Intel® PXA255 Processor Developer’s Manual 9-23

I2C Bus Interface Unit

on the acknowledge pulse in receiver mode. After the processor reads the IDBR, the ACK/NAK

Control bit is written and the Transfer Byte bit is written, al lowing the next b yte tra nsfer to proceed

to the I2C bus. The IDBR register is 0x00 after reset.

This is a read/wri te register. Ignore reads from reserved bit s. Write zeros to res erved bits.
9.9.3 I2C Control Register (ICR)

The processor uses the ICR, shown in Table 9- 10, to control the I2C unit.

This is a read/wri te register. Ignore reads from reserved bit s. Write zeros to res erved bits.

Table 9-9. IDBR Bit Definitions

Physical Address
4030_1688 I2C Data Buffer Register I2C Bus Interface Unit
Bit 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
reserved IDB
Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
31:8 — reserved
7:0 IDB I2C Data Buffer: Buffer for I2C bus send/receive data.

Table 9-10. ICR Bit Definitions (Sheet 1 of 3)

Physical Address
4030_1690 I2C Control Register I2C Bus Interface Unit
Bit 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
reserved
FM
UR
SADIE
ALDIE
SSDIE
BEIE
IRFIE
ITEIE
GCD
IUE
SCLE
MA
TB
ACKNAK
STOP
START
Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
31:16 — reserved
15 FM Fast Mode:
0 = 100 KBit/sec. operation
1 = 400 KBit/sec. operation
14 UR Unit Reset:
0 = No reset.
1 = Reset the I2C unit only.
13 SADIE
Slave Address Detected Interrupt Enable:
0 = Disable interrupt.
1 = Enables the I2C unit to interrupt the processor when it detects a slave address match or
general call address.
12 ALDIE Arbitration Loss Detected Interrupt Enable:
0 = Disable interrupt.
1 = Enables the I2C unit to interrupt the processor when it loses arbitration in master mode.
11 SSDIE
Slave STOP Detected Interrupt Enable:
0 = Disable interrupt.
1 = Enables the I2C unit to interrupt the processor when it detects a STOP condition in
slave mode.