em78f644nso28s ELAN Microelectronics Corp, em78f644nso28s Datasheet - Page 160

• Manufacturer Part Number: em78f644nso28s
• Description: Flash Series 8-bit Microcontroller
• Manufacturer: ELAN Microelectronics Corp

EM78F648/644/642/641/548/544/542/541N
8-Bit Microcontroller
150 •
6.14 DATA EEPROM
The Data EEPROM is readable and writable during normal operation over the whole
Vdd range. The operation for Data EEPROM is base on a single byte. A write
operation makes an erase-then-write cycle to take place on the allocated byte.
The DATA EEPROM memory provides the high erase and writes cycles. A byte write
automatically erases the location and write the new value.
The following are the steps to write to or read data from the EEPROM:
1) Set the EEPC bit to “1” for enable EEPROM power
2) Write the address to EERA8~EERA0 (512 bytes EEPROM address)
3) A. ● Set the EEWE bit to “1”, if the write function is employed
4) A. Wait for the EEDF or WR to be cleared
5) For the next conversion, go to Step 2 as required
6) To save power and make sure the EEPROM are data not used, clear the EEPC.
6.15 Oscillator
6.15.1 Oscillator Modes
The EM78F64x/F54xN can be operated in the four different oscillator modes, such as
Internal RC oscillator mode (IRC), External RC oscillator mode (ERC), High XTAL
oscillator mode (HXT), and Low XTAL oscillator mode (LXT). You can select one of
them by programming OSC2, OCS1, and OSC0 in the CODE Option register. The
following table depicts how these four modes are defined.
The maximum operation frequency of crystal/resonator under different VDD voltages
listed in the table on next page.
XT (XTAL Oscillator mode)
HXT (High XTAL Oscillator mode)
LXT1 (Low XTAL1 Oscillator mode)
LXT2 (Low XTAL2 Oscillator mode)
IRC mode, OSCO (P54) acts as I/O pin
IRC mode, OSCO (P54) acts as RCOUT pin
ERC mode, OSCO (P54) acts as I/O pin
ERC mode, OSCO (P54) acts as RCOUT pin
Oscillator Modes defined by OSC2 ~ OSC0
B. Wait for the EEDF to be cleared
B. Set the RD bit to “1”, then; execute read function
● Write the 8-bit value of the data to be programmed (256 bytes EEPROM data)
● Set the WR bit to “1”, then; execute write function
Mode
(This specification is subject to change without further notice)
Product Specification (V1.0) 05.05.2010
OSC2
0
0
0
0
1
1
1
1
OSC1
0
0
1
1
0
0
1
1
OSC0
0
1
0
1
0
1
0
1