Hardware/SMC

General

The Wii U added a new chip to assist with power management alongside the RTC, labeled "SMC". The SMC is responsible for managing disc drive power/eject, power LED patterns, wireless resets, regulator enable/PGOOD monitoring, and possibly other unknown functionality. Known part numbers include 1224EE429 301, 1225EE423 301. Chip is a 78K0/KC2-L from NEC/Renesas.

Communication

SMC resides as device ID 0x50 on I2C bus 3. It communicates at 5kHz in IOS and 10KHz in Cafe2Wii?

Registers

SMC has two types of registers: Read/write and command-based. Read/write registers operate by having the register number written (1 byte), followed by either another written byte, or a 1 byte read. Command-based registers perform their action just by writing the register number (1 byte). When attempting to read a command-based register, it will read as 0xFF.

Index	Type	Description
0x00	Command	SMC_CMD_ODD_ON
0x01	Command	SMC_CMD_ODD_OFF
0x02	Command	SMC_CMD_ODD_EJECT
0x10	Command	SMC_CMD_SBYLED_OFF
0x11	Command	SMC_CMD_PWRLED_ON
0x12	Command	SMC_CMD_PWRLED_OFF
0x13	Command	SMC_CMD_PWRLED_BLINK
0x14	Command	SMC_CMD_C24LED_OFF
0x15	Command	SMC_CMD_C24LED_ON
0x16	Command	SMC_CMD_C24LED_BLINK
0x1E	Command	SMC_CMD_SBYLED_ON
0x1F	Command	SMC_CMD_SBYLED_BLINK
0x20	Command	SMC_CMD_RESET_BT
0x21	Command	SMC_CMD_RESET_WIFI24
0x22	Command	SMC_CMD_RESET_WIFI5
0x30	Read/Write	SMC_CMD_TIMER_23_16
0x31	Read/Write	SMC_CMD_TIMER_15_08
0x32	Read/Write	SMC_CMD_TIMER_07_00
0x40	Read	SMC_CMD_PROG_REVISION (val: 0xC5)
0x41	Read	SMC_CMD_SYSTEM_EVENT
0x42	Read	SMC_CMD_ODD_FLAG (val: 0x0B, 0x0A?)
0x43	Read/Write	SMC_CMD_USB_FLAG (bitmask; front USB: 0x1, rear USB: 0x2)
0x44	Read/Write	SMC_CMD_CCIND_FLAG
0x45	Read/Write	SMC_CMD_PWRERR_FLAG (val: 0x08)
0x46	Read/Write	SMC_CMD_DEVEN_FLAG (val: 0x00)
0x47	Read	? not writable (val: 0xFF)
0x48	Read	ChipRevision (val: 0x0F)
0x49	Read	? (val: 0x4000000; needs ProgramRevision > 0xD3?)
0x60~0x6F	Read/Write	Nvram
0x70	Read	UnkDataValid (0x01 when UnkData is valid, else 0x00)
0x71	Read/Write?	Blinks the drive LED/reset on read? (I2C reads 0xFF briefly).
0x72	Read/Write	Seems to affect whether UnkDataValid is set for addrs 0x4~0x81. bit1 fills in UnkData with 0x5, ((reg & 0xF0) > 0x80) returns UnkDataValid to 0? (val: 0x00)
0x73	Read/Write	UnkAddrHi? Changes to 0x10 when UnkAddrHi is less than 0x10. (val: 0x00)
0x74	Read/Write	UnkAddrLo? Changes UnkData and UnkDataValid. (val: 0x00)
0x75	Read	? (val: 0x00)
0x76	Read	UnkData. Changes to 0x5 then 0xf1 when 0x74 is written to 0x00 twice.
0x80~0xFF	Read/Write	scratch mem? (val: 0x00)

SMC_CMD_SYSTEM_EVENT

Bits	Description
0	SMC_WAKE1
1	SMC_WAKE0
2	SMC_BT_IRQ
3	SMC_TIMER
4	SMC_DISK_INSERT
5	SMC_EJECT_BUTTON
6	SMC_POWER_BUTTON
7

SMC_CMD_CCIND_FLAG

Bits	Description
0	Yellow LED pulse
1	Yellow LED on
2	Red LED pulse
3	Red LED on
4	Blue LED pulse
5	Blue LED on
6-7

SMC_CMD_DEVEN_FLAG

Bits	Description
0	SMC_DEVEN_WIFI24
1-7

Nvram

Must be written from largest to smallest address for values to be set.

Offset	Size	Description
0x0	0x1	LAPSSetting
0x1	0xF	SystemError

Pinout

Counter-clockwise from the dot and PCB arrow:

Pin number	Name	Notes
01	INTP0/EXLVI	Connects to TP146, RTC, WIFI24 (connector pin 21) and BT (connector pin 11). Input. Triggers blinking red LED on LOW.
02	RESET	Connects to TP145 and RTC. Resets SMC when measured. On WUP-DEV-X9, attached to a 5-pin header (pin1).
03	XT2/EXCLKS	Connects to TP144 and RTC. Input. SMC stops i2c on LOW.
04	XT1	Connects to TP168 and SW4 (pins 1 and 3).
05	IC	Disconnected (Internally Connected).
06	X2/EXCLK/TOOLD0	Disc presence sensor (receiver). Connects to TP19 and disc drive (connector pin 19). On WUP-DEV-X9, attached to a 5-pin header (pin2).
07	X1/TOOLC0	Clock (pulses between 3.3v and 0v at 1Hz). Connects to TP175 and RTC. On WUP-DEV-X9, attached to a 5-pin header (pin3).
08	REGC	Connected to GND via C137.
09	Vss
10	Vdd	Connects to decoupling cap C73.
11	P60/SCLA0	Connects to TP153. I2C SCL.
12	P61/SDAA0	Connects to TP154. I2C SDA.
13	P62	Connects to TP70 (separated by resistor). Power Button (active low).
14	P33	Connects to TP155.
15	P73/KR3	Rear USB enable. Connects to TP80.
16	P72/KR2	Rear USB fault. Connects to TP109.
17	P71/KR1	Connects to TP38.
18	P70/KR0	Connects to TP15.
19	P32	Connects to TP157.
20	P31	Front USB enable. Connects to TP39.
21	P30	Connects to TP68, and faceplate (connector pin 8, not connected to any buttons). Internal pull-up.
22	P17	Front USB power fault. Connects to TP95.
23	P16	Connects to TP156 and BT (connector pin 12).
24	P15	White LED. Transistor pin. PWM at 100Hz.
25	P14	Eject button. Connects to faceplate. Input, internal pull-up.
26	P13	Yellow LED. Connects to TP2001 and faceplate. PWM at 100Hz.
27	P12	Connects to TP37.
28	P11	Connects to TP171 and faceplate.
29	P10	Connects to TP16.
30	AVref	Connects to decoupling cap C73.
31	AVss
32	P26	Disc presence sensor (transmitter). Connects to TP18. 8Hz.
33	P25	Fake power button (connected to RTC, pulsed low with Eject). Connects to TP9.
34	P24	Disk eject (to drive, active high). Connects to TP5.
35	P23	Optical power enable? Connects to TP152, TP88 and battery.
36	P22	Connects to TP172 and BT (connector pin 13).
37	P21	Connects to TP173 and WIFI5 (connector pin 7).
38	P20	Connects to TP174 and WIFI24 (connector pin 16).
39	P01	Blue LED. Transistor lead. PWM at 100Hz.
40	P00	Red LED. Connects to TP66, TP2000 and faceplate. PWM at 100Hz.

WUP-DEV debug header

WUP-DEV-X9 has an unpopulated through-hole 5-pin debug header for SMC.

Pin number	Name	Notes
01	nRST	Connects to SMC RESET.
02	?	Connects to SMC TOOLD0 (data input/output for tool).
03	?	Connects to SMC TOOLC0 (clock input for tool).
04	3v3	Connects to TP122.
05	GND	Connects to GND.