Pinouts

CTR CPU B

G

0?

CS1

?

?

D5

D2

RST

CLK

G

G

X

X

3v3

3v3

3v3

?

?

?

IRIRQ

?

?

G

1?

2?

CSx

CSy

?

D6

D3

D0

IRQ

CS1

G

G

G

G

3v3

3v3

G

?

?

?

?

?

?

3?

?

?

3v3

D7

D4

D1

DET

CS2

G

G

G

3v3

3v3

G

3v3

3v3

3v3

?

?

?

?

?

IRTX

?

?

?

CLK

D0

G

1v2

3v3

G

1v2

3v3

G

1v2

G

G

1v2

3v3

G

1v2

3v3

G

1v2

3v3

G

1v2

3v3

G

?

?

?

D1

D2

D3

3v3

1v2

?

?

?

CMD

IRQ

WP

1v2

1v8

?

?

?

CLK

D0

G

3v3

G

3v3

G

1v2

G

3v3

G

1v2

G

3v3

G

1v2

G

3v3

G

G

?

?

?

D1

D2

D3

3v3

G

3v3

G

3v3

G

3v3

G

3v3

G

3v3

G

3v3

G

3v3

G

1v2

1v2

?

?

?

CMD

1v2

1v2

G

1v2

G

1v8

?

?

?

?

?

?

G

G

3v3

G

1v8

G

?

?

?

?

?

3v3

3v3

G

1v2

G

1v2

?

?

?

1v2

G

3v3

G

1v8

1v8

?

?

?

G

1v2

G

1v8

G

G

?

?

?

SCL

3v3

G

3v3

G

1v2

1v2

?

?

?

SDA

1v2

3v3

G

1v8

G

1v8

?

?

?

?

?

G

G

1v2

G

1v8

G

?

?

?

?

?

1v8

1v2

G

1v8

G

1v2

?

?

?

?

?

1v2

G

1v8

G

1v2

1v8

?

?

?

?

?

?

G

1v8

G

1v8

G

G

?

?

?

?

?

?

1v8

G

1v8

G

1v8

1v2

?

?

?

G

?

?

1v2

1v2

G

1v8

G

1v8

G

1v8

G

1v2

G

1v8

G

1v8

G

1v8

G

1v8

?

?

?

?

?

?

G

G

1v8

G

1v2

G

1v8

G

1v2

G

1v8

G

1v2

G

1v8

G

1v2

G

?

?

?

?

?

?

1v8

1v2

?

?

?

?

?

?

1v2

1v8

?

?

?

?

?

?

G

1v8

1v2

G

1v8

1v2

G

1v8

1v2

G

1v8

1v2

G

1v8

1v2

G

1v8

1v2

G

1v8

1v2

G

?

?

?

?

?

?

?

?

?

?

?

?

?

3?

4?

5?

B

PADR

PADD

G

?

?

G

?

?

?

?

?

?

?

?

G

G

?

?

?

?

?

?

?

?

SDA

1?

2?

A

STRT

PADU

L

Y

?

?

?

?

?

?

?

G

?

?

?

?

?

?

?

?

SCL

0?

SLCT

PADL

R

X

?

?

?

?

?

?

G

legend:

SoC clock crystal

RTC clock crystal

Gamecard

SDCARD SDIO

NAND SDIO

WIFI SDIO

SPI

I2C-1

I2C-2

I2C-3

Pad

FCRAM

Camera

WIFI

GPIO

LCD0 (small)

LCD1 (big)

CODEC0 (unknown)

CODEC1 (unknown)

MCU (unknown)

POWER

Ground

Orientation: Triangle bottom right on the PCB.

UC CTR

This MCU seems to be a customized 64 pin FLGA version of this: https://www.renesas.com/ko-kr/doc/products/mpumcu/doc/rl78/r01ds0053ej0330-rl78g14.pdf

The pin layouts are similar, but not the same

Orientation: Pin 1 marker in bottom left corner

Hardware pins

+	G			TP75	X	X	?
SCL		G		/RESET	?	?	+
SDA		+	TP77	TP76			+
?		TP78	PWRLED1				CHRGLED
						G	G
	PWRBTN					BATTTHM
			PWRLED0			HOMEBTN
+				SCL	SDA		G

Software pins

Port ID	Pin ID	Purpose
043	??	Charging LED(?)
076	??	External IRQ (MCU --> SoC)

CODEC

	4?	3v3		3?	0?	?	?		G
	3?	5?	G		1?	CSx	?		G
G	2?	0?	G		2?	CSy				SPEAKER1
TOUCH	TOUCH	1?	G	G	G	G	G	G		SPEAKER1
TOUCH	TOUCH		G	G	G	G	G	G
CPAD	CPAD		G	G	G	G	G	G
			G	G	G	G	G	G		SPEAKER2
MIC		G	G	G	G	G	G	G		SPEAKER2
JACK_R	G	G		G						G
3v3				G	G	G	G
		G				JACK_L		G	G

LCD (old3DS bottom)

Pin number	Name	Description
01	-6V
02	12V
03	CLK	Pixel clock
04	/HBL	Horizontal blank (low while blanking)
05	/VBL	Vertical blank (low while blanking)
06	2v2	Loopback of pin 07?
07	2v2	Content latch? Shorting this to ground or to pin 06 will "lock" the screen memory while still allowing the screen to refresh itself.
08	GND	"chassi" ground
09	HCL	Horizontal clock
10	GND	"chassi" ground
11	BIAS 1	Default ~ 4.5V - 4.8V; sets contrast
12	BIAS 2	Usually matches BIAS 1; sets "flicker"
13	???	Might be a transistor? Shorted to ground if off, 2.36V if on.
14	6V
15	???	Loopback of pin 14 ? Shorting this with pin 14 or ground will make the 3DS turn off with a harsh pop sound.
16	???	???
17	???	???
18 [...] 25	RED 0 [...] RED 7	Red pixel bits
26	GND	"chassi" ground
27 [...] 34	BLUE 7 [...] BLUE 0	Blue pixel bits
35	GND	"chassi" ground
36 [...] 43	GREEN 7 [...] GREEN 0	Green pixel bits