ST7232A datasheet(145/157 Pages) STMICROELECTRONICS

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ST7232A

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14 ST7232A 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). ST7232A devices are

ROM versions. ST72P32A devices are Factory

Advanced Service Technique ROM (FASTROM)

versions: they are factory-programmed HDFlash

devices. FLASH devices are shipped to customers

with a default content (FFh), while ROM factory

coded parts contain the code supplied by the cus-

tomer. This implies that FLASH devices have to be

configured by the customer using the Option Bytes

while the ROM devices are factory-configured.

14.1 FLASH OPTION BYTES

The option bytes allows the hardware configura-

tion of the microcontroller to be selected. They

have no address in the memory map and can be

accessed only in programming mode (for example

using a standard ST7 programming tool). The de-

fault content of the FLASH is fixed to FFh. To pro-

gram directly the FLASH devices using ICP,

FLASH devices are shipped to customers with an

internal clock source. In masked ROM devices,

the option bytes are fixed in hardware by the ROM

code (see option list).

OPTION BYTE 0

OPT7= WDG HALT Watchdog reset on HALT

This option bit determines if a RESET is generated

when entering HALT mode while the Watchdog is

active.

0: No Reset generation when entering Halt mode

1: Reset generation when entering Halt mode

OPT6= 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)

OPT5:1 = Reserved, must be kept at default value.

OPT0= FMP_R Flash memory read-out protection

Read-out protection, when selected, provides a

protection against Program Memory content ex-

traction and against write access to Flash memo-

ry.

Erasing the option bytes when the FMP_R option

is selected causes the whole user memory to be

erased first, and the device can be reprogrammed.

Refer to Section 7.3.1 on page 37 and the ST7

Flash Programming Reference Manual for more

details.

0: Read-out protection enabled

1: Read-out protection disabled

STATIC OPTION BYTE 0

STATIC OPTION BYTE 1

WDG

OSCTYPE

OSCRANGE

Default

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