XRT8001IP datasheet(22/48 Pages) EXAR

22 / 48 page

XRT8001

Rev. 1.01

Step 3 – Upon reviewing Table 4, write the listed value

(under the “Value to Write to D4 – D1 in CR0” Register

Column) into the D4 through D1 bit-fields within Com-

mand Register CR0, as illustrated below.

Note: If the user wishes to output a clock signal via the

CLK1 output signal, then he/she should also write a “1” into

the “PL1EN” bit-field within Command Register CR0.

This step configures the XRT8001 to operate in the

“Forward/Master” Mode.

Step 4 – Next, you need to specify the value for “N”

(e.g., as in the “N x 1.544MHz” or “N x 2.048MHz” clock

signal which is to be applied to the “FIN” input pin.)

In order to specify the value for “N”, one needs to write

the value of “N - 1” (in binary format) into the “D4 through

D1” bits within Command Register CR1, as illustrated

below.

Command Register CR0 (Address = 0x00)

IOC4

IOC3

IOC2

IOC1

PL1EN

Value to Write to D4 – D1 in CR0

Command Register, CR1 (Address = 0x01)

PL2EN

Value of “N - 1” (in Binary Format)

For example, if the user wishes to configure the

XRT8001 to accept a 1.544MHz clock signal, via the

“FIN” input pin (e.g., N = 1), then the user should write

in the value “0”, into Command Register CR1.

Note: If the user wishes to output a clock signal via the

CLK2 output signal, then he/she should also write a “1” into

the “PL2EN” bit-field within Command Register CR1.

Step 5 – Specify the value of “K” (e.g., as in the “K x

56kHz” or “K x 64kHz” clock signal which is to be output

via the CLK1 output signal).

Command Register, CR2 (Address = 0x02)

SEL14

SEL13

SEL12

SEL11

SEL10

Value of “K - 1” (in Binary Format).

For example, if one wishes to configure the XRT8001

to output a clock signal of either “56kHz” or “64kHz”

(e.g., where “K” = 1) via the CLK1 output pin, then he/

she should write the value “0”, into Command Register

CR2.

Step 6 – Specify the value of “K” (e.g., as in the “K x

56kHz” or “K x 64kHz” clock signal which is to be output

via the CLK2 output signal).

In order to specify the value for “K”, one needs to write

the value of “K - 1” (binary format) into Command

Command Register, CR3 (Address = 0x03)

SEL24

SEL23

SEL22

SEL21

SEL20

Value of “K - 1” (in Binary Format).

For example, if one wishes to configure the XRT8001

to output a clock signal of either “1.792MHz” or

“2.048MHz” (e.g., where “K” = 32) via the CLK2 output

pin, then he/she should write the value “31” (or “1 1 1

1 1” in binary format) into Command Register CR3.

Step 7 – Enable any of the following output signals as

appropriate:

“SYNC”, “CLK1”, “CLK2” and

“LOCKDET”.

This is accomplished by writing a “1” into the corre-

sponding bit-fields, within Command Register CR4, as

illustrated below.

Command Register CR4, (Address = 0x04)

SYNCEN

CLK1EN

CLK2EN

LDETDIS2

LDETDIS1

Note: For information on the “LDETDIS1” and “LDETDIS2”

bit-fields, please see Table 3.

In order to specify the value for “K”, one needs to write

the value of “K - 1” (in binary format) into Command

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