Project Overview

Nintendo 64 and Gamecube controllers are excellent controllers which are quite appropriate for many PC games, and of course are perfect for emulators!. The microcontroller firmware in this projet implements a standard HID joystick which means that no special device driver is required. It works perfectly well under Linux and Windows.



Why?
One of my friends wanted to play Nintendo 64 games on his PC using an original controller... so I developped an adapter for doing this. But since Gamecube controllers use a very similar protocol, it was easy to support Gamecube controllers too.

Gamecube and Nintendo 64 controllers both work at 3.3 volts. But on the USB bus, only 5 volts are available. For this reason, a voltage regulator is required. Apart from the different firmware, this is the only difference (and additional complexity) this project has with my Nes/Snes controller to USB project.

Ready to use adapters available

Pictures

Adapter example

N64 or Gamecube to USB with regulator on-board:

Controller conversion

An example of permanently converting a N64 controller to USB. There is not much space inside, but by removing a small amount of plastic, the circuit fits well in the controller's middle "finger". The layout of the wires must be carefully planned in order not to interfere with the cover. I used hot glue to hold them in place.

Historic/Development pictures

Pictures of the printed circuit board with an lm1117 adjustable voltage regulator:

Pictures taken during development with the new PCB:

Pictures of the N64 to USB prototype. I used an lm317 adjustable voltage regulator:
The N64 Hori-mini and white Gamecube controller with extra long cable work!
The Gamecube keyboard is supported since version 2.9.

---

Contributions

Here are some pictures from Declan Williams (16 years old!):

---

Sean Green built and used my circuit in a few projects:
Note: The bliss 4pack displayed here is NOT a 4 player version of the project. It is only an USB HUB with 4 built-in GC/N64 to USB converters.

---

2013-02-14: Ludivine built a N64 adapter based on this project. The voltage regulator is on the back side of the PCB.

---

July 19, 2014 (Saturday)
TALENTO from Bulgaria sent me pictures of the GC/N64 to USB adapter he built on universal board.

---

October 5, 2014 (Sunday)
Browner87 used a 3D printer to build an enclosure housing a pair of GC/N64 to USB circuits, four controller connectors and an USB Hub. Additional comments and pictures available on imgur.

---

October 11, 2014 (Saturday)
Jonathan sent me the following pictures of the Gamecube to USB adapter he built. He used an Atmega8L-8PU which is therefore overclocked. But it seems to work fine for him.

---

March 10, 2015 (Tuesday)
Rickey sent me a picture of the adapter he build on a breadboard. He used an ATMega328P programmed with the Atmega168 firmware and fuses and everything works!

---

March 25, 2015 (Wednesday)
Ashley form Queensland, Australia, is helping his little brother Shaun (who's 14) with a few projects to get him interested in something other than just playing games. Together they built the SNES/NES to USB and Gamecube/N64 to USB circuit on a single breadboard. Components are on their way for the final version.

Schematics

Here are the schematics:

Comments: Some webpages mention that the Gamecube controllers work at 3.43 volts, some other pages says it's any voltage between 3.3 and 3.8! volts... I read an old message in the comp.emulators.game-consoles news group where the author said that the Nintendo 64 supplies 5 volts to the controllers (Wrong!). I measured 3.36 volts on my N64 so personally, I choose to supply 3.3 volts to my Gamecube and N64 controllers.

In order to obtain 3.3 volts, you can use a fixed voltage regulator such as the 78M33C or an adjustable voltage regulator such as the lm317 or lm1117 (exemple). If you use an lm317 variable voltage regulator, here's a simple tool which can help you find a good value for R1. Any voltage between 3.26 and 3.40 volts should do the job.

Adjustment resistor (R2): Fixed resistor (R1): Output voltage (Vout):

Note: The picture comes from motorola's lm317 datasheet: lm317rev1g.pdf

---

Wavebird color code (for reference only)
I have been informed that the color of the wires running from the gamecube connector to the PCB inside the receiver seem to be constant:

• +3.3v: Rouge
• Data: Green
• GND: Brown (Pin)
• GND: Violet (Shield)

Keep in mind that wire colors varies between manufactures, and sometimes between revisions of the same product. Blindly following color codes without any checks can be a good way to ruin electronics.

Printed Circuit Board

The PCB is an improved version of the PCB used for the Nes/Snes controller to USB.. This new PCB has a voltage regulator and reprogramming contacts on the bottom side. Here are composite images of the top and bottom layers:



The regulator is an lm1117mp-adj. 0 ohm resistors must be installed to select the power source (USB 5 volts or regulator output) for the microcontroller and the controller. In this case, R5 and R8 must be installed:


Here is a wiring diagram for the board:


And finally, here are the gerber files which you can use produce this PCB:
multiuse.zip

Due to the fact that this board is two-sided and has numerous vias, building it at home may be a little harder than the ususal. If you want, you can get professional PCBs from my online store. The PCBs from my store, however, are a little older than the one above. I've had a huge quantity produced with a small mistake: The 5 volts supply from the USB bus does not reach the regulator!

In order to correct this, a small wire has to be installed on the bottom side:

Fully assembled and programmed PCB(s) available

Firmware

Version v2.9.2 December 9, 2015 (Wednesday)
Fixed Wavebird detection (was unreliable since v2.9)
File(s): gc_n64_usb-2.9.2.tar.gz (474.4 KB) gc_n64_usb-m8-2.9.2.hex (19 KB) gc_n64_usb-m168-2.9.2.hex (19.7 KB)

Source code:
The source code is available under the GPLv2 license. See License.txt for more information. The project compiles with avr-gcc.

Using the .hex files
Hexfiles in the gc_n64_usb-m8-x.x.hex format are for Atmega8, files in the gc_n64_usb-m168-x.x.hex format are for Atmega168. (Note: I'm told that the mega168 firmware and fuse vales also work for Atmega328p)

The fuses settings for this projet are:

• For Atmega8: high_byte=0xc9 low_byte=0x9f.
• For Atmega168: HFUSE = 0xD5, LFUSE = 0xD7, EFUSE = 0x01.

For details about how to program an AVR, please visit my AVR programming page.

pre-programmed Atmega8 DIP chips available

Hori-mini support

Since firmware version 1.3, all Hori-mini N64 pads are expected to work correctly thanks to a new algorithm which is tolerant to timing. A technical explaination of the issue and solution is given below.

Hori-mini N64 pads are known to misbehave with many adaptors. After testing a donated Hori-mini N64 pad with one of my adapters, they seemed to work properly... Until someone reported problems. When moving the axis, there would be sudden jumps to other positions, hindering gameplay. I tried my Hori controller with a few of my adapters and on a few computers. I eventually managed to find a unit which did not work well with my controller and began looking for the cause.

I noticed something unusual as soon as I looked at the communication between the Hori and my adapter. The Hori communication timing was very different from what I expected. The image below shows the low/high ratios for each bit being very different between the poll (from the adapter) and the answer (from the controller). The HORI controller replies at 66% the speed of a 'normal' N64 controller:

As you may already know, the bits are encoded as follows. Normally (at least with Nintendo's hardware), the timing is 3μs low/1μS high or 1μS low/3μS high for transmitting a 0 or 1 respectively. (See references for more information).

Normal timing Good: Sample centered

Hori timing Bad: Sample near rising edge

Why sampling near the rising edge is a problem:

• The sampling cannot be done exactly at 2μS. There is some jitter introduced by the polling loop used to detect the falling edge. In other words, some samples will be taken even closer to the rising edge, or during the rising edge.
• The Hori-mini PAD internal oscillator frequency may vary between units and with temperature. In other words, some controllers may send bits at a slightly slower rate (does not help) or faster (helps).
• The relatively slow-rising of the data line may also hinder reliability. At what point exactly will the MCU see a logic 1? This is in the MCU specs, but it may change slighly from unit to unit or with newer version of the chip (e.g. Atmega8a) And if an extension cable increases capacitance, the situation will be worst.

The solution: (since version 1.3)
I concluded that I needed a better reception algorithm. Instead of sampling a little later or writing a new version that would measure the timing and adjust the sample position accordingly, I came up with something much better which will tolerate faster and much slower timings within a good margin:

1. Measure the time until rising edge (low level duration)
2. Measure the time until falling edge (high level duration)
3. Compare time spent low vs. high, if more time was spent low, we got a 0. Otherwise, we got a 1.
4. Repeat

Counting is done in assembler to be fast and predicatable (i.e. no C compiler optimisations in the way). At 16mhz, each polling cycle takes around 312.5nS. This means a 1μS level will count as 3 cycles and a 3μS will count as 9 cycles. If the timing is slower, the number of cycles will be greater, but the time spent low vs. time spent high relation will still apply.

USB Sync.

Since release 1.4, controller polling is synchronized with USB polls. The helps maintain accurate timing during communication with the controllers. It is hoped this will increase the (already quite good) compatibility and reliability of the circuit. Technocal explaination follows.

Remember the USB implementation is all software. The MCU can therefore be interrupted at any moment to take care of USB communications. Occasionally, this happens right when we are in the middle of communication with the game controller, messing with the timing. This is demonstrated on the picture on the right. Red marks a pause in the transmission (top waveform) because of USB communication (bottom waveform).

When an USB interrupt occurs at the wrong moment, the gamecube/n64 protocol frame is potentially corrupted and if it is, it should be discarded. When trasmitting, we rely on the game controller to detect the error and drop the frame. Then we simply timeout waiting for the answer. If instead the interrupt occrurs during reception, we will miss some transitions and won't receive the number of bits we expected.

Despite of the above theory, it would seem that occasionally (once in several minutes) some errors are not detected. A few users had reported that from time to time buttons seem to be reported active for a brief moment (even though hey were not pressed) so I decided to eliminate this risk by preventing these interrupts from occuring at the wrong time. And indeed, with the new white Gamecube controllers, the only controller I could confirm the problem with, the problem appears to be gone.

Disabling interrupts during the timing sensitive communication is not possible due to the software USB implementation that does not allow us to disable them for long enough a time to be useful. On the other hand, we have approximately 900μS between interrupts which leaves us enough of time to communicate with the controller without being disturbed. We just need to synchronize with the USB interrupts and poll the controller when USB is idle.

I thought of a very simple software solution. The logic which controls the controller polling rate stays the same. But just before the actual communication, the MCU is put in a sleep mode (IDLE mode). In this mode, normal execution stops until an interrupt occurs. When the execution resumes, we know an interrupt has occured and has been serviced so we can just continue and poll the controller. A small delay before polling helps us for cases where we receive a few interrupts in a burst.

With this solution implemented, the controller polling is always well placed inside the 900μS slot available between USB interrupts, as can be seen in the following screenshot:

L/R sliders calibration fixer

The Gamecube controller sliders are often problematic because they lack a central resting position. Many games assume an axis to be active when the value it reads is different, within a certain margin, from the center position. Thus, when performing button assignments, the L and R sliders will often immediately register as active and hinder (or most likely, prevent) successfully configuring the game for the controller.

The following tool must be run after performing calibration (standard windows tools) . When it is run, it looks for raphnet GC/N64 to usb adapters and alters the calibration data the system keeps for each unit found. All axis are left as calibrated, except the L and R sliders which are recentered.

The tool can be downloaded right here:
gc_calfix_ng_v1.3.zip Supports all firmware versions.

A successfull operation will output something like this:


Previous versions:
gc_calfix_ng_v1.2.zip Supports up to firmware version 2.3.

Keyboard support

Since firmware version 2.9, the Gamecube keyboard is supported and can be used under Windows and Linux. Note that I only tested ASCII model ASC-1901P0. This keyboard has a dual-connector cable. The gray connector is for the keyboard function and the purple one for the Joystick function. To use both functionalities simultaneously with a PC, two adapters are required.

Here are a few pictures of the keyboard:

Development log and technical details

November 23, 2013

The first thing I did was looking at what would be the answer to command 0x00 (GET ID). The adapter already uses this to detect the type of controller (N64 vs. GC) currently connected, so detecting the keyboard here was logical. I decoded the answer manually with a scope (much easier than for the Dreamcast controller communication protocol I was looking at recently...)

	0000 1000 0010 0000 0000 0000 : 0x082000

Note: Only the first 16 bits are used for ID. So the keyboard ID is in fact 0x0820.

Shortly after, I looked at a good gamecube documentation^[1] and confirmed I was getting the correct ID code, everything fine. I then continued experimenting and tried polling the keyboard using the command normally used to read the state of a controller (0x400300) but the keyboard did not answer. Not the right command. Back to the documentation, I learned comand 0x540000 should be used. Then of course, it worked.

The keyboard returns 64 bits (8 bytes):

First 32-bit word	Second word:
Bit 31: Errstat	Bits 31-24: Keycode (1)
Bit 30: Errlatch
Bits 29-28: ?
Bits 27-24: Looks like a 4-bit counter. Purpose unknown.
Bits 23-0: ?	Bits 23-16: Keycode (2)
	Bits 15-8: Keycode (3)
	Bits 7: ?
	Bits 6-4: Maybe a checksum. Depends on the depressed button combinations.
	Bits 3-0: Looks like a 4-bit counter. Purpose unknown.

This keyboard suports up to 3 simultaneous keypresses so I built the HID report descriptor accordingly. Usually, "special" keys such as CTRL, SHIFT and ALT are transmitted using dedicated bits in the report, but since the Gamecube keyboard does not have this concept and simply reports those keys like others (using full 8-bit keycodes), I do the same.

Unlike Dreamcast keyboards, this Gamecube keyboard does not use the keycodes from the USB HID Usage Tables document. (section 10 : Keyboard/Keypad page [0x07])

So I created a translation table. As this is a Japanese style keyboard, there are a few unusual keys and many won't produce the labelled characters unless the PC is configured to use a Japanese Keyboard.

Gamecube Name(s)	Gamecube KeyCode(s)	HID Name(s)	HID KeyCode(s)	Comments
A - Z	0x10 - 0x29	A - Z	0x04 - 0x1D
1 - 9	0x2A - 0x32	1 - 9	0x1E - 0x26
0	0x33	0	0x27
ESC	0x4C	ESC	0x29
BACKSPACE	0x50	BACKSPACE	0x2A
TAB		TAB	0x2B
SPACE		SPACE	0x2C
_=	0x34	-_	0x2D	First key right of 0
^~	0x35	=+	0x2E	Second key right of 0
@`	0x37	[{	0x2f	First key right of P
[{	0x38	]}	0x30	Second key right of P
]}	0x3B	Non-US # and ~	0x32	Third key right of L
;+	0x39	;:	0x33	First key right of L
:*	0x3A	'"	0x34	Second key right of L
半角・全角	0x3F	`~	0x35
,<	0x3C	,<	0x36
.>	0x3D	,>	0x37
/?	0x3E	/?	0x38
Caps lock・英数	0x53	Caps lock	0x39
F1 - F12	0x40 - 0x4B	F1 - F12	0x3A - 0x46
Scroll lock	0x0A	Scroll lock	0x47	Accessible via FN
Insert	0x4d	Insert	0x49
Home	0x06	Home	0x4A	Accessible via FN
PgUp	0x08	PgUp	0x4B	Accessible via FN
Delete	0x4E	Delete	0x4C
End	0x07	End	0x4D	Accessible via FN
PgDn	0x09	PgDn	0x4E	Accessible via FN
Right(→)	0x5F	RightArrow	0x4F
Left(←)	0x5C	LeftArrow	0x50
Down(↓)	0x5D	DownArrow	0x51
Up(↑)	0x5E	UpArrow	0x52
Enter	0x61	Enter	0x58
\_	0x3F	International 1	0x87	Extra key after /? [HID usage tables Footnote 15-20]
カタカナ・ひらがな	0x5B	International 2	0x88
¥|	0x36	International 3	0x89	Extra key before "back-space"
全候補・変換（次候補）	0x5A	International 4	0x8A
無変換	0x58	International 5	0x8B
CTRL (left)	0x56	Left control	0xE0
SHIFT (left)	0x54	Left shift	0xE1
SHIFT (right)	0x55	Right shift	0xE5
ALT (left)	0x57	Right alt	0xE6	Actually a LEFT-ALT key on the keyboard, but RIGHT-ALT is required to access alternate key functions 漢字、漢字番号、全候補 and ローマ字.

---

References:
^[1] Joy-Bus Devices, section 9.1, ID and Device List
^[2] Joy-Bus Devices, secion 9.3.2, Scancodes

DK Bongos support

The DK Bongos act like a standard controller so the adapter supports them without complications.

Bongo elements	Controller equivalent
Left pad (center)	Y
Left pad (front)	B
Right pad (centre)	X
Right pad (front)	A
Start button	Start
Microphone	R, varies with sound intensity.

References

Technical informations concerning Nintendo 64 controllers:
http://www.mixdown.ca/n64dev/

Technical information concerning the Gamecube controllers:
http://www.int03.co.uk/crema/hardware/gamecube/gc-control.htm

The N64 controller pinout appears on the following pages:
http://www.hardwarebook.info/N64_Controller
http://www.fpga-games.com/n64tst.htm

Disclaimer

I cannot be held responsible for any damages that could occur to you or your equipment while following the procedures present on this page. Also, I GIVE ABSOLUTELY NO WARRANTY on the correctness and usability of the informations on this page. Please note, however, that the procedures above have worked in my case without any damages or problems.

Now you cannot say that I did not warn you :)