Cirrus Logic EP73xx - Manual (Page 101)

EP7309/11/12 User’s Manual - DS508UM4 10-1
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Copyright Cirrus Logic, Inc. 2003
1010
10
Chapter 10
10 Keyboard Interface
Introduction
The keyboard interface provides the necessary hardware for a direct connect to an 8x8
or 64-key entry keyboard. Scanning for a keypress involves column and GPIO pins
which assert and read column by column. If enabled, there is an internal interrupt
that be generated from a keypress.
Features
• Maximum direct interface of an 8x8 array
• Dedicated column drives and GPIOs for detection
• Keyboard interrupt (if enabled)
Register List
See Chapter 5 .
Programming Example
;*****************************************************************************
; Purpose of the code is to read a 1x8 keypad using column 1 drive and read
; From GPIO Port A pins. Keypress should also generate an interrupt
;*****************************************************************************
KBD6_WEN EQU 0x8 ; All eight Port A ORed to create interrupt, Keypress
; will also Wakeup processor from Standby state
PortA_DR EQU 0x80000000
SYSCON1 EQU 0x80001000
;
ldr r0, = SYSCON1
ldr r2, = PortA_DR
mov r1, #KBD6_WEN ; Interrupt enabled
str r1,[r0,#0x100] ; SYSCON1 bits set for
;
;......... from the interrupt routine....................
;
mov r3, #0x9
str r3, [r2,#0x100] ; assert column1 drive for keypress read
ldr r1, [r2,#0x0] ; read Port A for Keypress value.
mov r4, #0xff
str r4, [r0, #700] ; clear keyboard interrupt
;