mc68hc908gr8vp Freescale Semiconductor, Inc, mc68hc908gr8vp Datasheet - Page 75

• Manufacturer Part Number: mc68hc908gr8vp
• Description: M68hc08 Microcontrollers Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

Table 7-1
Freescale Semiconductor
10. Verify the choice of P, R, N, E, and L by comparing f
11. Program the PLL registers accordingly:
9. Calculate and verify the adequacy of the VCO programmed center-of-range frequency, f
center-of-range frequency is the midpoint between the minimum and maximum frequencies
attainable by the PLL.
For proper operation,
operation, f
as possible to f
a. In the PRE bits of the PLL control register (PCTL), program the binary equivalent of P.
b. In the VPR bits of the PLL control register (PCTL), program the binary equivalent of E.
d. In the PLL VCO range select register (PMRS), program the binary coded equivalent of L.
e. In the PLL reference divider select register (PMDS), program the binary coded equivalent
c. In the PLL multiplier select register low (PMSL) and the PLL multiplier select register high
provides numeric examples (numbers are in hexadecimal notation):
(PMSH), program the binary equivalent of N.
of R.
Exceeding the recommended maximum bus frequency or VCO frequency
can crash the MCU.
VCLK
2.4576 MHz
4.9152 MHz
7.3728 MHz
2.0 MHz
2.5 MHz
4.0 MHz
5.0 MHz
8.0 MHz
f
VCLK
BUS
must be within the application’s tolerance of f
.
MC68HC908GR8 • MC68HC908GR4 Data Sheet, Rev. 7
Table 7-1. Numeric Example
32.768 kHz
32.768 kHz
32.768 kHz
32.768 kHz
32.768 kHz
32.768 kHz
32.768 kHz
32.768 kHz
f
VRS
f
f
RCLK
VRS
–
f
=
VCLK
NOTE
(
L
×
≤
2
E
f
--------------------------
NOM
)f
R
1
1
1
1
1
1
1
1
NOM
2
VCLK
×
2
E
12C
1E9
3D1
132
258
263
384
to f
F5
N
VRS
VCLKDES
and f
P
0
0
0
0
0
0
0
0
, and f
VCLKDES
E
0
1
1
1
2
2
2
2
VRS
Functional Description
. For proper
D1
D1
C0
D0
80
83
80
82
L
must be as close
VRS
. The
75