GS12281 datasheet(54/97 Pages) SEMTECH

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GS12281

Final Data Sheet

Rev.9

PDS-061385

February 2019

54 of 97

Semtech

Proprietary & Confidential

www.semtech.com

3. Write the Data Word to be written to the next register in Auto Increment mode, etc.

Read access is the same as the above with the exception of step 1, where the Command

Word 1 is set for read access (R/W = 1).

Note: The UNIT ADDRESS field of Command Word 1 must always match

DEV_UNIT_ADDRESS for an access to be accepted by the device. Changing

DEV_UNIT_ADDRESS to a value other than 0 is only required if multiple devices are

connected to a single chip select (in Loop-Through or Bus-Through configuration).

4.9.11 Clear Sticky Counts Through Four Way Handshake

There are three sticky counters that keep count of changes in status of primary carrier

detect, rate changes, and lock changes. The counters can be read from the following

three parameters in register 0x84 and 0x85: STAT_CNT_PRI_CD_CHANGES,

STAT_CNT_RATE_CHANGES, and STAT_CNT_PLL_LOCK_CHANGES. The counters

saturate at 255 (0xFF) and must be cleared before additional status changes can be

counted. The following four way handshake procedures clears the counters.

1. Poll STAT_CLEAR_COUNTS_STATUS parameter until equal to 0 (idle), then set

CTRL_CLEAR_COUNTS = 1 (clear sticky counts).

2. Poll STAT_CLEAR_COUNTS_STATUS parameter until equal to 2 (cleared), then

reset CTRL_CLEAR_COUNTS to 0.

The device will now reset STAT_CLEAR_COUNTS_STATUS to 0 (idle) and the clearing

process can be repeated at any time.

4.9.12 Device Power Up Sequence

If all power supplies cannot be guaranteed to power up simultaneously, ensure that

VCC_DDI powers up first. Please note that there is no minimum time requirement

between power supply initializations after VCC_DDI is energized.

Note: Please check with your local FAE (field applications engineer), as some devices

may need updated configuration settings. If a configuration file has been provided by

the FAE, see the timing information in the Serial Routing and Distribution Product

Configuration Loading Procedure Application Note (PDS-061176).

4.9.12.1 Power-Up Timing Sequence

The following timing sequence must be observed after power-up when no external

configuration loading is required. See Figure 4-27 for the timing requirements of Steps

1 and 2 below.

Step 1 – No GSPI Access Allowed

a) Device supply reaches 90% of target. POR (Power On Reset) is activated.

b) Internal blocks reset, default device configuration boot-up begins.

c) Default device configuration boot-up process.

Step 2 – GSPI Access Allowed

a) Host sets EYE_MON_INT_CFG_3 (register address 0x57) to 0x8006.

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