MC56F8323EVM Freescale Semiconductor, MC56F8323EVM Datasheet - Page 30

• Manufacturer Part Number: MC56F8323EVM
• Description: KIT EVALUATION FOR MC56F8323
• Manufacturer: Freescale Semiconductor
• Type: DSPr

Specifications of MC56F8323EVM

• Contents: Module and Misc Hardware
• Processor To Be Evaluated: MC56F8322 and MC56F8323
• Data Bus Width: 16 bit
• Interface Type: RS-232
• For Use With/related Products: MC56F8322, MC56F8323
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

Part 3 On-Chip Clock Synthesis (OCCS)
3.1 Introduction
Refer to the OCCS chapter of the 56F8300 Peripheral User Manual for a full description of the OCCS.
The material contained here identifies the specific features of the OCCS design.
3.2 External Clock Operation
The system clock can be derived from an external crystal, ceramic resonator, or an external system clock
signal. To generate a reference frequency using the internal oscillator, a reference crystal or ceramic
resonator must be connected between the EXTAL and XTAL pins.
3.2.1
The internal oscillator is designed to interface with a parallel-resonant crystal resonator in the frequency
range specified for the external crystal in
in
parameters determine the component values required to provide maximum stability and reliable start-up.
The crystal and associated components should be mounted as near as possible to the EXTAL and XTAL
pins to minimize output distortion and start-up stabilization time.
Note:
3.2.2
It is also possible to drive the internal oscillator with a ceramic resonator, assuming the overall system
design can tolerate the reduced signal integrity. A typical ceramic resonator circuit is shown in
Refer to the supplier’s recommendations when selecting a ceramic resonator and associated components.
The resonator and components should be mounted as near as possible to the EXTAL and XTAL pins.
30
Figure
CLKMODE = 0
3-1. Follow the crystal supplier’s recommendations when selecting a crystal, since crystal
Crystal Oscillator
The OCCS_COHL bit should be set to 1 when a crystal oscillator is used. The reset condition on the
OCCS_COHL bit is 0. Please see the COHL bit in the Oscillator Control (OSCTL) register, discussed
in the 56F8300 Peripheral User Manual.
Ceramic Resonator (Default)
CL1
EXTAL XTAL
R
Figure 3-1 Connecting to a Crystal Oscillator
z
Crystal Frequency = 4 - 8MHz (optimized for 8MHz)
CL2
EXTAL XTAL
56F8323 Technical Data, Rev. 17
Table
R
z
10-15. A recommended crystal oscillator circuit is shown
Sample External Crystal Parameters:
R
Note: If the operating temperature range is limited to
below 85
z
= 750 KΩ
o
C (105
o
C junction), then R
Freescale Semiconductor
z
= 10 Meg Ω
Figure
Preliminary
3-2.