XR16C850 Ver la hoja de datos (PDF) - Exar Corporation
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XR16C850 Datasheet PDF : 55 Pages
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XR16C850
SYMBOL DESCRIPTION
Symbol
Pin
Signal
40 44 48 52 type
Pin Description
mode is selected, this pin functions as the LPT-2
printer port decode logic output, see table 2. During
the STD mode this pin goes to a logic 0 when the
external CPU is reading data from the 850. This
signal can be used to disable external transceivers
or other logic functions. Also, this pin may be D12
signal when BUS16 is selected in 48 and 52 pin
packages.
-OP1/RS485
34
38
34
37
O Output-1(User Defined) or RS-485 direction control
signal. General purpose output during normal opera-
tion - See bit-2 of modem control register (MCR bit-
2). RS-485 direction control can be selected when
FCTR Bit-3 is set to “1”. During data transmit cycle,
-OP1/RS485 pin is low.
-OP2
(See S3)
RCLK
(See S2)
RESET
35 39 35 38
I
Reset. (active high) - A logic 1 on this pin will reset
the internal registers and all the outputs. During
reset, the UART transmitter output and the receiver
input are disabled, the data bus is still controlled by
CS0, CS1, -CS2 and -IOR. (See XR16C850 External
Reset Conditions for initialization details.)
-RXRDY
(See IRQB)
S1
-
23 21 23
I
Port Select-1 (internal pull-up) - When PC mode is
selected, S1 is used in conjunction with S2, S3 and
A3-A9 to select one of the PC COM port addresses
(see Table 2 Internal Address Decode Function)
This pin has no function in the STD mode.
S2 / RCLK
9
10
5
5
I
Port Select-2 or Receive Clock Input (dual function
input with internal pull-up) - When PC mode is
selected, the RCLK input is connected internally to
-BAUDOUT and S2 is used in conjunction with S1,
S3 and A3-A9 to select one of the PC COM port
addresses. During STD mode operation, this pin is
used as external 16X clock input to the receiver
section, normally it’s connected to -BAUDOUT.
Rev. 1.20
9
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