Registers

NAME PHYSICAL ADDRESS PROCESS ADDRESS WIDTH
REG_I2C1DATA 0x10161000 0x1EC61000 1
REG_I2C1CNT 0x10161001 0x1EC61001 1
REG_I2C1CNTEX 0x10161002 0x1EC61002 2
REG_I2C1SCL 0x10161004 0x1EC61004 2
REG_I2C2DATA 0x10144000 0x1EC44000 1
REG_I2C2CNT 0x10144001 0x1EC44001 1
REG_I2C2CNTEX 0x10144002 0x1EC44002 2
REG_I2C2SCL 0x10144004 0x1EC44004 2
REG_I2C3DATA 0x10148000 0x1EC48000 1
REG_I2C3CNT 0x10148001 0x1EC48001 1
REG_I2C3CNTEX 0x10148002 0x1EC48002 2
REG_I2C3SCL 0x10148004 0x1EC48004 2

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 ?
10 3 0xd0 Gyroscope
11 3 0xd2 ?
12 3 0xa4 DebugPad
13 3 0x9a IR
14 3 0xa0 eeprom?
17 ? ? Used by IR-module starting with 8.0.0-18.

Device 3

REGISTER WIDTH DESCRIPTION
0x03 8 ?
0x04 8 ?
0x09 1 Sound volume: 0x0..0x3F.
0x18 8 ?
0x20 8 Writing u8 value 4 here triggers a hardware system reboot. Writing u8 value 8 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."

I2CCNT

REG_I2CxCNT
BIT DESCRIPTION
0 HOLD (0=Last byte of transaction, 1=More bytes coming)
2 Error flag/ack?
4 Read mode related?
5 Read mode?
6 IRQ enable?
7 Enable?