PIC18F4550_Oscillator_Architecture - 2.0 2.1 OSCILLATOR...

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2.0 OSCILLATOR CONFIGURATIONS 2.1 Overview Devices in the PICI8F2455125501445514550 family incorporate a different oscillator and microcontroller clock system than previous PIC1 8F devices. The addi- tion of the USB module, with its unique requirements for a stable clock source, make it necessary to provide a separate clock source that is compliant with both USB low-speed and full-speed specifications. To accommodate these requirements, PIC1 8F24551 25501445514550 devices include a new clock branch to provide a 48 MHz clock for full-speed USB operation. Since it is driven from the primary clock source, an additional system of prescalers and postscalers has been added to accommodate a wide range of oscillator frequencies. An overview of the oscillator structure is shown in Figure 2-1. Other oscillator features used in PIC18 enhanced microcontrollers, such as the internal oscillator block and clock switching, remain the same. They are discussed later in this chapter. 2.1.1 OSCILLATOR CON'rROL The operation of the oscillator in PIC18F2455125501 445514550 devices is controlled through two Configu- ration registers and two control registers. Configuration
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This note was uploaded on 03/11/2012 for the course E E 316 taught by Professor Ridiggio during the Spring '11 term at Penn State.

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PIC18F4550_Oscillator_Architecture - 2.0 2.1 OSCILLATOR...

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