EM73PA88A
4-BIT MICRO-CONTROLLER FOR LCD PRODUCT
LDL #5h;
LDH #3h;
STDMI #0Ah; RAM[35] ← Ah
(3) L register is used as a pointer to indicate the bit of I/O port for instructions : SELP, CLPL, TFPL,
(When LR = 0 indicate P4.0)
PROGRAM EXAMPLE: To set bit 0 of Port4 to "1"
LDL #00h;
SEPL ; P4.0 ← 1
STACK POINTER (SP)
Stack pointer is a 4-bit register that stores the present stack level number.
Before using stack, user must set the SP value first, CPU will not initiate the SP value after reset condition.
When a new subroutine is received, the SP is decreased by one automatically, likewise, if returning from
a subroutine, the SP is increased by one.
The data transfer between ACC and SP is done with instructions "LDASP" and "STASP".
DATA POINTER (DP)
Data pointer is a 12-bit register that stores the ROM address can indicating the ROM code data
specified by user (refer to data ROM).
CLOCK AND TIMING GENERATOR
The clock generator is supported by a dual clock system. The high-frequency oscillator is internal oscillator,
the working frequency is 4.6 MHz. The low-frequency oscillator may be sourced from crystal or RC osc,
the working frequency is 32 KHz.
CLOCK GENERATOR STRUCTURE
There are two clock generator for system clock control unit, P14 is the status register that hold the CPU
status. P16, P19 and P22 are the command register for system clock mode control.
CLK
fc
High-frequency
generator
P14
P16
System clock
mode control
LXIN
fs
P19
P22
Low-frequency
generator
LXOUT
System control
R
LXIN
VDD
LXIN
LXOUT
LXOUT
open
Crystal connection
RC oscillator connection
R=1MΩ
* This specification are subject to be changed without notice.
10.8.2001
16
ELAN [ ELAN MICROELECTRONICS CORP ]
