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CHAPTER 3 CPU AND CONTROL UNITS
3.11.4
Clock Frequency Division
For each type of internal operation clock signal, the divide ratio relative to the base
clock frequency can be set. This feature allows the optimum operating frequency to be
set for each circuit.
The divide ratio is set by the combination of the DIVR0 (base clock frequency division setting register 0)
and DIVR1 (base clock frequency division setting register 1). Each of the registers has four setting bits for
each type of clock signal. The divide ratio of a clock signal relative to the base clock frequency is
expressed as "the register value for that 1". Even though a divide ratio setting is an odd number,
the duty ratio is always 50%.
When the divide ratio setting is changed, the new setting takes effect at the next rise of the clock signal.
Even when an operation initialization reset (RST) occurs, the divide ratio setting is not initialized but
remains unchanged. It is initialized only at a setting initialization reset (INIT). Before changing the source
clock to a faster one from the initial state, be sure to set the divide ratio.
Note:
If you set a combination of the source clock, main PLL multiplier, and divide ratio, which results in a
frequency higher than the maximum operating frequency, the operation of the device is not
guaranteed. Use meticulous care not to set such a combination of values (in particular, do not select
the source clock and change settings in wrong order).
Summary of Contents for FR60Lite
Page 3: ......
Page 5: ......
Page 115: ...100 CHAPTER 3 CPU AND CONTROL UNITS ...
Page 127: ...112 CHAPTER 4 I O PORTS ...
Page 143: ...128 CHAPTER 5 INTERRUPT CONTROLLER ...
Page 155: ...140 CHAPTER 6 EXTERNAL INTERRUPT AND NMI CONTROLLER ...
Page 197: ...182 CHAPTER 9 PPG Programmable Pulse Generator ...
Page 337: ...322 CHAPTER 13 UART ...
Page 417: ...402 CHAPTER 16 DMAC DMA Controller ...
Page 445: ...430 CHAPTER 17 FLASH MEMORY ...
Page 451: ...436 CHAPTER 18 SERIAL PROGRAMMING CONNECTION ...
Page 493: ...478 APPENDIX F Precautions on Handling ...
Page 494: ...479 INDEX INDEX The index follows on the next page This is listed in alphabetic order ...
Page 507: ...492 INDEX ...
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