HC05 datasheet(48/232 Pages) MOTOROLA

48 / 232 page

MOTOROLA

3-6

MC68HC05X16

Rev. 1

MEMORY AND REGISTERS

3.5.2

EEPROM read operation

To be able to read from EEPROM, the E1LAT bit has to be at logic zero, as shown in Table 3-1.

While this bit is at logic zero, the E1PGM bit and the E1ERA bit are permanently reset to zero and

the 256 bytes of EEPROM may be read as if it were a normal ROM area. The internal charge pump

generator is automatically switched off since the E1PGM bit is reset.

If a read operation is executed while the E1LAT bit is set (erase or programming sequence), data

resulting from the operation will be $FF.

Note:

When not performing any programming or erase operation, it is recommended that

EEPROM should remain in the read mode (E1LAT = 0)

3.5.3

EEPROM erase operation

To erase the contents of a byte of the EEPROM, the following steps should be taken:

Set the E1LAT bit.

Set the E1ERA bit (1& 2 may be done simultaneously with the same

instruction).

Write address/data to the EEPROM address to be erased.

Set the E1PGM bit.

Wait for a time tERA1.

Reset the E1LAT bit (to logic zero).

While an erase operation is being performed, any access of the EEPROM array will not be

successful.

The erased state of the EEPROM is $FF and the programmed state is $00.

Note:

Data written to the address to be erased is not used, therefore its value is not signiﬁcant.

Table 3-1 EEPROM control bits description

E1ERA

E1LAT

E1PGM

Description

Read condition

Ready to load address/data for program/erase

Byte programming in progress

Ready for byte erase (load address)

Byte erase in progress

HC05 Datasheet(PDF) 48 Page - Motorola, Inc