Remote Technologies RPC-320 manual Keypad Port, Program explanation

KEYPAD PORT

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 50 ms. Keypad pr esses are retur ned as a num ber fr om 1 to 24 using the KE YPA D function . Ke ypad scann ing is always active and cannot be turned off. Up to 8 key presses are buffered.

Keypad presses are multi- tasked using ON KEYPAD . When a key is pressed, the program br anches to the subroutine.

Keypads from Rem ote Processing simply plug into J5. The keypad cable length should be limited to less than 5 feet.

Figure 9-1 Keypad connector

PROGRAMMING EXAMPLE

The following example sets up RPBASIC to scan a 16 position keypa d. T he results a re echo ' ed when a key is pressed. Press the 'D' key to enter .

SECTION 9

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

540A=ASC($(0),A)

550PRINT CHR(A),

560ASC($(2),P) = A

570P = P + 1

580ASC($(2),P) = 13

590RETURN

600REM Clear input string

610$(2) = ""

620P = 1

630RETURN

700REM Enter processing

710P = 1

720PF = 1

730RETURN

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.

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