ST7LITE0 datasheet(116/122 Pages) STMICROELECTRONICS

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ST7LITE0, ST7SUPERLITE

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16 IMPORTANT NOTES

16.1 Execution of BTJX Instruction

Description

Executing a BTJx instruction jumps to a random

address in the following conditions: the jump goes

to a lower address (jump backward) and the test is

performed on a data located at the address

00FFh.

16.2

In-Circuit

Programming

devices

previously

programmed

with

Hardware

Watchdog option

Description

In-Circuit Programming of devices configured with

Hardware Watchdog (WDGSW bit in option byte 1

programmed to 0) requires certain precautions

(see below).

In-Circuit Programming uses ICC mode. In this

mode, the Hardware Watchdog is not automati-

cally deactivated as one might expect. As a conse-

quence, internal resets are generated every 2 ms

by the watchdog, thus preventing programming.

The device factory configuration is Software

Watchdog so this issue is not seen with devices

that are programmed for the first time. For the

same reason, devices programmed by the user

with the Software Watchdog option are not im-

pacted.

The only devices impacted are those that have

previously been programmed with the Hardware

Watchdog option.

Workaround

Devices configured with Hardware Watchdog

must be programmed using a specific program-

ming mode that ignores the option byte settings. In

this mode, an external clock, normally provided by

the programming tool, has to be used. In ST tools,

this mode is called "ICP OPTIONS DISABLED".

Socke ts on ST p ro gramm ing tools (such as

ST7MDT10-EPB) are controlled using "ICP OP-

TIONS DISABLED" mode. Devices can therefore

be reprogrammed by plugging them in the ST Pro-

gramming Board socket, whatever the watchdog

configuration.

When using third-party tools, please refer the

manufacturer’s documentation to check how to ac-

cess specific programming modes. If a tool does

not have a mode that ignores the option byte set-

tings, devices programmed with the Hardware

watchdog option cannot be reprogrammed using

this tool.

16.3

In-Circuit

Debugging

with

Hardware

Watchdog

In Circuit Debugging is impacted in the same way

as In Circuit Programming by the activation of the

hardware watchdog in ICC mode. Please refer to

Section 16.2.

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