XRT8001 Datasheet, PDF (31/48 Pages) Exar Corporation – WAN Clock for T1 and E1 Systems

XRT8001
8kHz
FIN
CLK1
XRT8001
WAN Clock
L x 56kHz
to
L x 64kHz
1 < L < 32
CLK2
L x 56kHz
to
L x 64kHz
1 < L < 32
Figure 18. Illustration of the XRT8001 WAN Clock operating in the
“Forward/Slave" Mode
6.9 Configuring the XRT8001 WAN Clock into the
“Forward/Slave” Mode.
The user can configure the XRT8001 WAN Clock to
operate in the “Forward/Slave Mode” by executing the
following steps:
Step 1 – Configure the XRT8001 to operate in the
“SLAVE” Mode by pulling the MSB input pin (pin 8) to
GND.
Step 2 – Refer to Table 2B and write the value that
corresponds to the desired "Forward/Slave" Mode into
Bits D[4:1] within Command Register CR0.
Step 3 – Define the values for L, for the CLK1 output
by writing the appropriate value into the CR2 register.
This is achieved by writing the value “L – 1” into this
register.
Notes:
1. For example, if the user writes “00000” into this regis-
ter, then the XRT8001 device will output a 64kHz
signal via the CLK1 output pin.
2. If the user intends to output data via CLK1, then he/she
must ensure that the PL1EN bit-field within Command
Register CR0 is set to “1”.
Step 4- Define the value for L, for the CLK2 output
by writing the appropriate value into the CR3 regis-
ter. This is achieved by writing the value “L – 1”
into this register.
Note: If the user intends to output data via CLK2, then he/
she must ensure that the PL2EN bit-field within Command
Register CR1 is set to “1”.
Step 5 – Set the CLK1EN and CLK2EN bit-fields,
within Command Register CR4 to 1 in order to
enable the output drivers for CLK1 and CLK2, as
illustrated below.
Command Register CR4
D4
D3
D2
D1 D0
SYNCEN CLK1EN CLK2EN
X
X
x
1
1
0
0
Rev. 1.01
31