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CHAPTER 9 KEYPAD PORT

RPC-30 Page 29

Figure 9-1 Keypad connector

INTRODUCTION

16 to 24 position keypads are plugged into keypad port

J5. Keys are arranged in a 4 x 4 to 4 x 6 matrix form at.

A key is recognized when a r ow and a c olumn connect.

CAM BASIC automatically scans and debounces the

keypad every debounce time. D ebounce time is fixed at

80 ms. Keypad presses m ay be return ed either as a

number from 1 to 24 or as an ASCII character. The

ASCII character returned corresponds to those on

Remote Processing's KP-1 keypad. Character

assignments are changed using the SYS(8) function.

Keypads from Remote Processing simply plug into J5.

The keypad cable length should be limited to less than 5

feet.

If the keypad port is not used, it may be used as a

general purpose digital I/O port.

PROGRAMMING EXAMPLE

The following example sets up CAMBASIC to scan a 16

position keypad. The results are echo'ed to the display

and the speaker is sounded when a key is pressed.

20 'Optionally change keypad character 'B'

30 ' to the letter 'M'

40 POKE SYS(8)+7,77

50 CONFIG DISPLAY &50,7,1

60 ON KEYPAD$ GOSUB 500

70 DISPLAY (0,0)"Enter a number"

80 DISPLAY (1,0)

100 'loop for this example

110 GOTO 100

500 A$ = KEYPAD$(0)

510 IF A$ = "C" THEN ..clear_beep

520 IF A$ = "#" THEN ..enter

530 DISPLAY A$;

540 B$ = B$+A$

550 SOUND 600,.2

560 RETURN

600 ..clear_beep

610 B$=""

620 SOUND 600,.2

630 DELAY .4

640 SOUND 600,.2

650 DISPLAY (1,0) " ";

660 RETURN

700 ..enter

710 FL = 1

720 SOUND 800,.5

730 RETURN

Program explanation

Lines 10-80 set up the parameters for the keypad and

display. Line 80 positions the cursor on the next line.

Lines 500 to 730 process the key press. If a "C " or "#"

is pressed, it is an exception and is handled that way.

Otherwise, the character is displayed and stored. A beep

indicates it was saved.

Lines 600 to 660 send a double beep w hen data is

cleared. The buffer (B$) is cleared as is the display.

Lines 700 to 730 process the "enter" key. A longer beep

is sounded and the enter flag, F L, is set to a 1 to indicate

to another part of the program that B$ has complete

data.

The KEYPAD$(0) function returns a single character

string that has been assigned to a particular key. Keypad

positions 17-24 do not have a character assigned to them.

These positions are assigned using the SYS(8) statement.

KEYPAD PORT PI NOUT - J5

The keypad port uses ports B and C from an 82C55.

Lower port C is configured as an input. Upper port C

and port B bits 0 and 1 are outputs. Port B bits are used

only when a 20 or 24 position keypad is installed.

1 2 ... 26 27 28 29 30 31 32 33 34 35 36 37 38

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Remote-processing RPC-30 Manuale Utente Pagina 31

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