NXP Semiconductors MC9S08LG16, Reference Manual

Page: 91 / 373

Chapter 5 Resets, Interrupts, and General System Control
MC9S08LG32 MCU Series, Rev. 5
Freescale Semiconductor 91
5.8.10 System Clock Gating Control 2 Register (SCGC2)
This high-page register contains control bits to enable or disable the bus clock to the IRQ, KBI, LCD, and
SPI 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 must 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.
7 6 5 4 3 2 1 0
R
DBG FLS IRQ KBI
0 0
LCD SPI
W — —
Reset: 0 1 0 0 0 0 0 0
= Unimplemented or Reserved
Figure 5-12. System Clock Gating Control 2 Register (SCGC2)
Table 5-14. SCGC2 Register Field Descriptions
Field Description
7
DBG
DBG Register Clock Gate Control — This bit controls the bus clock gate to the DBG module.
0 Bus clock to the DBG module is disabled.
1 Bus clock to the DBG module is enabled.
6
FLS
Flash Clock Gate Control — This bit controls the bus clock gate to the Flash module.
0 Bus clock to the Flash module is disabled.
1 Bus clock to the Flash module is enabled.
5
IRQ
IRQ Clock Gate Control — This bit controls the bus clock gate to the IRQ module.
0 Bus clock to the IRQ module is disabled.
1 Bus clock to the IRQ module is enabled.
4
KBI
KBI Clock Gate Control — This bit controls the clock gate to the KBI module.
0 Bus clock to the KBI module is disabled.
1 Bus clock to the KBI module is enabled.
1
LCD
LCD Clock Gate Control — This bit controls the bus clock gate to the LCD module. Only the bus clock is gated,
the OSCOUT, TODCLK and LPOCLK are still available to the LCD.
0 Bus clock to the LCD module is disabled.
1 Bus clock to the LCD module is enabled.
0
SPI
SPI Clock Gate Control — This bit controls the clock gate to the SPI module.
0 Bus clock to the SPI module is disabled.
1 Bus clock to the SPI module is enabled.