SCI Control Registers
1735
SPNU563A – March 2018
Copyright © 2018, Texas Instruments Incorporated
Serial Communication Interface (SCI) Module
30.7.2 SCI Global Control Register 1 (SCIGCR1)
The SCIGCR1 register defines the frame format, protocol, and communication mode used by the SCI.
and
illustrate this register.
Figure 30-9. SCI Global Control Register 1 (SCIGCR1) [offset = 04h]
31
26
25
24
Reserved
TXENA
RXENA
R-0
R/W-0
R/W-0
23
18
17
16
Reserved
CONT
LOOP BACK
R-0
R/W-0
R/W-0
15
10
9
8
Reserved
POWERDOWN
SLEEP
R-0
R/WP-0
R/W-0
7
6
5
4
3
2
1
0
SWnRST
Reserved
CLOCK
STOP
PARITY
PARITY ENA
TIMING MODE
COMM MODE
R/W-0
R-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
LEGEND: R/W = Read/Write; R = Read only; WP = Write in privileged mode only; -
n
= value after reset
NOTE:
The SCIGCR1 Control Register Bits should not be changed during Frame Transmission or
Reception.
Table 30-5. SCI Global Control Register 1 (SCIGCR1) Field Descriptions
Bit
Field
Value
Description
31-26
Reserved
0
Reads return 0. Writes have no effect.
25
TXENA
Transmit enable. Data is transferred from SCITD to the SCITXSHF shift out register only when the
TXENA bit is set.
0
Disable transfers from SCITD to SCITXSHF.
1
Enable SCI to transfer data from SCITD to SCITXSHF.
Note: Data written to SCITD or the transmit multi-buffer before TXENA is set is not
transmitted. If TXENA is cleared while transmission is ongoing, the data previously written
to SCITD is sent.
24
RXENA
Receive enable. RXENA allows or prevents the transfer of data from SCIRXSHF to SCIRD.
0
The receiver will not transfer data from the shift buffer to the receive buffer.
1
The receiver will transfer data from the shift buffer to the receive buffer.
Note: Clearing RXENA stops received characters from being transferred into the receive
buffer or multi-buffers, prevents the RX status flags from being updated by receive data, and
inhibits both receive and error interrupts. However, the shift register continues to assemble
data regardless of the state of RXENA.
Note: If RXENA is cleared before a frame is completely received, the data from the frame is
not transferred into the receive buffer.
Note: If RXENA is set before a frame is completely received, the data from the frame is
transferred into the receive buffer. If RXENA is set while SCIRXSHF is in the process of
assembling a frame, the status flags are not assured to be accurate for that frame. To ensure
that the status flags correctly reflect what was detected on the bus during a particular frame,
RXENA should be set before the detection of that frame.
23-18
Reserved
0
Reads return 0. Writes have no effect.
17
CONT
Continue on suspend. This bit has an effect only when a program is being debugged with an
emulator, and it determines how the SCI operates when the program is suspended. The
0
When debug mode is entered, the SCI state machine is frozen. Transmissions are halted and
resume when debug mode is exited.
1
When debug mode is entered, the SCI continues to operate until the current transmit and receive
functions are complete.