Registers
| Old3DS
|
Name
|
Address
|
Width
|
Used by
|
| Yes
|
I2C1_DATA
|
0x10161000
|
1
|
|
| Yes
|
I2C1_CNT
|
0x10161001
|
1
|
|
| Yes
|
I2C1_CNTEX
|
0x10161002
|
2
|
|
| Yes
|
I2C1_SCL
|
0x10161004
|
2
|
|
| Yes
|
I2C2_DATA
|
0x10144000
|
1
|
|
| Yes
|
I2C2_CNT
|
0x10144001
|
1
|
|
| Yes
|
I2C2_CNTEX
|
0x10144002
|
2
|
|
| Yes
|
I2C2_SCL
|
0x10144004
|
2
|
|
| Yes
|
I2C3_DATA
|
0x10148000
|
1
|
|
| Yes
|
I2C3_CNT
|
0x10148001
|
1
|
|
| Yes
|
I2C3_CNTEX
|
0x10148002
|
2
|
|
| Yes
|
I2C3_SCL
|
0x10148004
|
2
|
|
I2C_CNT
| BIT
|
DESCRIPTION
|
| 0
|
Stop (0=No, 1=Stop/last byte)
|
| 1
|
Start (0=No, 1=Start/first byte)
|
| 2
|
Pause (0=Transfer Data, 1=Pause after Error, used with/after Stop)
|
| 4
|
Ack Flag (0=Error, 1=Okay) (For DataRead: W, for DataWrite: R)
|
| 5
|
Data Direction (0=Write, 1=Read)
|
| 6
|
Interrupt Enable (0=Disable, 1=Enable)
|
| 7
|
Start/busy (0=Ready, 1=Start/busy)
|
I2C Devices
| Device id
|
Device bus id
|
Device address
|
Device description
|
| 0
|
1
|
0x4a
|
Power management?(same device addr as the DSi power-management)
|
| 1
|
1
|
0x7a
|
Camera0?(same dev-addr as DSi cam0)
|
| 2
|
1
|
0x78
|
Camera1?(same dev-addr as DSi cam1)
|
| 3
|
2
|
0x4a
|
MCU
|
| 4
|
2
|
0x78
|
?
|
| 5
|
2
|
0x2c
|
?
|
| 6
|
2
|
0x2e
|
?
|
| 7
|
2
|
0x40
|
?
|
| 8
|
2
|
0x44
|
?
|
| 9
|
3
|
0xa6
|
Unknown. The device table in I2C-module had the device address changed from 0xA6 to 0xD6 with 8.0.0-18.
|
| 10
|
3
|
0xd0
|
Gyroscope
|
| 11
|
3
|
0xd2
|
?
|
| 12
|
3
|
0xa4
|
DebugPad
|
| 13
|
3
|
0x9a
|
IR
|
| 14
|
3
|
0xa0
|
eeprom?
|
| 15
|
2
|
0xee
|
New3DS NFC
|
| 16
|
1
|
0x40
|
?
|
| 17
|
3
|
0x54
|
Used by IR-module starting with 8.0.0-18, for New3DS HID via "ir:rst". This deviceid doesn't seem to be supported by i2c module on 8.0.0-18(actual support was later added in New3DS i2c module).
|
Device 3
| REGISTER
|
WIDTH
|
DESCRIPTION
|
| 0x03
|
8
|
?
|
| 0x04
|
8
|
?
|
| 0x09
|
1
|
Sound volume: 0x0..0x3F.
|
| 0xB
|
1
|
Battery level: 0x0..0x40.
|
| 0x18
|
8
|
?
|
| 0x20
|
8
|
Writing u8 value 4 here triggers a hardware system reboot. Writing u8 value 1 (repeatedly) triggers a shutdown via power-off?
|
| 0x22
|
8
|
?
|
| 0x23
|
8
|
?
|
| 0x24
|
8
|
?
|
| 0x28
|
8
|
?
|
| 0x29
|
8
|
?
|
| 0x2A
|
8
|
?
|
| 0x2B
|
8
|
?
|
| 0x2C
|
8
|
?
|
| 0x2D
|
0x64
|
This is used for controlling the notification LED(see MCURTC:SetInfoLEDPatternHeader as well), when this register is written.
|
| 0x2E
|
1
|
This returns the notification LED status when read.
|
| 0x30
|
8
|
?
|
| 0x31
|
8
|
?
|
| 0x32
|
8
|
?
|
| 0x33
|
8
|
?
|
| 0x34
|
8
|
?
|
| 0x35
|
8
|
?
|
| 0x36
|
8
|
?
|
| 0x37
|
8
|
?
|
| 0x38
|
8
|
?
|
| 0x39
|
8
|
?
|
| 0x3A
|
8
|
?
|
| 0x3B
|
8
|
?
|
| 0x3C
|
8
|
?
|
| 0x41
|
8
|
?
|
| 0x43
|
8
|
?
|
| 0x4E
|
8
|
?
|
| 0x50
|
8
|
?
|
| 0x51
|
8
|
?
|
| 0x58
|
8
|
?
|
| 0x60
|
8
|
?
|
Device 10
See the datasheet linked to on the Hardware page for reference.
Device 12
| REGISTER
|
WIDTH
|
DESCRIPTION
|
| 0x0
|
21
|
DebugPad state.
|
This is the DebugPad device, see here.
Device 13
| Raw I2C register address
|
Internal register address
|
Width
|
Description
|
| 0x0
|
0x0
|
0x40
|
RHR / THR (data receive/send FIFO)
|
| 0x8
|
0x1
|
0x1
|
IER
|
| 0x10
|
0x2
|
0x1
|
FCR/IIR
|
| 0x18
|
0x3
|
0x1
|
LCR
|
| 0x20
|
0x4
|
0x1
|
MCR
|
| 0x28
|
0x5
|
0x1
|
LSR
|
| 0x30
|
0x6
|
0x1
|
MSR/TCR
|
| 0x38
|
0x7
|
0x1
|
SPR/TLR
|
| 0x40
|
0x8
|
0x1
|
TXLVL
|
| 0x48
|
0x9
|
0x1
|
RXLVL
|
| 0x50
|
0xA
|
0x1
|
IODir
|
| 0x58
|
0xB
|
0x1
|
IOState
|
| 0x60
|
0xC
|
0x1
|
IoIntEna
|
| 0x68
|
0xD
|
0x1
|
reserved
|
| 0x70
|
0xE
|
0x1
|
IOControl
|
| 0x78
|
0xF
|
0x1
|
EFCR
|
See the datasheet linked to on the Hardware page for reference. From that datasheet, for the structure of the I2C register address u8: "Bit 0 is not used, bits 2:1 select the channel, bits 6:3 select one of the UART internal registers. Bit 7 is not used with the I2C-bus interface, but it is used by the SPI interface to indicate a read or a write operation."