xr16c2852ij Exar Corporation, xr16c2852ij Datasheet - Page 9

• Manufacturer Part Number: xr16c2852ij
• Description: 2.97v To 5.5v Dual Uart With 128-byte Fifos
• Manufacturer: Exar Corporation

xr
REV. 2.1.1
The INTA and INTB interrupt output changes according to the operating mode and enahnced features setup.
Table 3 and 4
through 25.
The 2852 includes an on-chip oscillator (XTAL1 and XTAL2) to produce a clock for both UART sections in the
device. The CPU data bus does not require this clock for bus operation. The crystal oscillator provides a
system clock to the Baud Rate Generators (BRG) section found in each of the UART. XTAL1 is the input to the
oscillator or external clock buffer input with XTAL2 pin being the output. For programming details, see
“Programmable Baud Rate Generator.”
2.8
2.9
RXRDY# A/B
TXRDY# A/B
INTA/B Pin
INTA/B Pin
INTA/B Pin
P
INS
INTA and INTB Ouputs
Crystal Oscillator or External Clock Input
LOW = no data
HIGH = 1 byte
HIGH = byte in THR
summarize the operating behavior for the transmitter and receiver. Also see Figures
LOW = THR empty
Auto RS485
(FIFO D
HIGH = no data
LOW = 1 byte
FCR
Mode
YES
NO
(FIFO D
T
FCR B
ABLE
BIT
ISABLED
T
-0=0
ABLE
T
2: TXRDY#
IT
ISABLED
ABLE
-0 = 0
LOW = a byte in THR
HIGH = THR empty
LOW = a byte in THR
HIGH = transmitter empty
)
3: INTA
4: INTA
LOW = at least 1 byte in FIFO
HIGH = FIFO empty
LOW = FIFO empty
HIGH = at least 1 byte in FIFO
)
(FIFO D
FCR B
(DMA M
AND
AND
AND
IT
ISABLED
LOW = FIFO below trigger level
HIGH = FIFO above trigger level
FCR B
INTB P
-0 = 0
RXRDY# O
ODE
INTB P
IT
)
-3 = 0
D
INS
ISABLED
IN
9
2.97V TO 5.5V DUAL UART WITH 128-BYTE FIFOS
O
UTPUTS IN
O
LOW = FIFO above trigger level
HIGH = FIFO below trigger level or FIFO empty
LOW = FIFO above trigger level
HIGH = FIFO below trigger level or transmitter empty
PERATION FOR
PERATION
FCR B
)
IT
HIGH to LOW transition when FIFO reaches the
trigger level, or timeout occurs.
LOW to HIGH transition when FIFO empties.
LOW = FIFO has at least 1 empty location
HIGH = FIFO is full
-0=1 (FIFO E
FIFO
F
(FIFO E
OR
FCR B
T
AND
RANSMITTER
R
ECEIVER
(FIFO E
IT
NABLED
DMA M
FCR B
(DMA M
-0 = 1
NABLED
FCR B
)
IT
NABLED
ODE
-0 = 1
ODE
)
IT
-3 = 1
E
)
NABLED
XR16C2852
)
20