I2C Bus

From DSiBrew
Revision as of 02:09, 16 July 2010 by Yellows8 (talk | contribs) (Created page with '== Registers == {| class="wikitable" border="1" ! NAME ! ADDRESS ! WIDTH |- | REG_I2CDATA | 0x04004500 | 1 |- | REG_I2CCNT | 0x04004501 | 1 |} == REG_I2CDATA == {| class="wik…')
(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)
Jump to navigation Jump to search

Registers

NAME ADDRESS WIDTH
REG_I2CDATA 0x04004500 1
REG_I2CCNT 0x04004501 1

REG_I2CDATA

BIT DESCRIPTION
0 R/W, clear for write, set for read
1 Start/device select bit?
2 Restart/device reselect bit?
3 ?
4 SCL hold. When clear SCL is being held low, set when SCL is high. This bit must always be set after writing REG_I2CCNT.
5 SCL, toggle this for each loop iteration(in the loop execute the I2C WR code) with max 8 iterations where the loop exits successfully when bit 4 is set.
6 Unknown, always set when writing to CNT?
7 Enable/busy

Protocol

Wait for the busy bit to clear. Write the device address to REG_I2CDATA, then write 0xc2(busy/enable, bit 6, and start bit 1 set) to REG_I2CCNT. Execute swiWaitByLoop for a device-specific duration, then write the register address to REG_I2CDATA, and write 0xc0 to REG_I2CCNT.(busy/enable and bit 6 set) Wait with swiWaitByLoop device duration, then write the data to REG_I2CDATA when writing. When reading, write the device address to REG_I2CDATA and write 0xc2 to REG_I2CCNT. When the delay value is zero, write 0xc1 | i<<5 to REG_I2CCNT, otherwise write 0xc0 | i<<5 to REG_I2CCNT, wait for busy to clear, delay, then write 0xc5 to REG_I2CCNT. For writing i is the loop i for iteration, for reading replace that with 1. When reading, read the data from REG_I2CCNT. Return a error if REG_I2CCNT bit 4 SCL hold is set, otherwise return normal.

I2C devices

Power management addr 0x4

When registers 0x70 and 0x11 are set to 1 in that order, a power cycle is done.

REGISTER DESCRIPTION
0x11 System reset register 2.
0x31 Camera related? Values can be 1 or 2. Probably either turns the cameras' power on/off, or sets which camera to use?(internal/external cameras.)
0x70 System reset register 1.