Motorola Semiconductor Engineering Bulletin EB422 Enhanced
Motorola Semiconductor Engineering Bulletin EB422 Enhanced
Motorola Semiconductor Engineering Bulletin EB422 Enhanced
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Freescale <strong>Semiconductor</strong>, Inc...<br />
<strong>Engineering</strong> <strong>Bulletin</strong><br />
Freescale <strong>Semiconductor</strong>, Inc.<br />
preset values in the EEPROM, placing the device in bootstrap mode<br />
would erase those values even if the EPROM is not blank. If in addition<br />
the device is an OTP, then bootstrap mode is not usable again to<br />
reprogram the contents of the EEPROM.<br />
In summary, this security mode offers a degree of protection for internal<br />
memory contents much greater than standard M68HC11 security mode.<br />
However, users must take great care to ensure that they only enable the<br />
mode when convinced that they have no further need for bootstrap<br />
mode, except, of course, for erasable devices.<br />
The PCbug11 talkers embedded in the 711E20 and 711E32 are full<br />
implementations unlike the PH8 version listed earlier. In this case, as<br />
well as causing a jump to the talker, it is also advisable to initialize the<br />
SWI interrupt vector to point to the null service routine (RTI). This<br />
precaution avoids system problems where the user has an SWI<br />
interrupt. Since the 7E20 and 7E32 talkers vary slightly, the user must<br />
generate two sets of talker and .MAP files. The files are described in:<br />
• Listing 3. PCbug11 MC68HC(7)11E20 Talker Initialization<br />
Code<br />
• Listing 4. PCbug11 MC68HC(7)11E20 Talker Map File<br />
• Listing 5. PCbug11 MC68HC(7)11E32 Talker Initialization<br />
Code<br />
• Listing 6. PCbug11 MC68(7)11E32 Talker Map File<br />
<strong>EB422</strong><br />
8 MOTOROLA<br />
For More Information On This Product,<br />
Go to: www.freescale.com
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