SB16C1054PCI_Data Sheet_EN

SB16C1054PCI
PCI Target Interface Controller
with Quad-UART
JULY 2013 REV 1.04
42
Xoff Re-transmit function transmits Xoff character again when more data arrives from
external UART though it transmitted Xoff character before. By this function the external
UART can recognize Xoff character and stop transmitting data though it didn’t recognize
the Xoff character before.
There are four Xoff Re-transmitting settings by XRCR[1:0]. Xoff character can be re-
transmitted when every 1, 4, 8 or 16 data arrives in XOFF status.
If XRCR[1:0] is 00b, Xoff character is re-transmitted whenever 1 more data arrives in
XOFF status. If XRCR[1:0] is ‘01’, Xoff character is re-transmitted whenever 4 more data
arrives in XOFF status.
If ‘10’, 8 more data and if 11b, 16 more data. If the value of FUR is approaching the FIFO
size, 256-byte, it is good to write XRCR[1:0] 00b. If the 256-FUR value is small, it is good
to select 00b of XRCR and if large, it is good to select 11b.
Xoff Re-transmit function is enabled by MCR[6] and MCR[2]. Change MCR[2] from
OP1# function to Xoff Re-transmit function by setting MCR[6] to 1b and set MCR[2] to 1b
again. Then Xoff Re-transmit function is enabled. When disabling it, first set MCR[6] to 1b
and then clear MCR[2] to 0b.
12.4 Sleep Mode with Auto Wake-Up
The SB16C1050 provides sleep mode operation to reduce its power consumption when
sleep mode is activated. Sleep mode is enabled when EFR[4] and IER[4] are set to 1b.
Sleep mode is activated when:
■
■
■
■
RXD input is in idle state.
CTS#, DSR#, DCD#, and RI# are not toggling.
The TX FIFO and TSR are in empty state.
No interrupt is pending except THR and time-out interrupts.
In sleep mode, the SB16C1050 clock and baud rate clock are stopped. Since most
registers are clocked using these clocks, the power consumption is greatly reduced.
Normal operation is resumed when:
■
■
■
RXD input receives the data start bit transition.
Data byte is loaded to the TX FIFO or THR.
CTS#, DSR#, DCD#, and RI# inputs are changed.