uPD789074 Subseries 8-Bit Single-Chip Microcontrollers UD - Home

CHAPTER 5 CLOCK GENERATOR5.1 Clock Generator FunctionsThe clock generator generates the clock to be supplied to the CPU and peripheral hardware.• Expanded-specification productsThe system oscillator oscillates a frequency of 1.0 to 10.0 MHz. Oscillation can be stopped by executing theSTOP instruction.• Conventional productsThe system oscillator oscillates a frequency of 1.0 to 5.0 MHz. Oscillation can be stopped by executing theSTOP instruction.5.2 Clock Generator ConfigurationThe clock generator includes the following hardware.Table 5-1. Configuration of Clock GeneratorItemConfigurationControl registerOscillatorProcessor clock control register (PCC)Crystal/ceramic oscillatorFigure 5-1. Block Diagram of Clock GeneratorPrescalerX1X2System clockoscillatorSTOPfXClock to peripheralhardwarePrescalerfX2 2SelectorStandbycontrollerWaitcontrollerCPU clock (fCPU)PCC1Processor clock controlregister (PCC)Internal busUser’s Manual U14801EJ3V1UD 75