mc68hc908qz16 Freescale Semiconductor, Inc, mc68hc908qz16 Datasheet - Page 73

• Manufacturer Part Number: mc68hc908qz16
• Description: M68hc08 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

4.5.4 PLL Multiplier Select Register Low
The PLL multiplier select register low (PMSL) contains the programming information for the low byte of
the modulo feedback divider.
MUL7–MUL0 — Multiplier Select Bits
4.5.5 PLL VCO Range Select Register
The PLL VCO range select register (PMRS) contains the programming information required for the
hardware configuration of the VCO.
Freescale Semiconductor
These read/write bits control the low byte of the modulo feedback divider that selects the VCO
frequency multiplier, N. (See
be written when the PLLON bit in the PCTL is set. A value of $0000 in the multiplier select registers
configures the modulo feedback divider the same as a value of $0001. Reset initializes the register to
$40 for a default multiply value of 64.
Address:
Address:
For applications using 1–8 MHz reference frequencies this register must be
reprogrammed before enabling the PLL. The reset value of this register will
cause applications using 1–8 MHz reference frequencies to become
unstable if the PLL is enabled without programming an appropriate value.
The programmed value must not allow the VCO clock to exceed 32 MHz.
See
proper value for PMSL.
The multiplier select bits have built-in protection such that they cannot be
written when the PLL is on (PLLON = 1).
PMRS may be called PVRS on other HC08 derivatives.
Reset:
Reset:
Read:
Read:
Write:
Write:
4.3.6 Programming the PLL
$003A
$0038
Figure 4-7. PLL Multiplier Select Register Low (PMSL)
MUL7
VRS7
Bit 7
Bit 7
Figure 4-8. PLL VCO Range Select Register (PMRS)
0
0
MC68HC908GZ16 • MC68HC908GZ8 Data Sheet, Rev. 4
4.3.3 PLL Circuits
MUL6
VRS6
6
1
6
1
MUL5
VRS5
5
0
5
0
for detailed instructions on choosing the
NOTE
NOTE
NOTE
and
MUL4
VRS4
4
0
4
0
4.3.6 Programming the
MUL3
VRS3
3
0
3
0
MUL2
VRS2
2
0
2
0
MUL1
VRS1
PLL.) MUL7–MUL0 cannot
1
0
1
0
MUL0
VRS0
Bit 0
Bit 0
0
0
CGM Registers
73