ST7MC1 datasheet(35/308 Pages) STMICROELECTRONICS

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ST7MC1/ST7MC2

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SYSTEM INTEGRITY MANAGEMENT (Cont’d)

SYSTEM INTEGRITY (SI) CONTROL/STATUS REGISTER (SICSR, page 1)

Reset Value: 00000000 (00h)

Bit 7 = PAGE SICSR Register Page Selection

This bit selects the SICSR register page. It is set

and cleared by software

0: Access to SICSR register mapped in page 0.

1: Access to SICSR register mapped in page 1.

Bit 6 = Reserved, must be kept cleared.

Bit 5 = VCOEN VCO Enable

This bit is set and cleared by software.

0: VCO (Voltage Controlled Oscillator) connected

to the output of the PLL charge pump (default

mode), to obtain a 16-MHz output frequency

(with an 8-MHz input frequency).

1: VCO tied to ground in order to obtain a 10-MHz

frequency (fvco)

Notes:

1. During ICC session, this bit is set to 1 in order to

have an internal frequency which does not depend

on the input clock. Then, it can be reset in order to

run faster with an external oscillator.

Bit 4 = LOCK PLL Locked

This bit is read only. It is set by hardware. It is set

automatically when the PLL reaches its operating

frequency.

0: PLL not locked

1: PLL locked

Bit 3 = PLLEN PLL Enable

This bit enables the PLL and the clock detector. It

is set and cleared by software.

0: PLL and Clock Detector (CKD) disabled

1: PLL and Clock Detector (CKD) enabled

Notes:

1. During ICC session, this bit is set to 1.

2. PLL cannot be disabled if PLL clock source is

selected (CKSEL= 1).

Bit 2 = Reserved, must be kept cleared.

Bit 1 = CKSEL Clock Source Selection

This bit selects the clock source: oscillator clock or

clock from the PLL. It is set and cleared by soft-

ware. It can also be set by option byte (PLL opt)

0: Oscillator clock selected

1: PLL clock selected

Notes:

1. During ICC session, this bit is set to 1. Then,

CKSEL can be reset in order to run with fOSC.

2. Clock from the PLL cannot be selected if the

PLL is disabled (PLLEN =0)

3. If the clock source is selected by PLL option bit,

CKSEL bit selection has no effect.

Bit 0 = Reserved, must be kept cleared.

VCO

PLL

CK-

SEL

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