M16C65 Datasheet, PDF (151/829 Pages) Renesas Technology Corp – RENESAS MCU M16C FAMILY / M16C/60

Under development
M16C/65 Group
Preliminary Specification
This is a preliminary specification and is subject to change.
8. Clock Generator
8.3.3 fOCO40M
The fOCO40M is a 40 MHz clock (approx.), which is supplied by the 40 MHz on-chip oscillator. It is
used as the clock source for φAD of AD converter.
Follow the steps below to start or stop the 40 MHz on-chip oscillator clock. Refer to 8.2 “Registers” for
access to register and bit.
40 MHz on-chip oscillator clock oscillation start
(1) Set the FRA00 bit in the FRA0 register to 1 (40 MHz on-chip oscillator on).
(2) Wait for td (OCOF).
40 MHz on-chip oscillator clock oscillation stop
(1) Set the FRA01 bit in the FRA0 register to 0 (125 MHz on-chip oscillator) (when the CM27 bit is 1
(oscillation stop/re-oscillation detection interrupt)).
(2) Set the FRA00 bit in the FRA0 register to 0 (40 MHz on-chip oscillator off).
8.3.4 fOCO-F
The fOCO-F is a 40 MHz clock (approx.), which is supplied by the 40 MHz on-chip oscillator, divided by
2. It is used as the clock source for the CPU and peripheral function clocks.
After reset, the 40 MHz on-chip oscillator is stopped.
If the main clock stops oscillating and the FRA01 bit is 1 when the CM20 bit in the CM2 register is 1
(oscillation stop/re-oscillation detection function enabled), and the CM27 bit is 1 (oscillation stop/re-
oscillation detection interrupt), the fOCO-F is used as the clock source for the CPU.
Follow the steps below to start or stop the 40 MHz on-chip oscillator clock. Refer to 8.2 “Registers” for
access to registers and bits.
40 MHz on-chip oscillator clock oscillation start
(1) Set the FRA00 bit in the FRA0 register to 1 (40 MHz on-chip oscillator on).
(2) Wait for td (OCOF).
40 MHz on-chip oscillator clock oscillation stop
(1) Set the FRA01 bit in the FRA0 register to 0 (125 MHz on-chip oscillator) (when the CM27 bit is 1
(oscillation stop/re-oscillation detection interrupt)).
(2) Set the FRA00 bit in the FRA0 register to 0 (40 MHz on-chip oscillator off).
REJ09B0484-0030 Rev.0.30 Sep 09, 2008
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