m3819 Renesas Electronics Corporation., m3819 Datasheet - Page 167

• Manufacturer Part Number: m3819
• Description: Mitsubishi 8-bit Single-chip Microcomputer 740 Family / 38000 Series
• Manufacturer: Renesas Electronics Corporation.

2. APPLICATION
Fig. 2.7.9 Control procedure [Clock count using ZCR interrupt (using a noise filter)]
Control procedure :
Figure 2.7.9 shows a control procedure.
SEI
CLT
CLD
CPUM
ZCRCON
Wait of 2 sampling clocks
IREQ1
NOP
ICON1
1 second counter
(Internal RAM)
CLI
Initialization
ZCR interrupt processing routine (Note 1)
1 second counter
Clock count up (second–year)
1 second counter – 1
(Address:3B
(Address:39
(Address:3C
(Address:3E
Push register to stack
1 second counter = 0?
CLD (Note 3)
CLT (Note 2)
Pop registers
RESET
Set the related registers according to Figure 2.7.8.
At the falling edge of the commercial frequency (50 Hz or 60 Hz), the ZCR interrupt occurs.
The clock is counted up every second in the ZCR interrupt processing routine.
RTI
~ ~
= 0
16
16
16
16
)
), bit6
), bit1
), bit1
50(60)
00000001
0
0
1
50(60)
3819 Group USER’S MANUAL
2
0
2.7 Zero cross detection circuit
All interrupts : Disabled
Main clock division ratio : select the high-speed
Setting of the Zero cross detection control register
Set the INT
ZCR interrupt : Enabled
Input 50 Hz (60 Hz)
Interrupts : Enabled
Note 2 : When using the index X mode flag (T).
Note 3 : When using the decimal mode flag (D).
Push into the register used in the interrupt
processing routine.
Input 50 Hz (60 Hz)
Pop registers which is pushed to stack
Note 1 : The ZCR interrupt occurs with delay of the
Zero cross by a minimum of 1 sampling
clock or a maximum of 2 sampling clocks
because a noise filter is used.
1
/ZCR interrupt request bit to “0”
mode
MITSUBISHI MICROCOMPUTER
3819 Group
153