ST7265X datasheet(159/166 Pages) STMICROELECTRONICS

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ST7265x

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15 DEVICE CONFIGURATION AND ORDERING INFORMATION

Each device is available for production in user pro-

grammable versions (FLASH) as well as in factory

coded versions (ROM). FLASH devices are

shipped to customers with a default content (FFh),

while ROM factory coded parts contain the code

supplied by the customer. This implies that FLASH

devices have to be configured by the customer us-

ing the Option Bytes while the ROM devices are

factory-configured.

15.1 OPTION BYTE

The option byte allows the hardware configuration

of the microcontroller to be selected.

The option byte has no address in the memory

map and can be accessed only in programming

mode (for example using a standard ST7 program-

ming tool). The default content of the FLASH is

fixed to FFh. This means that all the options have

“1” as their default value.

In masked ROM devices, the option byte is fixed in

hardware by the ROM code (see option list)

OPT7 = Reserved. Must be kept at 1.

OPT6 = PE5PU

I/O Port PE5 Pull-up Option

This option bit determines if a pull-up is connected

on Port E5.

0: Pull up present on PE5

1: No pull-up on PE5

When PE5PU=00:

– For input, software can enable or disable the

pull-up by programming PEOR.5 and PED-

DR.5=0.

– For output, the pull-up is enabled when Open

Drain is selected by programming PEOR.5= and

PEDDR.5=1.

Refer to the following table.

OPT5:4 = PSMOD[1:0]

Power Supply Mode

These option bits configure the power supply

mode.

OPT3 = Reserved. Must be kept at 1.

OPT2= WDG SW

Hardware or software watchdog

This option bit selects the watchdog type.

0: Hardware (watchdog always enabled)

1: Software (watchdog to be enabled by software)

OPT1 = USBEN

0: USBEN alternate function disabled. Port F4 is

free for general purpose I/O

1: USBEN alternate function enabled on Port F4

(function controlled by hardware)

OPT0= FMP_R

Flash memory read-out protection

This option indicates if the user flash memory is

protected against read-out piracy. This protection

is based on read and a write protection of the

memory in test modes and IAP. Erasing the option

bytes when the FMP_R option is selected will

cause the whole user memory to be erased first,

and the device can be reprogrammed. Refer to the

ST7 Flash Programming Reference Manual and

section 4.4 on page 22 for more details.

0: Read-out protection enabled

1: Read-out protection disabled

PE5

MOD

WDG

USB

FMP_

Configuration

PE5PU

OPTION

PEOR.5

PEDDR.5

Input floating

Output Open Drain

with Pull-up

Input with pull-up

Output push pull

Input floating

Output Open Drain

Input floating

Output push pull

Mode

OPT5

OPT4

Stand-alone mode forced

Dual Supply (normal) Mode

USB mode forced

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