
xr
ST16C654/654D
REV. 5.0.2
2.97V TO 5.5V QUAD UART WITH 64-BYTE FIFO
45
FIGURE 25. TRANSMIT READY & INTERRUPT TIMING [FIFO MODE, DMA MODE ENABLED] FOR CHANNELS A-D
TX
TXRDY#
IOW#
INT*
D0:D7
S
TXDMA
D0:D7
S
D0:D7
T
D0:D7
S
D0:D7
S
T
D0:D7
S
T
D0:D7
S
T
Start
Bit
Stop
Bit
T
WRI
T
(Unloading)
(Loading data
into FIFO)
Last Data Byte
Transmitted
TX FIFO fills up
to trigger level
TX FIFO drops
below trigger level
At least 1
empty location
in FIFO
T
SRT
TX FIFO
Full
T
WT
T
SI
ISR Read
*INT cleared when the ISR is read or when TX FIFO fills up to trigger level.
IER[1]
enabled