mcf51ac256a Freescale Semiconductor, Inc, mcf51ac256a Datasheet - Page 379

• Manufacturer Part Number: mcf51ac256a
• Description: Mcf51ac Flexis
• Manufacturer: Freescale Semiconductor, Inc

16.3.7
Freescale Semiconductor
DMX32
DRST
Field
Field
DRS
7:6
4:2
1:0
7:6
4:1
5
5
0
MCG Test Register (MCGT)
Reserved for test, user code should not write 1’s to these bits.
DCO Maximum frequency with 32.768 kHz reference — The DMX32 bit controls whether or not the DCO
frequency range is narrowed to its maximum frequency with a 32.768 kHz reference. See
0 DCO has default range of 25%.
1 DCO is fined tuned for maximum frequency with 32.768 kHz reference.
Reserved for test, user code should not write 1’s to these bits.
DCO Range Status — The DRST read bits indicate the current frequency range for the FLL output, DCOOUT.
See
synchronization between clock domains. The DRST bits are not valid in BLPI, BLPE, PBE or PEE mode and it
reads zero regardless of the DCO range selected by the DRS bits.
DCO Range Select — The DRS bits select the frequency range for the FLL output, DCOOUT. Writes to the DRS
bits while either the LP or PLLS bit is set are ignored.
00Low range.
01Mid range.
10High range.
11Reserved
Reserved for test, user code should not write 1’s to these bits.
Reserved, user code should not write 1’s to these bits
Reserved for test, user code should not write 1’s to these bits.
Reserved, user code should not write 1’s to these bits
Table
1
DRS DMX32
MCF51AC256 ColdFire Integrated Microcontroller Reference Manual, Rev. 5
The resulting bus clock frequency should not exceed the maximum specified bus
clock frequency of the device.
00
01
10
11
16-9. The DRST bits do not update immediately after a write to the DRS field due to internal
Table 16-8. MCG Test and Control Register Field Descriptions
Table 16-10. MCG Test Register Field Descriptions
0
1
0
1
0
1
31.25 - 39.0625 kHz
31.25 - 39.0625 kHz
31.25 - 39.0625 kHz
Table 16-9. DCO frequency range
Reference range
32.768 kHz
32.768 kHz
32.768 kHz
Reserved
Description
Description
FLL factor
1024
1216
1536
1824
512
608
1
Multipurpose Clock Generator (MCGV3)
DCO range
16 - 20 MHz
32 - 40 MHz
48-60 MHz
59.77 MHz
19.92 MHz
39.85 MHz
Table
16-9.
16-11