XC908AS60ACFU Motorola Semiconductor Products, XC908AS60ACFU Datasheet - Page 95

• Manufacturer Part Number: XC908AS60ACFU
• Description: MC68HC908AZ60A, MC68HC908AS60A Hcmos Microcontroller Unit Technical Data
• Manufacturer: Motorola Semiconductor Products

6.5.5 EEPROM-1 Programming and Erasing
MC68HC908AZ60A — Rev 2.0
MOTOROLA
Original state of byte (erased)
First event is recorded by programming bit position 0
Second event is recorded by programming bit position 1
Third event is recorded by programming bit position 2
Fourth event is recorded by programming bit position 3
Events five through eight are recorded in a similar fashion
The unprogrammed or erase state of an EEPROM bit is a logic 1. The
factory default for all bytes within the EEPROM-1 array is $FF.
The programming operation changes an EEPROM bit from logic 1 to
logic 0 (programming cannot change a bit from logic 0 to a logic 1). In a
single programming operation, the minimum EEPROM programming
size is one bit; the maximum is eight bits (one byte).
The erase operation changes an EEPROM bit from logic 0 to logic 1. In
a single erase operation, the minimum EEPROM erase size is one byte;
the maximum is the entire EEPROM-1 array.
The EEPROM can be programmed such that one or multiple bits are
programmed (written to a logic 0) at a time. However, the user may never
program the same bit location more than once before erasing the entire
byte. In other words, the user is not allowed to program a logic 0 to a bit
that is already programmed (bit state is already logic 0).
For some applications it might be advantageous to track more than 10K
events with a single byte of EEPROM by programming one bit at a time.
For that purpose, a special selective bit programming technique is
available. An example of this technique is illustrated in
Note that none of the bit locations are actually programmed more than
once although the byte was programmed eight times.
Table 6-2. Example Selective Bit Programming Description
Description
EEPROM-1 Memory
Program Data
1111:1101
1111:1011
1111:1110
1111:0111
in Binary
n/a
Functional Description
EEPROM-1 Memory
Table
Technical Data
6-2.
1111:1000
1111:0000
1111:1100
in Binary
1111:1111
1111:1110
Result
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