EM78815
8-Bit Microcontroller
Bit 6 Unused
The following figure shows the relationship between Keyscan, and Key strobe. Fig.24
is a Keyscan flow by interrupt trigger.
Relationship Between Port 8, Port 9, Keyscan, Keystrobe
Keyscan
Control
Keyscan Pulse
0
Port 8, Port 9
MUX
Key strobe
Signal
1
Key strobe
Fig. 23 Keyscan, Key strobe and Segments
Set Port 7(3:0) input
Port 7 pull high
Enable Keyscan signal
Set INT0~INT3 interrupt
ENI
N
Interrupt occur?
Y
Enable main clock (Normal mode)
Program delay
Execution
Analysis external interrupt (column key )
Set strobe function
Key function
Enable Key strobe
Program delay
Read strobe data (row key)
Get the Key location
Fig. 24 Key Scan Flow By Interrupt Trigger
Product Specification (V2.4) 08.01.2004
(This specification is subject to change without further notice)
45
ELAN [ ELAN MICROELECTRONICS CORP ]
