Difference between revisions of "Programming:Keyboard scanning"

From CPCWiki - THE Amstrad CPC encyclopedia!
Jump to: navigation, search
(Initial page)
 
(added routine for complete keyboard scanning)
Line 1: Line 1:
This is a routine which scans the keyboard directly. It is approximately 8% faster then the firmware routine and doesn't enable interrupts.
 
 
'''Input:''' A = ''layer (&40 - &49)
 
 
'''Output:''' A = ''hardware keyboard value''
 
 
'''Destroyed:''' BC
 
 
 
 
== Hardware scancode table ==
 
== Hardware scancode table ==
 
{|{{Prettytable|width: 700px; font-size: 2em;}}
 
{|{{Prettytable|width: 700px; font-size: 2em;}}
Line 33: Line 24:
 
|}
 
|}
  
== Scanning routine ==
+
== One line scanning routine ==
 +
 
 +
This is a routine which scans one line of the keyboard directly. It is approximately 8% faster then the firmware routine and doesn't enable interrupts.
 +
 
 +
'''Input:''' A = ''layer (&40 - &49)
 +
 
 +
'''Output:''' A = ''hardware keyboard value''
 +
 
 +
'''Destroyed:''' BC
 +
 
 
<pre>
 
<pre>
 
ld a, layer ;use the value from the table above
 
ld a, layer ;use the value from the table above
Line 50: Line 50:
 
ld bc, &F600
 
ld bc, &F600
 
out (c), c
 
out (c), c
 +
</pre>
 +
 +
Now check for the value from the table
 +
e.g. with''' 'cp <value>' '''
 +
and a condition
 +
e.g.''' 'jp <condition>, xxxx' '''or''' 'call <condition>, xxxx' '''
 +
 +
Please note:
 +
* Bit = 0: Key is pressed
 +
* Bit = 1: Key is not pressed
 +
 +
 +
== Complete keyboard scanning routine ==
 +
 +
This routine scans the complete keyboard and writes all key status bits in a map.
 +
 +
<pre>
 +
keymap  ds 10  ;map with 10*8 = 80 key status bits (bit=0 key is pressed)
  
;now check for the value from the table
+
keyscan di              ;1 ##%%## C P C  VERSION ##%%##
;e.g. with 'cp <value>'
+
        ld hl,keymap    ;3
;and a condition
+
        ld bc,#f782    ;3
;e.g. 'jp <condition>, xxxx' or 'call <condition>, xxxx'
+
        out (c),c      ;4
 +
        ld bc,#f40e    ;3
 +
        ld e,b          ;1
 +
        out (c),c      ;4
 +
        ld bc,#f6c0    ;3
 +
        ld d,b          ;1
 +
        out (c),c      ;4
 +
        ld c,0          ;2
 +
        out (c),c      ;4
 +
        ld bc,#f792    ;3
 +
        out (c),c      ;4
 +
        ld a,#40        ;2
 +
        ld c,#4a        ;2 44
 +
loop    ld b,d          ;1
 +
        out (c),a      ;4 select line
 +
        ld b,e         ;1
 +
        ini            ;5 read bits and write into KEYMAP
 +
        inc a          ;1
 +
        cp c            ;1
 +
        jr c,loop      ;2/3 9*16+1*15=159
 +
        ld bc,#f782    ;3
 +
        out (c),c      ;4
 +
        ei              ;1 8 =211 microseconds
 +
        ret
 
</pre>
 
</pre>

Revision as of 07:57, 27 August 2006

Hardware scancode table

Value:
Layer
&7F &BF &DF &EF &F7 &FB &FD &FE
&40 (ZB) ENTER F3 F6 F9 CURDOWN CURRIGHT CURUP
&41 F0 F2 F1 F5 F8 F7 COPY CURLEFT
&42 CONTROL \ SHIFT F4 ] RETURN [ CLR
&43 . /  :  ; P @ - ^
&44 , M K L I O 9 0
&45 SPACE N J H Y U 7 8
&46 V B F G T R 5 6
&47 X C D S W E 3 4
&48 Z CAPSLOCK A TAB Q ESC 2 1
&49 DEL - - - - - - -

One line scanning routine

This is a routine which scans one line of the keyboard directly. It is approximately 8% faster then the firmware routine and doesn't enable interrupts.

Input: A = layer (&40 - &49)

Output: A = hardware keyboard value

Destroyed: BC

ld a, layer	;use the value from the table above
ld bc, &F6C0
out (c), c
ld bc, &F40E
out (c), c
ld bc, &F792
out (c), c
ld b, &F6
out (c), c
ld b, &F4
in a, (c)
ld bc, &F782
out (c), c
ld bc, &F600
out (c), c

Now check for the value from the table e.g. with 'cp <value>' and a condition e.g. 'jp <condition>, xxxx' or 'call <condition>, xxxx'

Please note:

  • Bit = 0: Key is pressed
  • Bit = 1: Key is not pressed


Complete keyboard scanning routine

This routine scans the complete keyboard and writes all key status bits in a map.

keymap  ds 10  ;map with 10*8 = 80 key status bits (bit=0 key is pressed)

keyscan di              ;1 ##%%## C P C   VERSION ##%%##
        ld hl,keymap    ;3
        ld bc,#f782     ;3
        out (c),c       ;4
        ld bc,#f40e     ;3
        ld e,b          ;1
        out (c),c       ;4
        ld bc,#f6c0     ;3
        ld d,b          ;1
        out (c),c       ;4
        ld c,0          ;2
        out (c),c       ;4
        ld bc,#f792     ;3
        out (c),c       ;4
        ld a,#40        ;2
        ld c,#4a        ;2 44
loop    ld b,d          ;1
        out (c),a       ;4 select line
        ld b,e          ;1
        ini             ;5 read bits and write into KEYMAP
        inc a           ;1
        cp c            ;1
        jr c,loop       ;2/3 9*16+1*15=159
        ld bc,#f782     ;3
        out (c),c       ;4
        ei              ;1 8 =211 microseconds
        ret