CD00001237 Datasheet, PDF (16/105 Pages) STMicroelectronics – 8-bit MCUs with A/D converter

ST6215C ST6225C
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.
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 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.
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
15
Default
Value
X
MSB OPTION BYTE
Reserved
87
LSB OPTION BYTE
EXT
CTL
LVD
PRO-
TECT
OSC
Res.
Res.
NMI
PULL
TIM
PULL
0
WD OSG
ACT EN
XXXXXXXXXXXX
X
XX
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