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IDT82P2521
21(+1) CHANNEL HIGH-DENSITY E1 LINE INTERFACE UNIT
Pin Description
24
December 7, 2005
GPIO[0]
GPIO[1]
Output / Input
AF9
AF10
GPIO: General Purpose I/O [1:0]
These two pins can be defined as input pins or output pins by the DIR[1:0] bits (b1~0,
GPIO)respectively.
When the pins are input, their polarities are indicated by the LEVEL[1:0] bits (b3~2,
GPIO)respectively.
When the pins are output, their polarities are controlled by the LEVEL[1:0] bits (b3~2,
GPIO)respectively.
RST
Input
AG10
RST: Reset (Active Low)
A low pulse on this pin resets the device. This hardware reset process completes in 2 s max-
INT
Output
AK16
INT: Interrupt Request
This pin indicates interrupt requests for all unmasked interrupt sources.
The output characteristics (open drain or push-pull internally) and the active level are deter-
mined by the INT_PIN[1:0] bits (b3~2,
GCF).CS
Input
AJ17
CS: Chip Select (Active Low)
This pin must be asserted low to enable the microprocessor interface.
A transition from high to low must occur on this pin for each Read/Write operation and CS
should remain low until the operation is over.
P/S
Input
AG16
P/S: Parallel or Serial Microprocessor Interface Select
P/S selects Serial or Parallel microprocessor interface for the device:
GNDD - Serial microprocessor interface.
VDDIO - Parallel microprocessor interface.
Serial microprocessor interface consists of the CS, SCLK, SDI, SDO pins.
Parallel microprocessor interface consists of the CS, INT/MOT, IM, DS/RD, ALE/AS, R/W/WR,
ACK/RDY, D[7:0], A[10:0] pins.
INT/MOT
Input
(Pull-Up)
AF14
INT/MOT: Intel or Motorola Microprocessor Interface Select
In Parallel microprocessor interface, INT/MOT selects Intel or Motorola microprocessor inter-
face for the device:
GNDD - Parallel Motorola microprocessor interface.
Open - Parallel Intel microprocessor interface.
In Serial microprocessor interface, this pin should be left open.
IM
Input
(Pull-Up)
AF15
IM: Interface Mode Selection
In Parallel Motorola or Intel microprocessor interface, IM selects multiplexed bus or non-multi-
plexed bus for the device:
GNDD - Parallel Motorola /Intel Non-Multiplexed microprocessor interface.
Open - Parallel Motorola /Intel Multiplexed microprocessor interface.
In Serial microprocessor interface, this pin should be connected to GNDD.
ALE / AS
Input
AG15
ALE: Address Latch Enable
In Parallel Intel Multiplexed microprocessor interface, this multiplex pin is used as ALE.
The address on A[10:8] and D[7:0] (A[7:0] are ignored) is sampled into the device on the fall-
ing edges of ALE.
AS: Address Strobe
In Parallel Motorola Multiplexed microprocessor interface, this multiplex pin is used as AS.
The address on A[10:8] and D[7:0] (A[7:0] are ignored) is latched into the device on the falling
edges of AS.
In Parallel Motorola /Intel Non-Multiplexed microprocessor interface, this pin should be pulled
high.
In Serial microprocessor interface, this pin should be connected to GNDD.
Name
I / O
Pin No.
Description