User’s Manual U14826EJ5V0UD
58
CHAPTER 5 EEPROM (DATA MEMORY)
5.1 Memory Space
Besides internal high-speed RAM, the
µ
PD789860, 789861 Subseries have 32
×
8 bits of electrically erasable
PROM (EEPROM) on-chip as data memory.
Unlike normal RAM, EEPROM can maintain its contents even if its power supply is cut. In addition, unlike
EPROM, its contents can be electrically erased without using ultraviolet rays.
5.2 EEPROM Configuration
EEPROM consists of the EEPROM itself and a control section.
The control section consists of EEPROM write control register 10 (EEWC10) which controls EEPROM writing and
a part that detects the termination of writing and generates an interrupt request signal (INTEE0).
Figure 5-1. EEPROM Block Diagram
Data latch
EEPROM
(32
×
8 bits)
Read/write
controller
EEPROM timer
Prescaler
INTEE0
EEPROM write control register 10 (EEWC10)
EWCS102 EWCS101 EWCS100
EWST10
ERE10
EWE10
f
X
/2
5
to f
X
/2
7
(
µ
PD789860 Subseries)
f
CC
/2
5
(
µ
PD789861 Subseries)
Address
latch
Internal bus
8-bit timer 40 output
5.3 EEPROM Control Register
EEPROM is controlled by EEPROM write control register 10 (EEWC10).
EEWC10 is the register that sets the EEPROM count clock selection, and EEPROM write control.
EEWC10 is set with a 1-bit or 8-bit memory manipulation instruction.
RESET input sets this register to 08H.
Figure 5-2 shows the format of EEPROM write control register 10. Tables 5-1 and 5-2 show EEPROM write times.
Содержание PD789860
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