System Control Registers
228
SPRUHE8E – October 2012 – Revised November 2019
Copyright © 2012–2019, Texas Instruments Incorporated
System Control and Interrupts
Table 1-110. Master Subsystem Clock Divider (M3SSDIVSEL) Register Field Descriptions
Bit
Field
Value
Description
31-2
Reserved
Reserved
1-0
M3SSDIVSEL
M3 Subsystem Clock Divide
This bit selects between /4, /2, and /1 for the M3 sub-system clock. The C28 CLKIN clock is divided
by the below ratios to generate the M3 SS clock. The configuration of the M3SSDIVSEL bits is as
follows.
00
Select M3SS clock divide By 1 of PLLYSCLK clock
01
Select M3SS clock divide By 2 of PLLYSCLK clock
10
Select M3SS clock divide By 4 of PLLSYSCLK clock
11
Reserved
1.13.7.5 XPLL CLKOUT Control (XPLLCLKCFG) Register
Figure 1-100. XPLL CLKOUT Control (XPLLCLKCFG) Register
31
2
1
0
Reserved
XPLLCLKOUTDIV
R-0:0
R/W-11
LEGEND: R/W = Read/Write; R = Read only; -
n
= value after reset
Table 1-111. XPLL CLKOUT Control (XPLLCLKCFG) Register Field Descriptions
Bit
Field
Value
Description
31-2
Reserved
Reserved
1-0
XPLLCLKOUTDI
V
XPLLCLKOUT Divide Ratio
This bit selects a clock divide ratio for the XPLLCLKOUT clock. The configuration of the
XPLLCLKOUTDIV bits is as follows.
00
XPLLCLKOUT is off
01
Select XPLLCLKOUT = SYSCLK/4
10
Select XPLLCLKOUT = M3 SSCLK/4
11
Select XPLLCLKOUT = PLLSYSCLK/4 (default)
1.13.7.6 USB PLL Configuration (UPLLCTL) Register
Figure 1-101. USB PLL Configuration (UPLLCTL) Register
31
3
2
1
0
Reserved
UPLLCLKEN
UPLLEN
R-0:0
R/W-0
R/W-0
R/W-0
LEGEND: R/W = Read/Write; R = Read only; -
n
= value after reset
Table 1-112. USB PLL Configuration (UPLLCTL) Register Field Descriptions
Bit
Field
Value
Description
31-3
Reserved
Reserved
2
UPLLCLKEN
USB PLL Clock Enable
USB PLL bypassed or included in the USB clock path.
This bit decides if the USB PLL is bypassed to supply the 60-MHz clock to the USB
Note:
The PLL bypass option can be used only with GPIO_XCLKIN as a clock source to the USB
because the oscillators will support only up to a 20 MHz input clock
0
USB PLL is bypassed; clock to the USB is direct feed from GPIO_XCLKIN.
1
USB PLL is on the clock path to USBCLK and it is the PLL multiplied clock.