eUSCI_B I2C Registers
980
SLAU356I – March 2015 – Revised June 2019
Copyright © 2015–2019, Texas Instruments Incorporated
Enhanced Universal Serial Communication Interface (eUSCI) – I
2
C Mode
26.4.2 UCBxCTLW1 Register
eUSCI_Bx Control Word Register 1
Figure 26-18. UCBxCTLW1 Register
15
14
13
12
11
10
9
8
Reserved
UCETXINT
r0
r0
r0
r0
r0
r0
r0
rw-0
7
6
5
4
3
2
1
0
UCCLTO
UCSTPNACK
UCSWACK
UCASTPx
UCGLITx
rw-0
rw-0
rw-0
rw-0
rw-0
rw-0
rw-0
rw-0
Modify only when UCSWRST = 1.
Table 26-5. UCBxCTLW1 Register Description
Bit
Field
Type
Reset
Description
15-9
Reserved
R
0h
Reserved
8
UCETXINT
RW
0h
Early UCTXIFG0. Only in slave mode. When this bit is set, the slave addresses
defined in UCxI2COA1 to UCxI2COA3 must be disabled.
Modify only when UCSWRST = 1.
0b = UCTXIFGx is set after an address match with UCxI2COAx and the direction
bit indicating slave transmit
1b = UCTXIFG0 is set for each START condition
7-6
UCCLTO
RW
0h
Clock low timeout select.
Modify only when UCSWRST = 1.
00b = Disable clock low timeout counter
01b = 135 000 SYSCLK cycles (approximately 28 ms)
10b = 150 000 SYSCLK cycles (approximately 31 ms)
11b = 165 000 SYSCLK cycles (approximately 34 ms)
5
UCSTPNACK
RW
0h
The UCSTPNACK bit allows to make the eUSCI_B master acknowledge the last
byte in master receiver mode as well. This is not conform to the I2C specification
and should only be used for slaves, which automatically release the SDA after a
fixed packet length.
Modify only when UCSWRST = 1.
0b = Send a not acknowledge before the STOP condition as a master receiver
(conform to I2C standard)
1b = All bytes are acknowledged by the eUSCI_B when configured as master
receiver
4
UCSWACK
RW
0h
Using this bit it is possible to select, whether the eUSCI_B module triggers the
sending of the ACK of the address or if it is controlled by software.
0b = The address acknowledge of the slave is controlled by the eUSCI_B
module
1b = The user needs to trigger the sending of the address ACK by issuing
UCTXACK
3-2
UCASTPx
RW
0h
Automatic STOP condition generation. In slave mode only UCBCNTIFG is
available.
Modify only when UCSWRST = 1.
00b = No automatic STOP generation. The STOP condition is generated after
the user sets the UCTXSTP bit. The value in UCBxTBCNT is a don't care.
01b = UCBCNTIFG is set with the byte counter reaches the threshold defined in
UCBxTBCNT
10b = A STOP condition is generated automatically after the byte counter value
reached UCBxTBCNT. UCBCNTIFG is set with the byte counter reaching the
threshold.
11b = Reserved