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UM10601
All information provided in this document is subject to legal disclaimers.
© NXP B.V. 2012. All rights reserved.
Preliminary user manual
Rev. 1.0 — 7 November 2012
189 of 313
NXP Semiconductors
UM10601
Chapter 16: LPC800 I2C-bus interface
16.6.2 I2C Status register
The STAT register provides status flags and state information about all of the functions of
the I
2
C block. Some information in this register is read-only, some flags can be cleared by
writing a 1 to them.
Access to bits in this register varies. RO = Read-only, W1 = write 1 to clear.
Details on the master and slave states described in the MSTSTATE and SLVSTATE bits in
this register are listed in
and
Table 171. I
2
C Status register (STAT, address 0x4005 0004) bit description
Bit
Symbol
Value Description
Reset
value
Acce
ss
0
MSTPENDING
Master Pending. Indicates whether the Master function needs software
service. This flag will cause an interrupt when set if enabled via the
INTENSET register. The MSTPENDING flag is automatically cleared
when a 1 is written to the MSTCONTINUE bit in the MSTCTL register.
1
RO
0
No service needed. The Master function does not currently need service.
1
Service needed. The Master function needs service. Information on what
is needed can be found in the adjacent MSTSTATE field.
3:1
MSTSTATE
Master State code. Each value of this field indicates a specific required
service for the Master function. All other values are reserved.
0
RO
0x0
Idle. The Master function is available to be used for a new transaction.
0x1
Receive ready. Received data available (Master Receiver mode).
Address plus Read was previously sent and Acknowledged by slave.
0x2
Transmit ready. Data can be transmitted (Master Transmitter mode).
Address plus Write was previously sent and Acknowledged by slave.
0x3
Address. Slave Nacked address.
0x4
Data. Slave Nacked transmitted data.
4
MSTARBLOSS
Master Arbitration Loss flag. This flag can be cleared by software writing
a 1 to this bit. It is also cleared automatically a 1 is written to
MSTCONTINUE.
0
W1
0
No loss. No Arbitration Loss has occurred.
1
Arbitration loss. The Master function has experienced an Arbitration
Loss.
At this point, the Master function has already stopped driving the bus and
gone to an idle state. Software can respond by doing nothing, or by
sending a Start in order to attempt to gain control of the bus when it next
becomes idle.
5
-
Reserved. Read value is undefined, only zero should be written.
NA
NA
6
MSTSTSTPERR
Master Start/Stop Error flag. This flag can be cleared by software writing
a 1 to this bit. It is also cleared automatically a 1 is written to
MstContinue.
0
W1
0
No Start/Stop Error has occurred.
1
Start/stop error has occurred. The Master function has experienced a
Start/Stop Error.
A Start or Stop was detected at a time when it is not allowed by the I
2
C
specification. The Master interface has stopped driving the bus and gone
to an idle state, no action is required. A request for a Start could be
made, or software could attempt to insure that the bus has not stalled.