EEPROM-2 Memory

Functional Description

MC68HC908AZ60A — Rev 2.0 Technical Data

MOTOROLA EEPROM-2 Memory 115

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-2 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 Table 7-2.

Note that none of the bit locations are actually programmed more than

once although the byte was programmed eight times.

When this technique is utilized, a program/erase cycle is defined as

multiple program sequences (up to eight) to a unique location followed

by a single erase operation.

Table 7-2. Example Selective Bit Programming Description

Description

Program Data

in Binary

Result

in Binary

Original state of byte (erased) n/a 1111:1111

First event is recorded by programming bit position 0 1111:1110 1111:1110

Second event is recorded by programming bit position 1 1111:1101 1111:1100

Third event is recorded by programming bit position 2 1111:1011 1111:1000

Fourth event is recorded by programming bit position 3 1111:0111 1111:0000

Events five through eight are recorded in a similar fashion

EEPROM-2 Memory

Technical Data MC68HC908AZ60A — Rev 2.0

116 EEPROM-2 Memory MOTOROLA

Program/Erase

Using AUTO Bit

An additional feature available for EEPROM-2 program and erase

operations is the AUTO mode. When enabled, AUTO mode will activate

an internal timer that will automatically terminate the program/erase

cycle and clear the EEPGM bit. Please see EEPROM-2 Programming

on page 116, EEPROM-2 Erasing on page 117 and EEPROM-2

Control Register on page 119 for more information.

EEPROM-2

Programming

The unprogrammed or erase state of an EEPROM bit is a logic 1.

Programming changes the state to a logic 0. Only EEPROM bytes in the

non-protected blocks and the EE2NVR register can be programmed.

Use the following procedure to program a byte of EEPROM:

1. Clear EERAS1 and EERAS0 and set EELAT in the EE2CR.

(A)

NOTE: If using the AUTO mode, also set the AUTO bit during Step 1.

2. Write the desired data to the desired EEPROM address.

(B)

3. Set the EEPGM bit.

(C)

Go to Step 7 if AUTO is set.

4. Wait for time, t

EEPGM

, to program the byte.

5. Clear EEPGM bit.

6. Wait for time, t

EEFPV

, for the programming voltage to fall. Go to

Step 8.

7. Poll the EEPGM bit until it is cleared by the internal timer.

(D)

8. Clear EELAT bits.

(E)

NOTE: A. EERAS1 and EERAS0 must be cleared for programming. Setting the

EELAT bit configures the address and data buses to latch data for

programming the array. Only data with a valid EEPROM-2 address will

be latched. If EELAT is set, other writes to the EE2CR will be allowed

after a valid EEPROM-2 write.

B. If more than one valid EEPROM write occurs, the last address and

data will be latched overriding the previous address and data. Once data

is written to the desired address, do not read EEPROM-2 locations other

than the written location. (Reading an EEPROM location returns the

latched data and causes the read address to be latched).

EEPROM-2 Memory

Functional Description

MC68HC908AZ60A — Rev 2.0 Technical Data

MOTOROLA EEPROM-2 Memory 117

C. The EEPGM bit cannot be set if the EELAT bit is cleared or a non-

valid EEPROM address is latched. This is to ensure proper

programming sequence. Once EEPGM is set, do not read any

EEPROM-2 locations; otherwise, the current program cycle will be

unsuccessful. When EEPGM is set, the on-board programming

sequence will be activated.

D. The delay time for the EEPGM bit to be cleared in AUTO mode is less

than t

EEPGM

. However, on other MCUs, this delay time may be different.

For forward compatibility, software should not make any dependency on

this delay time.

E. Any attempt to clear both EEPGM and EELAT bits with a single

instruction will only clear EEPGM. This is to allow time for removal of

high voltage from the EEPROM-2 array.

EEPROM-2 Erasing The programmed state of an EEPROM bit is logic 0. Erasing changes

the state to a logic 1. Only EEPROM-2 bytes in the non-protected blocks

and the EE2NVR register can be erased.

Use the following procedure to erase a byte, block or the entire

EEPROM-2 array:

1. Configure EERAS1 and EERAS0 for byte, block or bulk erase; set

EELAT in EE2CR.

(A)

NOTE: If using the AUTO mode, also set the AUTO bit in Step 1.

2. Byte erase: write any data to the desired address.

(B)

Block erase: write any data to an address within the desired

block.

(B)

Bulk erase: write any data to an address within the array.

(B)

3. Set the EEPGM bit.

(C)

Go to Step 7 if AUTO is set.

4. Wait for a time: t

EEBYTE

for byte erase; t

EEBLOCK

for block erase;

EEBULK.

for bulk erase.

5. Clear EEPGM bit.

6. Wait for a time, t

EEFPV

, for the erasing voltage to fall. Go to Step 8.

7. Poll the EEPGM bit until it is cleared by the internal timer.

(D)

Part #	8A/S6
Description	Incandescent S Light Lamp
Category	LAMP
Availability	In Stock
Qty	2

8A/S6

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