Chapter 5 Resets, Interrupts, and General System Control
MC9S08QE128 MCU Series Reference Manual, Rev. 2
108
Freescale Semiconductor
5.8.11
System Clock Gating Control 2 Register (SCGC2)
This high page register contains control bits to enable or disable the bus clock to the RTC and SPIx
modules. Gating off the clocks to unused peripherals is used to reduce the MCU’s run and wait currents.
See
Section 5.7, “Peripheral Clock Gating
,” for more information.
NOTE
User software should disable the peripheral before disabling the clocks to
the peripheral. When clocks are re-enabled to a peripheral, the peripheral
registers need to be re-initialized by user software.
Table 5-14. SCGC1 Register Field Descriptions
Field
Description
7
TPM3
TPM3 Clock Gate Control — This bit controls the clock gate to the TPM3 module.
0 Bus clock to the TPM3 module is disabled.
1 Bus clock to the TPM3 module is enabled.
6
TPM2
TPM2 Clock Gate Control — This bit controls the clock gate to the TPM2 module.
0 Bus clock to the TPM2 module is disabled.
1 Bus clock to the TPM2 module is enabled.
5
TPM1
TPM1 Clock Gate Control — This bit controls the clock gate to the TPM1 module.
0 Bus clock to the TPM1 module is disabled.
1 Bus clock to the TPM1 module is enabled.
4
ADC
ADC Clock Gate Control — This bit controls the clock gate to the ADC module.
0 Bus clock to the ADC module is disabled.
1 Bus clock to the ADC module is enabled.
3
IIC2
IIC2 Clock Gate Control — This bit controls the clock gate to the IIC2 module.
0 Bus clock to the IIC2 module is disabled.
1 Bus clock to the IIC2 module is enabled.
2
IIC1
IIC1 Clock Gate Control — This bit controls the clock gate to the IIC1 module.
0 Bus clock to the IIC1 module is disabled.
1 Bus clock to the IIC1 module is enabled.
1
SCI2
SCI2 Clock Gate Control — This bit controls the clock gate to the SCI2 module.
0 Bus clock to the SCI2 module is disabled.
1 Bus clock to the SCI2 module is enabled.
0
SCI1
SCI1 Clock Gate Control — This bit controls the clock gate to the SCI1 module.
0 Bus clock to the SCI1 module is disabled.
1 Bus clock to the SCI1 module is enabled.
7
6
5
4
3
2
1
0
R
DBG
FLS
IRQ
KBI
ACMP
RTC
SPI2
SPI1
W
Reset:
1
1
1
1
1
1
1
1
= Unimplemented or Reserved
Figure 5-13. System Clock Gating Control 2 Register (SCGC2)
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