MC68HC711xxxx Motorola, MC68HC711xxxx Datasheet - Page 211

• Manufacturer Part Number: MC68HC711xxxx
• Description: Microcontrollers
• Manufacturer: Motorola

AN1060 — Rev. 1.0
MOTOROLA
Bootstrap mode is useful both at the component level and after the MCU
has been embedded into a finished user system.
At the component level, Motorola uses bootstrap mode to control a
monitored burn-in program for the on-chip electrically erasable
programmable read-only memory (EEPROM). Units to be tested are
loaded into special circuit boards that each hold many MCUS. These
boards are then placed in burn-in ovens. Driver boards outside the
ovens download an EEPROM exercise and diagnostic program to all
MCUs in parallel. The MCUs under test independently exercise their
internal EEPROM and monitor programming and erase operations. This
technique could be utilized by an end user to load program information
into the EPROM or EEPROM of an M68HC11 before it is installed into
an end product. As in the burn-in setup, many M68HC11s can be gang
programmed in parallel. This technique can also be used to program the
EPROM of finished products after final assembly.
Motorola also uses bootstrap mode for programming target devices on
the M68HC11 evaluation modules (EVM). Because bootstrap mode is a
privileged mode like special test, the EEPROM-based configuration
register (CONFIG) can be programmed using bootstrap mode on the
EVM.
The greatest benefits from bootstrap mode are realized by designing the
finished system so that bootstrap mode can be used after final
assembly. The finished system need not be a single-chip mode
application for the bootstrap mode to be useful because the expansion
bus can be enabled after resetting the MCU in bootstrap mode. Allowing
this capability requires almost no hardware or design cost and the
addition of this capability is invisible in the end product until it is needed.
The ability to control the embedded processor through downloaded
programs is achieved without the disassembly and chip-swapping
usually associated with such control. This mode provides an easy way
to load non-volatile memories such as EEPROM with calibration tables
or to program the application firmware into a one-time programmable
(OTP) MCU after final assembly.
Another powerful use of bootstrap mode in a finished assembly is for
final test. Short programs can be downloaded to check parts of the
Application Note
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