CLPMCR0 REG
C28CPUCLK
C28NMIINT
TIMER 0
execution of IDLE instruction
activates the IDLES signal
ENTER
IDLE
MODE
ENTER
STANDBY
MODE
EXIT
IDLE
MODE
EXIT
STANDBY
MODE
IDLES
LPM(0)
LPM(1)
R
e
q
u
e
st
s
T
o
W
a
k
e
F
ro
m
S
T
A
N
D
B
Y
M
o
d
e
R
e
q
u
e
st
s
T
o
W
a
ke
F
ro
m
ID
LE
M
o
d
e
TINT2
TIMER 2
C28 XINT(3)
C28x NMI
EPWM (12)
C28 DMA
C28CLKENBx
LOSPCP REG
ECAP (6)
I C
2
C28LSPCLK
C28x CPU
‘0’
C28CLKIN
MASTER SUBSYSTEM
STANDBY
MODE
PLLSYSCLK
LPMWAKE
/32
/1
/2
/4
…
/14
MTOCIPC(1)
IPC
LSPCLK
CLOCKFAIL
TIMER 1
TINT 1
C28x NMI
EQEP (3)
GPIO_MUX1
SCI
SPI
McBSP
T
M
R
2
C
LK
PCLKCR3 REG
PCLKCR1 REG
PCLKCR0 REG
10MHZCLK
C28x
PIE
PIEINTRS (1)
OSCCLK
/1
/2
/4
/8
/16
OSCCLK
C28SYSCLK
10MHZCLK
CTMR2CLK
PRESCALE
TMR2CLKSRCSEL
CLKCTL REG
C28SYSCLK
GPIO_MUX1
PULSE
STRETCH
S
O
C
A
O
S
O
C
B
O
S
Y
N
C
O
OFF
/1
/2
/4
/8
CCLKCTL REG
CLKDIV
ASYSCLK
A
N
A
LO
G
S
U
B
S
Y
S
T
E
M
SRXRST
ACIBRST
ASYSRST
C28x
PIE
PIEINTRS (12:1)
C28 FPU/VCU
CLPMSTAT REG
C28SYSCLK
LPM WAKEUP
LPMSEL1 REG
LPMSEL2 REG
SELECT QUALIFICATION
SELECT ONE OF 62 GPIs
SYSPLLSTAT REG
SYSPLLMULT REG
SYSPLLCTL REG
SYSDIVSEL REG
CCLKREQUEST REG
M3SSCLK
GPI (63:0)
CLKOFF REG
GPIO_MUX1
/4
XCLKOUT
P
F
2
_
G
P
IO
3
4
C28SYSCLK
C28SYSCLK
0
1
2
3
XPLLCLKCFG REG
XPLLCLKOUTDIV
OFF
/4
/2
/1
OFF
CXCLK REG
XCLKOUTDIV
(NOTE: IN REVISION 0 OF SILICON, XCLKOUT = PLLSYSCLK DIVIDED DOWN BY 1, 2 OR 4)
C28SYSCLK
C28x must control pin
M3 must
control pin
Clock Control
131
SPRUH22I – April 2012 – Revised November 2019
Copyright © 2012–2019, Texas Instruments Incorporated
System Control and Interrupts
Figure 1-12. Control Subsystem Clocks and Low Power Mode Configuration
1.8.4.1
C28x Normal Mode
In normal mode, the C28x processor, most memory, and most of the peripherals are clocked by the
C28SYSCLK, which is derived from the C28CLKIN input clock to the C28x processor. The remainder of
the memories, FPU, VCU, PIE, and three timers are clocked by C28CPUCLK, which is also derived from
the C28CLKIN. Timer 2 can be clocked by TMR2CLK, which is a divided-down version of one of three
source clocks: C28SYSCLK, OSCCLK, or 10 MHZCLK as selected by the CLKCTL register.
Additionally, the LOSPCP register can be programmed to provide a low-speed clock (C28LSPCLK) to the
SCI, SPI, and McBSP peripherals. Clock gating for individual peripherals is defined inside the
PCLKCR0,1, and 3 registers. Execution of the IDLE instruction stops the C28x processor from clocking
and activates the IDLES signal. The IDLES signal is gated with two LPM bits of the CLPMCR0 register to
enter the control subsystem into idle mode or standby mode.
Refer to
for more details on these registers.