m3819 Renesas Electronics Corporation., m3819 Datasheet - Page 99

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

2. APPLICATION
Fig. 2.2.21 Control procedure [Measurement of frequency]
Control procedure :
Figure 2.2.21 shows a control procedure.
1
SEI
T12M
T34M
ICON1
ICON2
T1
T12M
CLI
T4
IREQ2
Initialization
Timer 1 interrupt processing routine
Processing for a result of judgment
IREQ2 (Address:3D
(A)
(Address:28
(Address:29
(Address:3E
(Address:3F
(Address:20
(Address:28
(Address:23
(Address:3D
214
FSync
<
T4 (Address:23
RESET
(A)
RTI
~ ~
16
16
16
16
16
16
16
16
0
1/8
<
)
)
)
), bit0
)
), bit7
), bit6
), bit1
Out of range
228?
0
16
), bit1?
00000001
00100000
16
)
1
0
64 – 1
0
256 – 1
0
3819 Group USER’S MANUAL
2
2
In range
All interrupts : Disabled
Select the input pulse from the CNTR
pin as the Timer 4 count source.
Timer 1 interrupt : Enabled
Set the division ratio so that the Timer
1 interrupt occurs every 244 s.
Start a timer counting.
Interrupts : Enabled
Set so that the processing Synchro-
nizing signal judgment is performed
every time eight Timer 1 interrupts
occur.
When the count value is 256 or more,
the processing is performed as out of
range.
Read the count value.
Store the count value in the accumu-
lator (A).
Initialize the count value.
Set the Timer 4 interrupt request bit to
“0”.
FSync
Compare the count value read with the
reference value.
Store the comparison result in flag FSync.
1
MITSUBISHI MICROCOMPUTER
3819 Group
1
2.2 Timer
85