) will be latched on this transition, it's data must actually be
driven earlier. The SNES controllers drive data for the first button
at the falling edge of latch. Data for all other buttons is driven at
the rising edge of clock. Hopefully the following timing diagram will
serve to illustrate this. Only 4 of the 16 clock cycles are shown for
brevity.
|<------------16.67ms------------>|
12us
-->| |<--
--- ---
| | | |
Data Latch --- -----------------/ /---------- --------...
Data Clock ---------- - - - -/ /---------------- - ...
| | | | | | | | | | | |
- - - - - -
1 2 3 4 1 2
Serial Data ---- --- ----/ / ---
| | | | | |
(Buttons B --- --- --- ----------
& Select norm B SEL norm
pressed). low low
12us
-->| |<--
_________________________________________________________________
CHAPTER 6) SNES CONTROLLER BUTTON-TO-CLOCK PULSE ASSIGNMENT
Clock Cycle Button Reported
=========== ===============
1 B
2 Y
3 Select
4 Start
5 Up on joypad
6 Down on joypad
7 Left on joypad
8 Right on joypad
9 A
10 X
11 L
12 R
13 none (always high)
14 none (always high)
15 none (always high)
16 none (always high)
Additional notes:
Clock cycles 13-16 are essentially unused. It would be interesting to
see how the SNES responds if we drive low button data during these
cycles. Nintendo may use these for future controllers with more
capabilities.
(From the Editor)
NOTE: S-VHS is not means to mean Super-VHS. It stands for Super-Video
(connector and output)
#### Additional Info (From Kevin Horton)
OK, the SNES uses the 65816 processor, which is basically a 16-bit
version of the 6502. It runs at 3.579545 MHz (color-burst), and has an
8-bit data bus. It can address up to 16MB.
The carts are nothing more than ROM. To tell you how much data is one,
take the number of 'MegaBits' and divide by 8 to get megabytes. That's
how much data is really in the carts. So, an 8-mbit cart really is
only 1 megabyte.
https://cdn.preterhuman.net/texts/gaming_and_diversion/Video_and_Computer_Games/SNESPin.txt
Topic: SNES PINOUTS & PROTOCOL (Read 3509 times)
