Remote Processing RPC-52 - Manual (Page 27)

CHAPTER 9 KEYPAD PORT
Page 25
Figure 9-1 Keypad connector
INTRODUCTION
16, 20, or 24 position keypads are plugged into keypad
port J5. Keys are arra nged in a m atrix for mat. A key is
recogn ized whe n a row and a colum n connect.
RPBASIC-52 scans and debounces the keypad every
d e bo u nc e ti m e a s de f in e d b y C ON F I G KE Y P A D .
Keypad presses are returned as a num ber from 1 to 24
using the KEYPAD function.
Keypads from Rem ote Processing simply plug into J5.
The keypad cable length should be limited to less than 5
feet.
PROGRAMMING EXAMPLE
The following example sets up RPBASIC-52 to scan a 16
position keypa d. T he results a re echo ' ed when a key is
pressed. C ONF IG KEYP AD is entered in the comma nd
mode. It need be entered only once. Press the 'D ' key
to enter.
CONFIG KEYPAD 5
10 STRING 200,20
20 $(0) = "123A456B789C*0#D"
30 P = 1
40 PF = 0
50 PRINT "Enter a number from the keypad",
REM Rest of program continues
REM Scan keypad and update display
200 GOSUB 500
210 IF PF = 0 THEN 200
220 PRINT
230 PRINT "Entered string is: ",$(2)
240 PF = 0
250 GOTO 50
500 A = KEYPAD(0)
510 IF A = 0 THEN 500
520 IF A = 12 THEN 600 : REM Process clear
530 IF A = 16 then 700 : REM process enter
540 A=ASC($(0),A)
550 PRINT CHR(A),
560 ASC($(2),P) = A
570 P = P + 1
580 ASC($(2),P) = 13
590 RETURN
600 REM Clear input string
610 $(2) = ""
620 P = 1
630 RETURN
700 REM Enter processing
710 P = 1
720 PF = 1
730 RETURN
Program explanation
Line 20 defines the keypad legend. Letters may be
redefined as necessary.
Line 30 sets the position counter used to insert characters
into the string.
Line 200 w aits for a ke y press. The enter ed string is
printed.
Line 500 checks the keypad. If a character is available,
it processe s it.
Lines 540-590 update the input string and position. A
< CR> is inserted to mark the end of string.
KEYPAD PORT PIN OUT - J5
The keypad port uses ports B and C from an 82C55.
Lowe r por t C is configu red as an input. Upper port C
and port B bits 0 and 1 are ou tputs.
The table b elow lists J5' s pin out, 82C55 p ort and bit,
and its intended function.
Pin 82C55 Function
Port/ bit
1 C / 0 Row 1
2 C / 6 Column 3
3 C / 5 Column 2
4 C / 1 Row 2
5 C / 2 Row 3
6 C / 4 Column 1
7 C / 7 Column 4
8 C / 3 Row 4
9 B/0 Column 5
10 B/1 Column 6
COMMANDS
The following is a list of RPBASIC-52 commands for
the keypad.
Comm and Function
CONFIG
KEYPAD Sets keypad parameters
KEYPA D(n) Returns last key from keypad
port