MC68HC908GR16 Datasheet, PDF (73/276 Pages) Motorola, Inc – Microcontrollers

CGM Registers
4.5.3 PLL Multiplier Select Register High
The PLL multiplier select register high (PMSH) contains the programming information for the high byte of
the modulo feedback divider.
Address: $0038
Bit 7
6
5
4
3
2
1
Bit 0
Read: 0
0
0
0
MUL11 MUL10 MUL9
MUL8
Write:
Reset: 0
0
0
0
0
0
0
0
= Unimplemented
Figure 4-6. PLL Multiplier Select Register High (PMSH)
MUL11–MUL8 — Multiplier Select Bits
These read/write bits control the high byte of the modulo feedback divider that selects the VCO
frequency multiplier N. (See 4.3.3 PLL Circuits and 4.3.6 Programming the PLL.) A value of $0000 in
the multiplier select registers configures the modulo feedback divider the same as a value of $0001.
Reset initializes the registers to $0040 for a default multiply value of 64.
NOTE
The multiplier select bits have built-in protection such that they cannot be
written when the PLL is on (PLLON = 1).
PMSH[7:4] — Unimplemented Bits
These bits have no function and always read as 0s.
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.
Address: $0038
Bit 7
6
5
4
3
2
1
Bit 0
Read:
MUL7
Write:
MUL6
MUL5
MUL4
MUL3
MUL2
MUL1
MUL0
Reset: 0
1
0
0
0
0
0
0
Figure 4-7. PLL Multiplier Select Register Low (PMSL)
MUL7–MUL0 — Multiplier Select Bits
These read/write bits control the low byte of the modulo feedback divider that selects the VCO
frequency multiplier, N. (See 4.3.3 PLL Circuits and 4.3.6 Programming the PLL.) MUL7–MUL0 cannot
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.
NOTE
The multiplier select bits have built-in protection such that they cannot be
written when the PLL is on (PLLON = 1).
MC68HC908GR16 Data Sheet, Rev. 5.0
Freescale Semiconductor
73