MC56F8345 Freescale Semiconductor, Inc, MC56F8345 Datasheet - Page 38

• Manufacturer Part Number: MC56F8345
• Description: 56f8300 16-bit Digital Signal Controllers
• Manufacturer: Freescale Semiconductor, Inc

Note:
3.2.3
The recommended method of connecting an external clock is illustrated in
source is connected to XTAL and the EXTAL pin is grounded.
external clock source as well.
3.3 Registers
When referring to the register definitions for the OCCS in the 56F8300 Peripheral User Manual, use the
register definitions without the internal Relaxation Oscillator, since the 56F8345/56F8145 devices do
NOT contain this oscillator.
Part 4 Memory Map
4.1 Introduction
The 56F8345 and 56F8145 devices are 16-bit motor-control chips based on the 56800E core. These parts
use a Harvard-style architecture with two independent memory spaces for Data and Program. On-chip
38
2 Terminal
CL1
The OCCS_COHL bit must be set to 0 when a ceramic resonator 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’s Manual.
External Clock Source
EXTAL XTAL
Figure 3-4 Connecting an External Clock Signal Register
R
z
CL2
Figure 3-3 Connecting a Ceramic Resonator
Resonator Frequency = 4 - 8MHz (optimized for 8MHz)
External
XTAL
Clock
3 Terminal
C1
EXTAL XTAL
56F8345 Technical Data, Rev. 17
EXTAL
V
R
SS
z
C2
Note: When using an external clocking
source with this configuration, the input
“CLKMODE” should be high and COHL bit in
the OSCTL register should be set to 1.
Sample External Ceramic Resonator Parameters:
R
z
= 750 KΩ
Set OCCS_COHL bit high when using an
CLKMODE = 0
Figure
3-4. The external clock
Freescale Semiconductor
Preliminary