RX FIFO 15
RX FIFO 0
RX BUF
RXSHF
TX FIFO 15
TX FIFO 0
TX
RX
16x8 bit FIFO
RXFFOVF flag
RXFFIL
RXERR flag
RXRDY/BRKDT
TXFFIL
1
0
RXINT
RXFFIENA
RXERRINTENA
RX/BKINTENA
TXFFIENA
TX BUF
TXSHF
SCIFFENA
TXRDY flag
TXINTENA
SCIFFENA
0
1
TXINT
Auto-baud
detect logic
ABD bit
CDC bit
Enhanced SCI Module Overview
1028
SPRUHE8E – October 2012 – Revised November 2019
Copyright © 2012–2019, Texas Instruments Incorporated
C28 Serial Communications Interface (SCI)
With the 256 clock delay the SCI module can transmit data in a maximum delayed mode with the FIFO
words shifting out with a delay of 256 baud clocks between each words. The programmable delay
facilitates communication with slow SCI/UARTs with little CPU intervention.
8.
FIFO status bits.
Both the transmit and receive FIFOs have status bits TXFFST or RXFFST (bits 12
−
0)
that define the number of words available in the FIFOs at any time. The transmit FIFO reset bit
TXFIFO and receive reset bit RXFIFO reset the FIFO pointers to zero when these bits are cleared to 0.
The FIFOs resumes operation from start once these bits are set to one.
9.
Programmable interrupt levels.
Both transmit and receive FIFO can generate CPU interrupts. The
interrupt trigger is generated whenever the transmit FIFO status bits TXFFST (bits 12
−
8) match (less
than or equal to) the interrupt trigger level bits TXFFIL (bits 4
−
0 ). This provides a programmable
interrupt trigger for transmit and receive sections of the SCI. Default value for these trigger level bits
will be 0x11111 for receive FIFO and 0x00000 for transmit FIFO, respectively.
and
explain the operation/configuration of SCI interrupts in nonFIFO/FFO mode.
Figure 13-10. SCI FIFO Interrupt Flags and Enable Logic
(1)
FIFO mode TXSHF is directly loaded after delay value, TXBUF is not used.
(2)
RXERR can be set by BRKDT, FE, OE, PE flags. In FIFO mode, BRKDT interrupt is only through RXERR flag
Table 13-6. SCI Interrupt Flags
FIFO Options
(1)
SCI Interrupt Source
Interrupt Flags
Interrupt Enables
FIFO Enable
SCIFFENA
Interrupt Line
SCI without FIFO
Receive error
RXERR
(2)
RXERRINTENA
0
RXINT
Receive break
BRKDT
RX/BKINTENA
0
RXINT
Data receive
RXRDY
RX/BKINTENA
0
RXINT
Transmit empty
TXRDY
TXINTENA
0
TXINT
SCI with FIFO
Receive error and
receive break
RXERR
RXERRINTENA
1
RXINT