UM10503
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© NXP B.V. 2012. All rights reserved.
User manual
Rev. 1.3 — 6 July 2012
1115 of 1269
NXP Semiconductors
UM10503
Chapter 43: LPC43xx I2C-bus interface
43.7.2 I
2
C Status register
Each I
2
C Status register reflects the condition of the corresponding I
2
C interface. The I
2
C
Status register is Read-Only.
The three least significant bits are always 0. Taken as a byte, the status register contents
represent a status code. There are 26 possible status codes. When the status code is
0xF8, there is no relevant information available and the SI bit is not set. All other 25 status
codes correspond to defined I
2
C states. When any of these states entered, the SI bit will
be set. For a complete list of status codes, refer to tables from
.
43.7.3 I
2
C Data register
This register contains the data to be transmitted or the data just received. The CPU can
read and write to this register only while it is not in the process of shifting a byte, when the
SI bit is set. Data in DAT remains stable as long as the SI bit is set. Data in DAT is always
shifted from right to left: the first bit to be transmitted is the MSB (bit 7), and after a byte
has been received, the first bit of received data is located at the MSB of DAT.
43.7.4 I
2
C Slave Address register 0
This register is readable and writable and are only used when an I
2
C interface is set to
slave mode. In master mode, this register has no effect. The LSB of ADR is the General
Call bit. When this bit is set, the General Call address (0x00) is recognized.
If this register contains 0x00, the I
2
C will not acknowledge any address on the bus. This
register will be cleared to this disabled state on reset. See also
Table 983. I
2
C Status register (STAT - address 0x400A 1004 (I2C0) and 0x400E 0004 (I2C1))
bit description
Bit
Symbol
Description
Reset value
2:0
-
These bits are unused and are always 0.
0
7:3
Status
These bits give the actual status information about the I
2
C
interface.
0x1F
31:8
-
Reserved. The value read from a reserved bit is not defined.
-
Table 984. I
2
C Data register (DAT - 0x400A 1008 (I2C0) and 0x400E 0008 (I2C1)) bit
description
Bit
Symbol
Description
Reset value
7:0
Data
This register holds data values that have been received or are
to be transmitted.
0
31:8
-
Reserved. The value read from a reserved bit is not defined.
-
Table 985. I
2
C Slave Address register 0 (ADR0 - address 0x400A 100C (I2C0) and
0x400E 000C (I2C1)) bit description
Bit
Symbol
Description
Reset value
0
GC
General Call enable bit.
0
7:1
Address
The I
2
C device address for slave mode.
0x00
31:8
-
Reserved. The value read from a reserved bit is not defined.
-