Datasheet
transferring in High-speed mode. The master code byte must contain data in the form of 0000.1XXX
and is used to tell the slave devices to prepare for a High-speed transfer. The master code byte
should never be acknowledged by a slave since it is only used to indicate that the upcoming data
is going to be transferred at a higher data rate. To send the master code byte for a standard
high-speed transfer, software should place the value of the master code byte into the I2CMSA
register and write the I2CMCS register with a value of 0x13. If a high-speed burst transfer is required,
then to send the master code byte, software should place the value of the master code byte into
the I2CMSA register and write the I2CMCS register with 0x50. Either configuration places the I
2
C
master peripheral in High-speed mode, and all subsequent transfers (until STOP) are carried out
at High-speed data rate using the normal I2CMCS command bits, without setting the HS bit in the
I2CMCS register. Again, setting the HS bit in the I2CMCS register is only necessary during the
master code byte.
When operating as a High-speed slave, there is no additional software required.
Figure 21-7. High-Speed Data Format
SDA
SCL
Device-Specific NAK Address
R/W
Data
Standard (100 KHz) or Fast Mode (400 KHz)
High Speed
(3.3 Mbps)
Note: High-Speed mode is 3.4 Mbps, provided correct system clock frequency is set and there is
appropriate pull strength on SCL and SDA lines.
21.3.3 Interrupts
The I
2
C can generate interrupts when the following conditions are observed in the Master Module:
■ Master transaction completed (RIS bit)
■ Master arbitration lost (ARBLOSTRIS bit)
■ Master Address/Data NACK (NACKRIS bit)
■ Master bus timeout (CLKRIS bit)
■ Next byte request (RIS bit)
■ Stop condition on bus detected (STOPRIS bit)
■ Start condition on bus detected (STARTRIS bit)
■ RX DMA interrupt pending (DMARXRIS bit)
■ TX DMA interrupt pending (DMATXRIS bit)
■ Trigger value for FIFO has been reached and a TX FIFO request interrupt is pending (TXRIS
bit)
■ Trigger value for FIFO has been reached and a RX FIFO request interrupt is pending (RXRIS
bit)
1435December 13, 2013
Texas Instruments-Advance Information
Tiva
™
TM4C129XNCZAD Microcontroller