BS_System controller
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Doc ID 018672 Rev 1
14.4.7 SCXTALCTRL
register
The SCXTALCTRL (crystal control) is a RW register which is used to directly control the
crystal oscillator used to generate the system clock SCLK in both SLOW and NORMAL
mode (
Section 14.3.1: System mode control
). The SCXTALCTRL bit assignments are given
in
.
14.4.8 SCPLLCTRL
register
The SCPLLCTRL (PLL Control) is a RW register which allows the system controller to
directly control the PLL. The SCPLLCTRL bit assignments are given in
Table 236.
SCXTALCTRL register bit assignments
Bit
Name
Type
Reset
value
Description
[31:19]
Reserved
-
-
Read: undefined. Write: should be zero
[18:03]
XtalTime
RW
16’h0
Crystal timeout count
This value is used to define the number of
slow speed oscillator cycles permitted for the
crystal oscillator output to settle after being
enabled. The timeout is given by: 65536 –
XtalTime.
[02]
XtalStat
RO
1’h0
Crystal status bit
This RO bit returns the value on the
XTALON
input signal.
[01]
XtalEn
RW
1’h0
Crystal enable bit
This bit is used to directly control the
XTALEN
output when the crystal control
override is enabled (XtalOver bit set to ‘b1 in
this register).
[00]
XtalOver
RW
1’h0
Crystal control override
If set, this bit enables the crystal control
signals (from system controller) to be placed
under direct software control, rather than
being controlled by the system mode control
state machine.
Table 237.
SCPLLCTRL register bit assignments
Bit
Name
Type
Reset
value
Description
[31:28]
Reserved
-
-
Read: undefined. Write: should be zero
[27:03]
PllTime
RW
25’h0
PLL timeout count
This value is used to define the number of
crystal oscillator cycles permitted for the PLL
output to settle after being enabled.The
timeout value is given by: 33554432 –
PllTime.