DS26521 datasheet(29/258 Pages) MAXIM

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DS26521 Single T1/E1/J1 Transceiver

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8.3

Resets and Power-Down Modes

A hardware reset is issued by forcing the

RESETB pin to logic-low. The RESETB input pin resets all framers, LIUs,

and BERTs. Note that not all registers are cleared to 00h on a reset condition. The register space must be

reinitialized to appropriate values after a hardware or software reset has occurred. This includes writing

reserved locations to 00h.

The DS26521 has several features included to reduce power consumption. The LIU transmitter can be powered

down by setting the TPDE bit in the LIU Maintenance Control register (LMCR). Note that powering down the

transmit LIU results in a high-impedance state for the corresponding TTIP and TRING pins and reduced operating

current. The RPDE bit in the LMCR register can be used to power down the LIU receiver.

The TE (transmit enable) bit in the LMCR register can be used to disable the TTIP and TRING outputs and place

them in a high-impedance mode, while keeping the LIU in an active state (powered up). This is useful for

equipment protection-switching applications.

Table 8-1. Reset Functions

RESET FUNCTION

LOCATION

COMMENTS

Hardware Device Reset

RESETB

Transition to a logic 0 level resets the DS26521.

Hardware JTAG Reset

JTRST

Resets the JTAG test port.

Global Framer and BERT Reset

GFSRR.0

Writing to this bit resets the framer and BERT (transmit and

receive).

Global LIU Reset

GLSRR.0

Writing to this bit resets the associated LIU.

Framer Receive Reset

RMMR.1

Writing to this bit resets the receive framer.

Framer Transmit Reset

TMMR.1

Writing to this bit resets the transmit framer.

HDLC Receive Reset

RHC.6

Writing to this bit resets the receive HDLC controller.

HDLC Transmit Reset

THC1.5

Writing to this bit resets the transmit HDLC controller.

Elastic Store Receive Reset

RESCR.2

Writing to this bit resets the receive elastic store.

Elastic Store Transmit Reset

TESCR.2

Writing to this bit resets the transmit elastic store.

Bit Oriented Code Receive Reset

T1RBOCC.7

Writing to this bit resets the receive BOC controller.

Loop Code Integration Reset

T1RDNCD1,

T1RUPCD1

Writing to these registers resets the programmable in-band

code integration period.

Spare Code Integration Reset

T1RSCD1

Writing to this register resets the programmable in-band

code integration period.

DS26521 Datasheet(PDF) 29 Page - Maxim Integrated Products

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