Datasheet

14.3.3 Interrupts
The I
2
C can generate interrupts when the following conditions are observed:
■ Master transaction completed
■ Master arbitration lost
■ Master transaction error
■ Slave transaction received
■ Slave transaction requested
There is a separate interrupt signal for the I
2
C master and I
2
C slave modules. While both modules
can generate interrupts for multiple conditions, only a single interrupt signal is sent to the interrupt
controller.
14.3.3.1 I
2
C Master Interrupts
The I
2
C master module generates an interrupt when a transaction completes (either transmit or
receive), when arbitration is lost, or when an error occurs during a transaction. To enable the I
2
C
master interrupt, software must set the IM bit in the I
2
C Master Interrupt Mask (I2CMIMR) register.
When an interrupt condition is met, software must check the ERROR and ARBLST bits in the I
2
C
Master Control/Status (I2CMCS) register to verify that an error didn't occur during the last transaction
and to ensure that arbitration has not been lost. An error condition is asserted if the last transaction
wasn't acknowledged by the slave. If an error is not detected and the master has not lost arbitration,
the application can proceed with the transfer. The interrupt is cleared by writing a 1 to the IC bit in
the I
2
C Master Interrupt Clear (I2CMICR) register.
If the application doesn't require the use of interrupts, the raw interrupt status is always visible via
the I
2
C Master Raw Interrupt Status (I2CMRIS) register.
14.3.3.2 I
2
C Slave Interrupts
The slave module can generate an interrupt when data has been received or requested. This interrupt
is enabled by writing a 1 to the DATAIM bit in the I
2
C Slave Interrupt Mask (I2CSIMR) register.
Software determines whether the module should write (transmit) or read (receive) data from the I
2
C
Slave Data (I2CSDR) register, by checking the RREQ and TREQ bits of the I
2
C Slave Control/Status
(I2CSCSR) register. If the slave module is in receive mode and the first byte of a transfer is received,
the FBR bit is set along with the RREQ bit. The interrupt is cleared by writing a 1 to the DATAIC bit
in the I
2
C Slave Interrupt Clear (I2CSICR) register.
If the application doesn't require the use of interrupts, the raw interrupt status is always visible via
the I
2
C Slave Raw Interrupt Status (I2CSRIS) register.
14.3.4 Loopback Operation
The I
2
C modules can be placed into an internal loopback mode for diagnostic or debug work. This
is accomplished by setting the LPBK bit in the I
2
C Master Configuration (I2CMCR) register. In
loopback mode, the SDA and SCL signals from the master and slave modules are tied together.
14.3.5 Command Sequence Flow Charts
This section details the steps required to perform the various I
2
C transfer types in both master and
slave mode.
519June 18, 2012
Texas Instruments-Production Data
Stellaris
®
LM3S8962 Microcontroller
NRND: Not recommended for new designs.