GS12281 datasheet(47/97 Pages) SEMTECH

47 / 97 page

GS12281

Final Data Sheet

Rev.9

PDS-061385

February 2019

47 of 97

Semtech

Proprietary & Confidential

www.semtech.com

4.9.5.2 B'CAST ALL—B14 Command Word 1

This bit is used in write operations to configure all devices connected in Loop-Through

and Bus-Through configuration with a single command.

When B’CAST ALL is set to 1, the following Data Word (AUTOINC = 0) or Data Words

(AUTOINC = 1) are written to the register specified by the ADDRESS field of the

Command Words (and subsequent addresses when AUTOINC = 1), regardless of the

setting of the UNIT ADDRESS(es).

When B’CAST ALL is set to 0, a normal write operation is indicated. Only those devices

that have a Unit Address matching the UNIT ADDRESS field of Command Word 1 write

the Data Word to the register specified by the ADDRESS field of the Command Words.

4.9.5.3 EMEM—B13 Command Word 1

The EMEM bit must be set to 1 in Command Word 1. When EMEM is set to 1, a 23-bit

address split between Command Word 1 and Command Word 2 is used to access the

registers in this device.

4.9.5.4 AUTOINC—B12 Command Word 1

When AUTOINC is set to 1, Auto-Increment read or write access is enabled.

In Auto-Increment Mode, the device automatically increments the register address for

each contiguous read or write access, starting from the address defined in the ADDRESS

field of the Command Word.

The internal address is incremented for each 16-bit read or write access until a

LOW-to-HIGH transition on the CS pin is detected.

When AUTOINC is set to 0, single read or write access is required.

Auto-Increment write must not be used to update values in CONTROL_REG.

4.9.5.5 UNIT ADDRESS—B11:B7 Command Word 1

The 5 bits of the UNIT ADDRESS field of the Command Word are used to select one of 32

devices connected on a single chip select in Loop-Through or Bus-Through

configurations.

Read and write accesses are only accepted if the UNIT ADDRESS field matches the

programmed DEV_UNIT_ADDRESS in CONTROL_REG.

By default at power-up or after a device reset, the DEV_UNIT_ADDRESS is set to 00h.

4.9.5.6 ADDRESS—B6:B0 Command Word 1 and B15:B0 Command Word 2

The Command and Data Word formats are shown in Figure 4-13 and Figure 4-14. As an

example of the command word structure, reading register 0x90 from a device with unit

address 3, that has AUTOINC = 0, and B’CAST ALL = 0 would be structured as follows:

•

Command word 1: 1010 0001 1000 0000 (0xA180)

•

Command word 2: 0000 0000 1001 0000 (0x90)

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