EM73P461A
4-BIT MICRO-CONTROLLER FOR LCD PRODUCT
For the pulse width measurement mode, the counter only incresed by the rising edge of internal pulse rate as
external timer/counter input (P8.1/TRGB, P8.3/TRGA ), interrupt request will be generated as soon as
timer/counter count overflow.
P8.1/TRGB(P8.3/TRGA)
Internal pulse
n
n+1
n+2
n+3
n+4
n+5
TimerB(TimerA) value
PROGRAM EXAMPLE: Enable timerA by pulse width measurement mode.
LDIA #1100b;
OUTA P28; Enable timerA with pulse width measurement mode.
HIGH SPEED TIMER/COUNTER
EM73P461A has one 8-bit high speed timer/counter (HTC). It supports three special functions : auto load
timer, melody output and pulse width measurement modes. The HTC is available for the NORMAL and
SLOW operation mode.
The HTC can be set initial value and send counter value to counter registers (P11 and P10), P31 is the
command port for HTC, user can choose different operation mode and different internal clockrate by setting
the port. The timer/counter increase one at the rising edge of internal pulse. The HTC can generate an overflow
interrupt (HTCI) when it overflows. The HTCI cannot be generated when the HTC is in the melody mode
or disabled.
Output data
÷2
FHTC
HTCI interrupt
P4.0/SOUND
SOUND
Overflow
Reload
P31(3,2)
8-bit binary counter
Timer/counter B
mask option
P31(1,0)
Input data
XIN
P11
P10
P4.1/TRGH
Data bus
P31 is the command register of the 8-bit high speed timer/counter.
P31
3
2
1
0
Initial value : 0000
HIPS
HTMS
HIPS
HTMS
Mode selection
Clock rate selection
NORMAL mode
LXIN/20 Hz
SLOW mode
0 0
0 1
1 0
1 1
Stop
0 0
0 1
1 0
LXIN/20 Hz
LXIN/22 Hz
Reserved
Auto load timer mode
Melody mode
Pulse width measurement mode 1 1
LXIN/22 Hz
CLK/24 Hz
CLK/26 Hz
Reserved
P11 and P10 are the counter registers of the 8-bit high speed timer/counter. P10 is the lower nibble register
and P11 is the higher nibble register. (HT is the value of counter registers.)
P11
3
2
1
0
P10
3
2
1
0
Initial value : 0000 0000 (HT)
Higher nibble register
Lower nibble register
* This specification are subject to be changed without notice.
12.27.2001
21
ELAN [ ELAN MICROELECTRONICS CORP ]
