m3819 Renesas Electronics Corporation., m3819 Datasheet - Page 166

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

2. APPLICATION
Fig. 2.7.8 Setting of related registers [Clock count using ZCR interrupt (using a noise filter)]
152
2.7.4 Zero cross detection circuit application example 2
Clock count using ZCR interrupt (using a noise filter)
Figure 2.7.8 shows a setting of related registers.
Note :
Outline : The clock is counted up every second by using the ZCR interrupts.
Specifications : • f(X
IREQ1
ICON1
IREQ1
ZCRCON
INTEDGE
When changing the values of bit 0 of the zero cross detection control register and bit 1 of the
However, the value of bit 1 of the interrupt request register 1 is changed with a maximum delay
of 2 sampling clocks by using a noise filter. Thus, after changing, set this bit to “0” after a wait
of 2 sampling clocks.
interrupt edge selection register, make sure the following contents.
1. During changeing, set bit 1 of the interrupt control register 1 (disable ZCR interrupt) to “0”.
2. After changeing, set bit 1 of the interrupt request register 1 (no ZCR interrupt request) to “0”.
Interrupt request register 1 (Address:3C
Interrupt control register 1 (Address:3E
Interrupt request register 1 (Address:3C
Zero cross detection control register (Address:39
Interrupt edge selection register (Address:3A
• The noise filter (sampling clock : f(X
• The commercial frequency (50 Hz or 60 Hz) is input.
• The clock is counted up by using the ZCR interrupts.
(Pulse less than 64 s is eliminated as a noise.)
IN
)=4 MHz
0
1 1
1
0
0
1
3819 Group USER’S MANUAL
ZCR active edge : Falling edge active (Note)
Selection of one-sided edge detection
Passing through the zero cross detection circuit (Note)
Noise filter sampling clock : f(X
Set the INT
INT
ZCR interrupt request
2.7 Zero cross detection circuit
1
/ZCR interrupt : Enabled
16
16
16
)
)
)
IN
1
)/256) is used.
/ZCR interrupt request bit to “0”
16
)
16
)
IN
)/256
MITSUBISHI MICROCOMPUTER
3819 Group