Internal Clock Source (S08ICSV3)

 

Table 12-5. ICSTRM Field Descriptions

 

 

Field

Description

 

 

7:0

ICS Trim Setting. The TRIM bits control the internal reference clock frequency by controlling the internal

TRIM

reference clock period. The bits’ affects are binary weighted (bit 1 adjusts twice as much as bit 0). Increasing the

 

binary value in TRIM increases the period and decreasing the value decreases the period.

 

An additional fine trim bit is available in ICSSC as the FTRIM bit.

 

 

12.3.4ICS Status and Control (ICSSC)

R

W

Reset:

7

6

5

4

3

2

1

0

 

DRST

DMX32

IREFST

 

CLKST

OSCINIT

FTRIM1

 

 

 

 

 

 

 

DRS

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

0

0

0

1

0

0

0

 

Figure 12-6. ICS Status and Control Register (ICSSC)

1FTRIM is loaded during reset from a factory programmed location when not in any BDM mode. If in a BDM mode, FTRIM gets loaded with a value of 1’b0.

 

 

Table 12-6. ICSSC Field Descriptions

 

 

 

Field

 

Description

 

 

7-6

DCO Range Status. The DRST read field indicates the current frequency range for the FLL output, DCOOUT.

DRST

See Table 12-7. The DRST field does not update immediately after a write to the DRS field due to internal

DRS

synchronization between clock domains. Writing the DRS bits to 2’b11 is ignored and the DRST bits remain with

 

the current setting.

 

DCO Range Select. The DRS field selects the frequency range for the FLL output, DCOOUT. Writes to the DRS

 

field while the LP bit is set are ignored.

 

00

Low range.

 

01

Mid range.

 

10

High range.

 

11

Reserved.

 

 

5

DCO Maximum Frequency with 32.768 kHz Reference. The DMX32 bit controls whether or not the DCO

DMX32

frequency range is narrowed to its maximum frequency with a 32.768 kHz reference. See Table 12-7.

 

0

DCO has default range of 25%.

 

1

DCO is fined tuned for maximum frequency with 32.768 kHz reference.

 

 

4

Internal Reference Status. The IREFST bit indicates the current source for the reference clock. The IREFST bit

IREFST

does not update immediately after a write to the IREFS bit due to internal synchronization between clock

 

domains.

 

0 Source of reference clock is external clock.

 

1 Source of reference clock is internal clock.

 

 

3-2

Clock Mode Status. The CLKST bits indicate the current clock mode. The CLKST bits don’t update immediately

CLKST

after a write to the CLKS bits due to internal synchronization between clock domains.

 

00

Output of FLL is selected.

 

01

FLL Bypassed, Internal reference clock is selected.

 

10

FLL Bypassed, External reference clock is selected.

 

11

Reserved.

 

 

 

 

 

MCF51QE128 MCU Series Reference Manual, Rev. 3

 

 

 

252

 

Freescale Semiconductor

 

 

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Freescale Semiconductor MCF51QE128RM ICS Status and Control Icssc, Icstrm Field Descriptions, Icssc Field Descriptions