User’s Manual U13850EJ4V0UM
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CHAPTER 6 CLOCK GENERATION FUNCTION
6.1 Outline
The clock generator is a circuit that generates the clock pulses that are supplied to the CPU and peripheral
hardware. There are two types of system clock oscillators.
(1) Main system clock oscillator
The oscillator of V850/SB1 has an oscillation frequency of 2 to 20 MHz. The oscillator of V850/SB2 has an
oscillation frequency of 6 to 12.58 MHz. Oscillation can be stopped by executing a STOP instruction or by setting
the processor clock control register (PCC). Oscillation is also stopped during a reset.
In IDLE mode, supplying the peripheral clock to the clock timer only is possible. Therefore, in IDLE mode, it is
possible to operate the clock timer without using the subsystem clock oscillator.
Cautions 1. When the main oscillator is stopped by inputting a reset or executing a STOP instruction,
the oscillation stabilization time is secured after the stop mode is canceled. This
oscillation stabilization time is set via the oscillation stabilization time selection register
(OSTS). The watchdog timer is used as the timer that counts the oscillation stabilization
time.
2. If the main system clock halt is released by clearing MCK to 0 after the main system clock
is stopped by setting the MCK bit in the PCC register to 1, the oscillation stabilization time
is not secured.
(2) Subsystem clock oscillator
This circuit has an oscillation frequency of 32.768 kHz. Its oscillation is not stopped when the STOP instruction
is executed, neither is it stopped when a reset is input.
When the subsystem clock oscillator is not used, the FRC bit in the processor clock control register (PCC) can
be set to disable use of the internal feedback resistor. This enables the current consumption to be kept low in
the STOP mode.
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