m3819 Renesas Electronics Corporation., m3819 Datasheet - Page 135

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

2. APPLICATION
Fig. 2.5.18 Control procedure of Segment key-scan
Segment key-scan (FLD blanking interrupt) :
N
FLD blanking interrupt processing routine
FLDM2
P1
P0
P3
Push register to stack etc.
Set Key-scan completion flag
Initialize data table pointer for Key-scan
Renew data table pointer for Key-scan
P3
P0
FLDM2
Transfer the contents of P2
(Address:04
Set data table for Key-scan
to P3 (Address:06
Complete Key-scan?( Note)
(Address:37
(Address:02
(Address:00
(Address:06
(Address:06
(Address:00
(Address:37
Wait for Key-scan
16
RTI
~ ~
16
16
16
16
) to Work RAM
), bit0
), bit0-bit3
)
)
Y
16
16
16
)
)
), bit0
16
)
3819 Group USER’S MANUAL
00
00
1
0
0000
00
00
16
16
16
16
2
Segment key-scan
Switch the FLD automatic display pin to the
ordinary port.
Wait until the “H” level output of port P3
stabilized.
Read keys.
(Set the Port P2 direction register (P2D)
(Address:05
initialization.)
Renew the data table reference pointer for the
next Key-scan.
Set the flag for checking if the Key-scan has
been completed.
Output “L” level from all Key-scan ports.
Switch the FLD automatic display pin to the
automatic display mode.
Note : When the Key-scan is not completed
i = 0 to 7
within the Tscan setting time, it is
divided and performed
16
)
to
2.5 FLD controller
input
MITSUBISHI MICROCOMPUTER
mode
3819 Group
in
i
the
is
121