xr16l2750im Exar Corporation, xr16l2750im Datasheet - Page 13

• Manufacturer Part Number: xr16l2750im
• Description: High-performance 2.25v - 5.5v Duart
• Manufacturer: Exar Corporation

xr
REV. 1.2.1
The Receive Holding Register is an 8-bit register that holds a receive data byte from the Receive Shift
Register. It provides the receive data interface to the host processor. The RHR register is part of the receive
FIFO of 64 bytes by 11-bits wide, the 3 extra bits are for the 3 error tags to be reported in LSR register. When
the FIFO is enabled by FCR bit-0, the RHR contains the first data character received by the FIFO. After the
RHR is read, the next character byte is loaded into the RHR and the errors associated with the current data
byte are immediately updated in the LSR bits 2-4.
N
F
F
2.12.1
OTE
IGURE
IGURE
: Table-B selected as Trigger Table for
Receive Data
Byte and Errors
9. R
10. R
16X or 8X Clock
64 bytes by 11-bit
1 6 X o r 8 X C lo ck
(EMSR bit-7)
(E M S R b it-7 )
Receive Holding Register (RHR) - Read-Only
a n d E rro rs
D a ta B yte
R ece ive
ECEIVER
wide
FIFO
ECEIVER
O
O
PERATION IN NON
PERATION IN
Receive Data Shift
Register (RSR)
LS R b its
T a g s in
E rro r
4 :2
Data FIFO
Receive
Receive
FIFO
Data
R e ce ive D a ta S hift
-FIFO M
Figure 10
R e giste r (R S R )
AND
H o ldin g R e g ister
R e ce ive D a ta
A
ODE
Validation
Data falls to
(R H R )
UTO
Data Bit
Data fills to
Trigger=16
(
Example
Table 10
FIFO
24
8
RTS F
: - RX FIFO trigger level selected at 16
13
LOW
).
RTS# re-asserts when data falls below the flow
control trigger level to restart remote transmitter.
Enable by EFR bit-6=1, MCR bit-1.
RTS# de-asserts when data fills above the flow
control trigger level to suspend remote transmitter.
Enable by EFR bit-6=1, MCR bit-1.
(See Note Below)
RHR Interrupt (ISR bit-2) programmed for
desired FIFO trigger level.
FIFO is Enabled by FCR bit-0=1
V alid a tio n
D ata B it
2.25V TO 5.5V DUART WITH 64-BYTE FIFO
C
bytes
ONTROL
R H R Inte rru pt (IS R b it-2 )
M
ODE
Receive Data Characters
R e ce ive D a ta C h a ra cte rs
R X F IF O 1
XR16L2750
RXFIFO1