MC68HC705B16CFN Freescale Semiconductor, MC68HC705B16CFN Datasheet - Page 47
Manufacturer Part Number
IC MCU 2.1MHZ 15K OTP 52-PLCC
Specifications of MC68HC705B16CFN
Number Of I /o
Program Memory Size
15KB (15K x 8)
Program Memory Type
256 x 8
352 x 8
Voltage - Supply (vcc/vdd)
4.5 V ~ 5.5 V
-40°C ~ 85°C
Package / Case
Lead Free Status / RoHS Status
Contains lead / RoHS non-compliant
To be able to read from EEPROM, the E1LAT bit has to be at logic zero, as shown in
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.
To erase the contents of a byte of the EEPROM, the following steps should be taken:
While an erase operation is being performed, any access of the EEPROM array will not be
The erased state of the EEPROM is $FF and the programmed state is $00.
If a second word is to be erased, it is important that the E1LAT bit be reset before restarting the
erasing sequence otherwise any write to a new address will have no effect. This condition provides
a higher degree of security for the stored data.
User programs must be running from the RAM or ROM as the EEPROM will have its address and
data buses latched.
1 Set the E1LAT bit.
1) Set the E1ERA bit (1& 2 may be done simultaneously with the same
2) Write address/data to the EEPROM address to be erased.
3) Set the E1PGM bit.
4) Wait for a time t
5) Reset the E1LAT bit (to logic zero).
When not performing any programming or erase operation, it is recommended that
EEPROM should remain in the read mode (E1LAT = 0)
Data written to the address to be erased is not used, therefore its value is not
EEPROM read operation
EEPROM erase operation
MEMORY AND REGISTERS