Toshiba TX49 TMPR4937, Manual

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Chapter 6 Clocks
6-5
Table 6.1.4 Relationship Among Different Clock Frequencies (for TMPR4937XBG-333, CPUCLK = 333 MHz)
Master Clock (Input)
and Boot Configured
Settings
Internal Clock External Clock (Output)
SYSCLK (MHz) PCICLK[5:0] (MHz) †
Boot Configured Settings
PCIDIVMODE[2:0]
CCFG Settings
PCIDIVMODE[2:0]
MASTERCLK
(MHz)
Boot
Configured
Setting
ADDR[3:0]
CPUCLK
(MHz)
GBUSCLK
(MHz)
IMBUSCLK
(MHz)
SDCLK
[3:0]
(MHz)
HH
(1/1)
HL
(1/2)
LH
(1/3)
LL
(1/4)
LLH
(1/4)
LHH
(1/4.5)
HLH
(1/5) HHH
(1/5.5)
LLL
(1/8)
LHL
(1/9)
HLL
(1/10)
HHL
(1/11)
-
HHHH(x2.0)
-
HLHH(x8.0)
- - - - - - - - - - - - - - -
133
HHHL (x2.5)
33
HLHL (x10.0)
133 66 133 133 66 44 33
111
HHLH (x3.0)
27
HLLH (x12.0)
111 55 111 111 55 37 27
83
HHLL (x4.0)
20
HLLL (x16.0)
83 41 83 83 41 27 20
74
LHHH(x4.5)
18
LLHH (x18.0)
333
74 37 74 74 37 24 18
83 74 66 60 41 38 33 30
† The CCFG.PCIDIVMODE[2:1] field is setting by the boot configuration ADDR[11:10].
6.2 Power-Down Mode
6.2.1 Halt Mode and Doze Mode
The WAIT instruction causes the TX49/H3 core to enter either of the two low-power modes: Halt and
Doze. The TX49/H3 can exit from Halt or Doze mode upon an interrupt exception. Ensure, therefore,
that the TX49/H3 does not enter Halt or Doze mode when all interrupts are masked in the interrupt
controller.
The HALT bit of the TX49/H3 core Config register is used to select Halt or Doze mode. As the
TX4937 does not use the snoop function of the TX49/H3 core, the bit should be set to select Halt mode,
which achieves greater power reduction than Doze mode.
6.2.2 Power Reduction for Peripheral Modules
When the system does not use the DMA controller, PCI controller, serial I/O controller,
timers/counters, parallel I/O controller, or AC-link controller, it can stop the input clock for that module
to reduce power dissipation.
The clock control register (CLKCTR) is used to control whether to turn each clock on or off. The
module should be reset before its clock can be turned on or off. This reset is performed using the reset
bit for the specific module, provided in the clock control register. The reset also initializes the registers
of the module, thus requiring subsequent setup of necessary register values and other configurations.
Refer to Section 5.2.5, "Clock Control Register" for detail of the clock control register (CLKCTR).