mc68hc908gr8vp Freescale Semiconductor, Inc, mc68hc908gr8vp Datasheet - Page 81

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

PRE1 and PRE0 — Prescaler Program Bits
VPR1 and 0 — VCO Power-of-Two Range Select Bits
Freescale Semiconductor
These read/write bits control a prescaler that selects the prescaler power-of-two multiplier, P. (See
7.3.3 PLL Circuits
PLLON bit is set. Reset clears these bits.
These read/write bits control the VCO’s hardware power-of-two range multiplier E that, in conjunction
with L (See
Register.) controls the hardware center-of-range frequency, f
the PLLON bit is set. Reset clears these bits.
if the PLL is off. Therefore, PLLON cannot be cleared when BCS is set, and
BCS cannot be set when PLLON is clear. If the PLL is off (PLLON = 0),
selecting CGMVCLK requires two writes to the PLL control register. (See
7.3.8 Base Clock Selector
The value of P is normally 0 when using a 32.768-kHz crystal as the
reference.
7.3.3 PLL
1. Do not program E to a value of 3.
and
PRE1 and PRE0
VPR1 and VPR0
Circuits,
7.3.6 Programming the
00
01
10
11
00
01
10
11
MC68HC908GR8 • MC68HC908GR4 Data Sheet, Rev. 7
Table 7-2. PRE 1 and PRE0 Programming
Table 7-3. VPR1 and VPR0 Programming
7.3.6 Programming the
Circuit.)
NOTE
PLL.) PRE1 and PRE0 cannot be written when the
3
P
E
0
1
2
3
0
1
2
(1)
PLL, and
VRS
Prescaler Multiplier
VCO Power-of-Two
. VPR1:VPR0 cannot be written when
7.5.5 PLL VCO Range Select
Range Multiplier
1
2
4
8
1
2
4
8
CGMC Registers
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