Datasheet

Device configuration ST7LITE20F2 ST7LITE25F2 ST7LITE29F2
154/170 DocID8349 Rev 7
15 Device configuration
Each device is available for production in user programmable versions (FLASH) as well as
in factory coded versions (FASTROM).
ST7FLITE2 devices are FLASH versions. ST7PLITE2 devices are Factory Advanced
Service Technique ROM (FASTROM) versions: they are factory programmed FLASH
devices.
ST7FLITE2 devices are shipped to customers with a default program memory content
(FFh), while FASTROM factory coded parts contain the code supplied by the customer. This
implies that FLASH devices have to be configured by the customer using the Option Bytes
while the FASTROM devices are factory configured.
15.1 Option bytes
The two option bytes allow the hardware configuration of the microcontroller to be selected.
The option bytes can be accessed only in programming mode (for example using a standard
ST7 programming tool).
15.1.1 Option byte 0
• OPT7 = Reserved, must always be 1
• OPT6:4 = OSCRANGE[2:0] Oscillator range
When the internal RC oscillator is not selected (Option OSC=1), these option bits select
the range of the resonator oscillator current source or the external clock source.
Note: When the internal RC oscillator is selected, the OSCRANGE option bits must be kept at
their default value in order to select the 256 clock cycle delay (see
Section 7.5: Reset
sequence manager (RSM)).
• OPT3:2 = SEC[1:0] Sector 0 size definition
These option bits indicate the size of sector 0 according to Table 93.
Table 92. Option bytes values
OSCRANGE
210
Typ.
frequency range with
Resonator
LP 1~2MHz 0 0 0
MP 2~4MHz 0 0 1
MS 4~8MHz 0 1 0
HS 8~16MHz 0 1 1
VLP 32.768kHz 1 0 0
External
Clock source:
CLKIN
on OSC1 1 0 1
on PB4 1 1 1
Reserved 1 1 0