TP3410 datasheet(13/32 Pages) NSC

13 / 32 page

Functional Description (Continued)

The TP3410 has an enhanced MICROWIRE port such that it

can connect to standard MICROWIRE master devices (such

an NSC’s HPC and COP families) as well as the SCP (serial

control port) interface master from the Motorola micro-con-

troller family

SCP is supported on devices such as

MC68302 or the MC145488 HDLC

TP3410 supports two popular formats used in typical termi-

nal equipment applications

1 CCLK idling LOW when CS pin is inactive HIGH pulsing

LOWHIGHLOW for 16 clocks then returning back to

LOW for idle condition Data is output on CO pin on the

negative edge and data sampled in on the positive edge

of CCLK This format (shown in

Figure 14b ) is normally

used with NSC’s microcontrollers from the HPC or the

COP8 family

2 CCLK idling HIGH when CS pin inactive HIGH pulsing

HIGHLOWHIGH for 17 clocks then returning back to

HIGH for idle condition Data is output on CO pin on the

negative edge and data sampled in on the positive edge

of CCLK This format (shown in

Figure 14c ) is normally

used with other alternate microcontrollers in the industry

The first 16 clock pulses are the normal low-going pulses

to shift and sample the microwire data The 17th pulse is

generated with software

by toggling the CCLK clock

polarity bit on the SCP port of MC6302 or MC145488 It

is necessary to deactivate the CS pin (bring it high) while

the CCLK is low as shown in

Figure 14c

80 GCI MODE (MWe0)

Selected by tying the MW pin low the GCI interface is de-

signed for systems in which PCM and control data are multi-

plexed together into 4 contiguous bytes per 8 kHz frame

Furthermore in Subscriber Line Cards and NT1 – 2’s (where

the Digital Interface is slaved to external timing) up to 8 GCI

channels may be carried in 1 frame of a GCI multiplex with

a combined bit rate from 256 kbs up to 3088 kbs Pin-pro-

grammable GCI-channel assignment for 8 GCI channels is

provided

Note that GCI mode on the TP3410 requires messages in

the Embedded Operations Channel to be processed by a

local microcontroller In Line card and TE applications GCI

mode can be used with a device such as the TP3451 HDLC

controller to provide the interface for the microcontroller to

access the EOC Registers To use the device in an NT-1 or

Regenerator a microcontroller is required and Microwire

mode should be used on the TP3410

81 GCI Physical Interface

The interface physically consists of four wires

Transmit data to line

Receive data from line

Bit clock at 2 cyclesbit

BCLK

8 kHz frame sync

FSa

Data is synchronized by the BCLK and FSa clock inputs

FSa insures re-initialization of the time-slot counter at the

beginning of each 8 kHz frame with the rising edge of FSa

being the reference time for the first GCI channel bit Data is

clocked in both directions at half the BCLK input frequency

Data bits are output from the device on a rising edge of

BCLK and sampled on the second falling edge of BCLK

unused slots are high impedance Br is an open-drain n-

channel output with internal detection for contention resolu-

tion on the Monitor and CI channels between devices at-

tempting to use the same GCI channel (typically in a TE

application)

A device may be either the Master or Slave of the GCI tim-

ing As a Master it is the source of BCLK FSa and FSb

which are synchronized to the data received from the line

and GCI channel 0 is always used As a GCI Slave BCLK

and FSa must be sourced externally typically from a system

backplane and pins S0 – S2 must be connected high or low

to select the required GCI channel To use the single chan-

nel mode a 512 kHz BCLK is required and S2 S1 and S0

must be connected to GND (GCI Channel 0) To use the

multiplex mode with a GCI Slave device the 4 pins are com-

moned between up to 8 devices forming a ‘‘wire-AND’’ con-

nection with the Br pins The BCLK frequency must be at

least n c 512 kHz where n is the number of devices In fact

BCLK may be operated up to 6144 kHz if required to leave

up to 4 additional GCI channels unoccupied by TP3410’s

(and available for other uses) Clock and channel selection

are shown in the following table

Pin Name

LT and NT1 – 2

NT1 and TE

0 (GCI Slave)

1 (GCI Master)

S2CLS

S2 (msb)

CLSe0

512 kHz

CLSe1 1536 kHz

S0FSb

S0 (lsb)

FSb

TLH9151 – 15

FIGURE 6 Microwire Control Port Timing MW e 1

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