EM73PA88A
4-BIT MICRO-CONTROLLER FOR LCD PRODUCT
SYSTEM CLOCK MODE CONTROL
The system clock mode controller can start or stop the high-frequency and low-frequency clock oscillator
and switch between the basic clocks. EM73PA88A has four operation modes (DUAL, SLOW, IDLE and
STOP operation modes).
STOP
operation
mode
High osc : stopped
Low osc : stopped
Command
(P16)
I/O wakeup
Reset
High osc : oscillating
Low osc : oscillating
NORMAL
operation
mode
Command
(P16)
Reset
Command
(P22)
Command
(P22)
Reset release
RESET
operation
Reset
SLOW
operation
mode
High osc : stopped
Low osc : oscillating
Command
(P19)
Reset
I/O or internal timer wakeup
IDLE
(CPU
stops)
High osc : stopped
Low osc : oscillating
Operation Mode
NORMAL
SLOW
Oscillator
System Clock
Available function
One instruction cycle
High, Low frequency High frequency clock LCD, speech, sound gen.
8 / fc
8 / fs
-
-
Low frequency
Low frequency
None
Low frequency clock
CPU stops
LCD
LCD
All disable
IDLE
STOP
CPU stops
DUAL OPERATION MODE
The 4-bit µc is in the DUAL operation mode when the CPU is reseted. This mode is dual clock system
(high-frequency and low-frequency clocks oscillating). It can be changed to SLOW or STOP operation
mode with the command register (P22 or P16).
LCD display, speech synthesizer and sound generator are available for the DUAL operation mode.
SLOW OPERATION MODE
The SLOW operation mode is single clock system (low-frequency clock oscillating). It can be changed to
the DUAL operation mode with the command register (P22), STOP operation mode with P16 and IDEL
operation mode with P19.
LCD display is available for the SLOW operation mode. Speech synthesizer and sound generator are
disabled in this mode.
* This specification are subject to be changed without notice.
10.8.2001
17
ELAN [ ELAN MICROELECTRONICS CORP ]
