DS21352L datasheet(21/137 Pages) DALLAS

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DS21352/DS21552

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4.1.3 PARALLEL CONTROL PORT PINS

Signal Name:

INT*

Signal Description:

Interrupt

Signal Type:

Output

Flags host controller during conditions and change of conditions defined in the Status Registers 1 and 2 and the HDLC Status

Signal Name:

FMS

Signal Description:

Framer Mode Select

Signal Type:

Input

Selects the DS2152 mode when high or the DS21352/552 mode when low. If high, the JTRST is internally pulled low. If low,

JTRST has normal JTAG functionality. This pin has a 10k pull up resistor.

Signal Name:

TEST

Signal Description:

3–State Control

Signal Type:

Input

Set high to 3–state all output and I/O pins (including the parallel control port) when FMS = 1 or when FMS = 0 and JTRST* is

tied low. Set low for normal operation. Ignored when FMS = 0 and JTRST* = 1. Useful for board level testing.

Signal Name:

MUX

Signal Description:

Bus Operation

Signal Type:

Input

Set low to select non–multiplexed bus operation. Set high to select multiplexed bus operation.

Signal Name:

AD0 TO AD7

Signal Description:

Data Bus [D0 to D7] or Address/Data Bus

Signal Type:

Input

In non–multiplexed bus operation (MUX = 0), serves as the data bus. In multiplexed bus operation (MUX = 1), serves as a 8–

bit multiplexed address / data bus.

Signal Name:

A0 TO A6

Signal Description:

Address Bus

Signal Type:

Input

In non–multiplexed bus operation (MUX = 0), serves as the address bus. In multiplexed bus operation (MUX = 1), these pins

are not used and should be tied low.

Signal Name:

BTS

Signal Description:

Bus Type Select

Signal Type:

Input

Strap high to select Motorola bus timing; strap low to select Intel bus timing. This pin controls the function of the RD*(DS*),

ALE(AS), and WR*(R/W*) pins. If BTS = 1, then these pins assume the function listed in parenthesis ().

Signal Name:

RD*(DS*)

Signal Description:

Read Input - Data Strobe

Signal Type:

Input

RD* and DS* are active low signals. DS active HIGH when MUX = 0. See bus timing diagrams.

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