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MC9S08GT16A Datasheet, PDF (22/300 Pages) Freescale Semiconductor, Inc – Microcontrollers | |||
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Device Overview
Some of the modules inside the MCU have clock source choices. Figure 1-2 shows a simpliï¬ed clock
connection diagram. The ICG supplies the clock sources:
⢠ICGOUT is an output of the ICG module. It is one of the following:
â The external crystal oscillator
â An external clock source
â The output of the digitally-controlled oscillator (DCO) in the frequency-locked loop
sub-module
Control bits inside the ICG determine which source is connected.
⢠FFE is a control signal generated inside the ICG. If the frequency of ICGOUT > 4 à the frequency
of ICGERCLK, this signal is a logic 1 and the ï¬xed-frequency clock will be the ICGERCLK.
Otherwise the ï¬xed-frequency clock will be BUSCLK.
⢠ICGLCLK â Development tools can select this internal self-clocked source (~ 8 MHz) to speed
up BDC communications in systems where the bus clock is slow.
⢠ICGERCLK â External reference clock can be selected as the real-time interrupt clock source.
MC9S08GT16A/GT8A Data Sheet, Rev. 1
22
Freescale Semiconductor
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