I2C Control Registers
1794
SPNU563A – March 2018
Copyright © 2018, Texas Instruments Incorporated
Inter-Integrated Circuit (I2C) Module
31.6.12 I2C Extended Mode Register (I2CEMDR)
The I2C extended mode register is a 16-bit memory-mapped register that contains additional mode select
bits.
and
describe this register.
Figure 31-25. I2C Extended Mode Register (I2CEMDR) [offset = 2Ch]
15
2
1
0
Reserved
IGNACK
BCM
R-0
R/W-0
R/W-1
LEGEND: R/W = Read/Write; R = Read only; -
n
= value after reset
Table 31-21. I2C Extended Mode Register (I2CEMDR) Field Descriptions
Bit
Field
Value
Description
15-2
Reserved
0
Reads return 0. Writes have no effect.
1
IGNACK
Ignore NACK mode.
0
The master transmitter will operate normally, discontinue the data transfer, and set the ARDY and
NACK status bits when a NACK signal is received from the slave.
1
The master transmitter will ignore a NACK received from the slave.
0
BCM
Backwards compatibility mode.
When set to 1, the I2C is compatible with previous versions of the I2C. This means the TXRDY interrupt
is generated in slave-transmit mode when TXRDY is set and the I2C needs more data to transmit. This
behavior causes an extra TXRDY interrupt to be generated because the I2C recognizes the end of
transfer after generating an interrupt for the next byte of data.
When BCM is 0, the TXRDY interrupt in slave-transmit mode is generated when XSMT = 1. In this case,
the I2C generates an interrupt for the next byte after receiving the ACK from previous data. The setting
of this bit only applies to slave transmit mode.
0
The I2C is not in compatibility mode.
1
The I2C is in compatibility mode.
31.6.13 I2C Prescale Register (I2CPSC)
The I2C prescaler register is a 16-bit memory-mapped register used for dividing down the VBUS_CLK to
obtain a module clock frequency between 6.7 MHz and 13.3 MHz.
and
describe
this register.
Figure 31-26. I2C Prescale Register (I2CPSC) [offset = 30h]
15
8
7
0
Reserved
PSC
R-0
R/W-0
LEGEND: R/W = Read/Write; R = Read only; -
n
= value after reset
Table 31-22. I2C Prescale Register (I2CPSC) Field Descriptions
Bit
Field
Value
Description
15-8
Reserved
0
Reads return 0. Writes have no effect.
7-0
PSC
0-FFh
Prescale
8-bit prescaler to divide down the VBUS clock to obtain the I2C module clock. This register must
be initialized while the I2C is still in reset (nIRS = 0). The value takes effect on the rising edge of
nIRS. See
for more information.