DR
AFT
DR
AFT
DRAFT
DR
D
RAFT
DRAFT
DRA
FT DRAF
D
RAFT DRAFT DRAFT DRAFT DRAFT D
DRAFT
D
RAFT DRA
FT DRAFT DRAFT DRAFT DRA
UM10316_0
© NXP B.V. 2008. All rights reserved.
User manual
Rev. 00.06 — 17 December 2008
396 of 571
NXP Semiconductors
UM10316
Chapter 23: LPC2xx I2C-interface
STAC
is the Start flag Clear bit. Writing a 1 to this bit clears the STA bit in the I2CONSET
register. Writing 0 has no effect.
I
2ENC
is the I
2
C Interface Disable bit. Writing a 1 to this bit clears the I2EN bit in the
I2CONSET register. Writing 0 has no effect.
8.8 I
2
C Monitor mode control register (I2MMCTRL: I2C0, I2CMMCTRL0 -
0xE008 201C; I2C1, I2C1MMCTRL- 0xE008 301C)
This register controls the Monitor mode which allows the I
2
C module to monitor traffic on
the I
2
C bus without actually participating in traffic or interfering with the I
2
C bus.
[1]
When the ENA_SCL bit is cleared and the I2C no longer has the ability to stall the bus, interrupt response
time becomes important. To give the part more time to respond to an I2C interrupt under these conditions,
a DATA BUFFER register is used (
) to hold received data for a full 9-bit word transmission
time.
Table 331. I
2
C Monitor mode control register (I2MMCTRL: I2C0, I2CMMCTRL0 - 0xE008 201C;
I2C1, I2C1MMCTRL- 0xE008 301C) bit description
Bit Symbol
Value
Description
Reset value
0
MM_EN
A
Monitor mode enable.
0
0
Monitor mode disabled.
1
The I2C module will enter monitor mode. In this mode the
SDA output will be forced high. This will prevent the I2C
module from outputting data of any kind (including ACK)
onto the I2C data bus.
Depending on the state of the ENA_SCL bit, the output
may be also forced high, preventing the module from
having control over the I2C clock line.
1
ENA_SC
L
SCL output enable.
0
0
When this bit is cleared to ‘0’, the SCL output will be
forced high when the module is in monitor mode. As
described above, this will prevent the module from having
any control over the I2C clock line.
1
When this bit is set, the I2C module may exercise the
same control over the clock line that it would in normal
operation. This means that, acting as a slave peripheral,
the I2C module can “stretch” the clock line (hold it low)
until it has had time to respond to an I2C interrupt.
3
MATCH_
ALL
Select interrupt register match.
0
0
When this bit is cleared, an interrupt will only be
generated when a match occurs to one of the (up-to) four
address registers described above. That is, the module
will respond as a normal slave as far as
address-recognition is concerned.
1
When this bit is set to ‘1’ and the I2C is in monitor mode,
an interrupt will be generated on ANY address received.
This will enable the part to monitor all traffic on the bus.