MC68HC05X16 Datasheet, PDF (191/232 Pages) Freescale Semiconductor, Inc – High-density complementary metal oxide semiconductor HCMOS) microcontroller unit

Freescale Semiconductor, Inc.
B.5
EPROM
The MC68HC705X32 memory map is given in Figure B-2. The device has a total of 31248 bytes
of EPROM. 16 bytes are used for the reset and interrupt vectors from address $7FF0 to $7FFF.
The main EPROM block of 31232 bytes is located from $0400 to $7DFF. One byte of EPROM is
used as an option register and is located at address $7FDE.
The EPROM can be completely tested before assembly with sequences of both program and
erase. It is finally erased before being typically assembled in a package with no erase window.
Therefore, only programming is possible and the EPROM operates as a PROM.
The EPROM array is supplied by the VPP6 pin in both read and program modes. Typically the
user’s software would be loaded into a programming board where V_PP6 is controlled by one of the
bootstrap loader routines. It would then be placed in an application where no programming occurs.
In this case the VPP6 pin should be hardwired to V_DD.
Warning: A minimum V_PP6R voltage must be applied to the VPP6 pin at all times, including
power-on. Failure to do so could result in permanent damage to the device. Unless
otherwise stated, EPROM programming is guaranteed at ambient temperature (25°C)
only.
B.5.1 EPROM read operation
The execution of a program in the EPROM address range or a load from the EPROM are both read
operations. The E6LAT bit in the EPROM/EEPROM control register should be cleared to ‘0’ which
automatically resets the E6PGM bit. In this way the EPROM is read like a normal ROM. Reading
the EPROM with the E6LAT bit set will give data that does not correspond to the actual memory
content. As interrupt vectors are in EPROM, they will not be loaded when E6LAT is set. Similarly,
the bootstrap ROM routines cannot be executed when E6LAT is set. In read mode, the VPP6 pin
must be at the V_PP6R level. When entering the STOP mode, the EPROM is automatically set to the
read mode.
Note: An erased byte reads as $00.
MC68HC05X16
MC68HC705X32
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B-7