MC908QL4 FREESCALE [Freescale Semiconductor, Inc], MC908QL4 Datasheet - Page 119

• Manufacturer Part Number: MC908QL4
• Description: M68HC08 Microcontrollers
• Manufacturer: FREESCALE [Freescale Semiconductor, Inc]

13.2 RST and IRQ Pins Initialization
RST and IRQ pins come out of reset as PTA3 and PTA2 respectively. RST and IRQ functions can be
activated by programing CONFIG2 accordingly. Refer to
13.3 SIM Bus Clock Control and Generation
The bus clock generator provides system clock signals for the CPU and peripherals on the MCU. The
system clocks are generated from an incoming clock, BUSCLKX2, as shown in
13.3.1 Bus Timing
In user mode, the internal bus frequency is the oscillator frequency (BUSCLKX4) divided by four.
13.3.2 Clock Start-Up from POR
When the power-on reset module generates a reset, the clocks to the CPU and peripherals are inactive
and held in an inactive phase until after the 4096 BUSCLKX4 cycle POR time out has completed. The
IBUS clocks start upon completion of the time out.
13.3.3 Clocks in Stop Mode and Wait Mode
Upon exit from stop mode by an interrupt or reset, the SIM allows BUSCLKX4 to clock the SIM counter.
The CPU and peripheral clocks do not become active until after the stop delay time out. This time out is
selectable as 4096 or 32 BUSCLKX4 cycles. See
In wait mode, the CPU clocks are inactive. The SIM also produces two sets of clocks for other modules.
Refer to the wait mode subsection of each module to see if the module is active or inactive in wait mode.
Some modules can be programmed to be active in wait mode.
Freescale Semiconductor
OSCILLATOR
OSCILLATOR
FROM
FROM
Figure 13-2. SIM Clock Signals
MC68HC908QL4 Data Sheet, Rev. 7
BUSCLKX4
BUSCLKX2
13.7.2 Stop
÷
SIM COUNTER
Chapter 5 Configuration Register
2
SIM
Mode.
GENERATORS
BUS CLOCK
RST and IRQ Pins Initialization
Figure
13-2.
(CONFIG).
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