User Manual

EP7309/11/12 User’s Manual - DS508UM4 10-1

1010

Chapter 10

10Keyboard Interface

Introduction

The keyboard interface provides the necessary hardw are for a direct conn ect 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)

See Chapter 5.

Programming Example

;*****************************************************************************

; Purp ose of the code is to read a 1x8 keypad using c olumn 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

;