CD00001237 datasheet(16/105 Pages) STMICROELECTRONICS

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ST6215C ST6225C

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3.3 OPTION BYTES

Each device is available for production in user pro-

grammable versions (OTP) as well as in factory

coded versions (ROM). OTP devices are shipped

to customers with a default content (00h), while

ROM factory coded parts contain the code sup-

plied by the customer. This implies that OTP de-

vices have to be configured by the customer using

the Option Bytes while the ROM devices are facto-

ry-configured.

The two option bytes allow the hardware configu-

ration of the microcontroller to be selected.

The option bytes have no address in the memory

map and can be accessed only in programming

mode (for example using a standard ST6 program-

ming tool).

In masked ROM devices, the option bytes are

fixed in hardware by the ROM code (see Section

12.6.2 "ROM Version" on page 98). It is therefore

impossible to read the option bytes.

The option bytes can be only programmed once. It

is not possible to change the selected options after

they have been programmed.

In order to reach the power consumption value in-

dicated in Section 11.4, the option byte must be

programmed to its default value. Otherwise, an

over-consumption will occur.

MSB OPTION BYTE

Bits 15:10 = Reserved, must be always cleared.

Bit 9 = EXTCNTL External STOP MODE control.

0: EXTCNTL mode not available. STOP mode is

not available with the watchdog active.

1: EXTCNTL mode available. STOP mode is avail-

able with the watchdog active by setting NMI pin

to one.

Bit 8 = LVD Low Voltage Detector on/off.

This option bit enable or disable the Low Voltage

Detector (LVD) feature.

0: Low Voltage Detector disabled

1: Low Voltage Detector enabled.

LSB OPTION BYTE

Bit 7 = PROTECT Readout Protection.

This option bit enables or disables external access

to the internal program memory.

0: Program memory not read-out protected

1: Program memory read-out protected

Bit 6 = OSC Oscillator selection.

This option bit selects the main oscillator type.

0: Quartz crystal, ceramic resonator or external

clock

1: RC network

Bits 5:4 = Reserved, must be always cleared.

Bit 3 = NMI PULL NMI Pull-Up on/off.

This option bit enables or disables the internal pull-

up on the NMI pin.

0: Pull-up disabled

1: Pull-up enabled

Bit 2 = TIM PULL TIMER Pull-Up on/off.

This option bit enables or disables the internal pull-

up on the TIMER pin.

0: Pull-up disabled

1: Pull-up enabled

Bit 1 = WDACT Hardware or software watchdog.

This option bit selects the watchdog type.

0: Software (watchdog to be enabled by software)

1: Hardware (watchdog always enabled)

Bit 0 = OSGEN Oscillator Safeguard on/off.

This option bit enables or disables the oscillator

Safeguard (OSG) feature.

0: Oscillator Safeguard disabled

1: Oscillator Safeguard enabled

MSB OPTION BYTE

LSB OPTION BYTE

Reserved

EXT

CTL

LVD

PRO-

TECT

OSC Res.

Res.

NMI

PULL

TIM

PULL

ACT

OSG

Default

Value

XXX

XXXXX

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