4x4 Keypad Controller

This project uses a 4x4 keypad to control 4 remote devices. It will control up to 16 devices but our micro will only allow up to 4 devices.
Keypads are available from many different manufacturers and some are available as a kit. See the range on eBay where the prices are the lowest and postage is FREE.
The items we have chosen to switch ON and OFF are: a LED, globe, piezo buzzer and motor.
Only the first 4 keys are used and they toggle each item ON and OFF.
To make the project more-compact, you can reduce the keys to 4 and only fit the 47k resistors. The keys are 1, 2, 3 and 4 and when you are initially programming the key-values into EEPROM, you simply push 1, 2, 3, 4 and repeat key 4 until the LED flashes.
The keys toggle each item and this allows 4 items to be controlled via two wires.
We are limited to 4 items as we are using a very small 8-pin micro with 5 outputs. One output is already used for the keypad .
This project is another in our series MAKE YOUR OWN CHIPS where we show how to write a program for a microcontroller and produce a project using a single 8-pin micro to take the place of a number of regular IC’s.
You need to refer to our previous project 4x4 Keypad to see how it can be connected to a microcontroller via a single line (plus 0v rail). This project provides an application where a number of keys are needed to provide data for a project – such as an alarm, game or data collection.
Once you have studied the keypad detection program in the previous project, you are ready to add sub-routines to toggle 4 of the outputs.

4x4 keypad connected to a microcontroller and controlling 4 devices

The interface board using surface-mount components

The interface board using through-hole components

The wiring viewed from top

The 4 Devices controlled by the 4x4 Keypad

SOLVING PROGRAMMING PROBLEMS
One of the problems with this type of project is inference from the devices being turned ON and OFF. As more devices are activated, the supply voltage will alter and this will change the timing for the keypad detection.
To keep the voltage on the keypad timing absolutely stable, we have introduced three features.
-The voltage to the chip is regulated by a 5v regulator.
- The voltage on the timing capacitor cannot rise above 4v7 due to the 4v7 zener and
- thirdly, the output of the chip is momentarily turned off during the timing so the load on the port (the 220R resistors to the base of the driver transistors) does not alter the detection-point for the input-line GP5.
Keys 1,2, 3 and 4 have been chosen because they require the longest timing and any fault with the timing will be most-pronounced because these keys have the highest number of timing-loops.
Even though the timing for a key may be 15h loops, it may be actually 14.1 loops and a slight change in the value of the timing capacitor may create a result of 14 loops. To cover this possibility, the program looks at 14 loops, 15 loops and 16 loops. This gives a small degree of variation or tolerance to make the program more reliable.

GOING FURTHER
This project can be extended to provide all sorts of communication-features via "two lines."
You can toggle 2 devices ON and OFF by using separate keys.
You can also provide timing for a device to turn it on for a period of time via one of the keys or a different time by using another key.
You can use two outputs to control a motor in forward-reverse via an "H-Bridge."

INSTRUCTIONS TO SET THE KEY-VALUES
Turn the project OFF.
Push key16 and keep pressed.
Turn ON project.
Release key16.
Push key1 - LED will flash briefly
Push key2 to key16. slowly - LED will flash briefly
after key 16, LED will flash ON-OFF-ON-OFF
Key-values are now in EEPROM.
Turn project OFF
Turn Project ON. Push key1 and LED will turn ON
Push key 2 and globe will turn ON
Push key 3 and piezo buzzer will sound
Push key 4 and motor will turn ON.
Push 1 - 4 and the device will turn OFF.

The files:
4x4KeyPadController.asm
4x4KeyPadController.txt
4x4KeyPadController.hex

;******************************* ;4x4 KeypadController.asm ; ;4x4 keypad connected to 4 devices ; 22-7-2013 ;******************************* list p=12F629 radix dec include "p12f629.inc" errorlevel -302 ; Dont complain about BANK 1 Registers during assembly __CONFIG _MCLRE_OFF & _CP_OFF & _WDT_OFF & _INTRC_OSC_NOCLKOUT ;_MCLRE_OFF - master clear must be off for gp3 to work as input pin ;**************************************************************** ; variables - names and files ;**************************************************************** Cblock 20h temp1 ;used in delays temp2 ;used in delays temp3 ;used in delays temp4 ;used to generate key value temp16 ;16 keys flashes ;LED flashes to indicate key number loops SwFlags endc ;**************************************************************** ;Equates ;**************************************************************** status equ 0x03 rp1 equ 0x06 rp0 equ 0x05 GPIO equ 0x05 status equ 03h option_reg equ 81h ; bits on GPIO pin7 equ 0 ;GP0 LED - flashes to indicate key number pin6 equ 1 ;GP1 Relay pin5 equ 2 ;GP2 Piezo Buzzer pin4 equ 3 ;GP3 not used pin3 equ 4 ;GP4 Motor pin2 equ 5 ;GP5 4x4 Keypad switches ;bits rp0 equ 5 ;bit 5 of the status register ;**************************************************************** ;Beginning of program ;**************************************************************** org 0x00 nop nop nop nop nop SetUp bsf status, rp0 ;Bank 1 movlw b'11001000' ;Set TRIS GP0,1,2,4,5 out GP3 not used movwf TRISIO bcf status, rp0 ;bank 0 movlw 07h ;turn off Comparator ports movwf CMCON ;must be placed in bank 0 clrf GPIO ;Clear GPIO of junk - turn off all devices movlw 4Fh ;start of GPR's movwf fsr call NoKey ;see if a switch is pressed btfss SwFlags,1 ;test bit1 for switch pressed goto SetUp2 ;load 50h to 5Fh from EEPROM call GenKeyvalue ;to see if key16 is pressed before start-up. movlw 0CFh ;Put a value into W and perform SUBWF subwf loops,1 ;Carry flag is CLEAR if W is greater than file value btfsc 03,c ;Test carry flag goto SetUp2 movlw .16 movwf temp16 ;for 16 keys call NoKey ;test bit1 for switch pressed btfsc SwFlags,1 ;detect no key pressed for debounce goto $-2 ; bsf gpio,0 ;Key not pressed - flash LED briefly call _10mS bcf gpio,0 call _10mS call NoKey ;test bit1 for switch pressed btfss SwFlags,1 ;detect key pressed for debounce goto $-2 call GenKeyvalue ;Key pressed - get number of loops incf fsr,f ;fsr starts at file 50h Store 16 key-values movf loops,w ;move number of loops into w movwf indf ;put loops into file 50h to 5Fh decfsz temp16,f goto $-.15 call toEEPROM ;put 16 values into EEPROM bsf gpio,0 call _500mS bcf gpio,0 call _500mS goto $-4 ;keeps flashing - turn off project ;load files 50h to 5Fh with key values from EEPROM SetUp2 bsf status,rp0 ;select bank1 clrf eeadr ;start EEPROM at location 0 bcf status,rp0 ;select bank0 movlw .16 movwf temp16 ;for 16 keys movlw 4Fh ;start of GPR's movwf fsr incf fsr,f ;fsr starts at file 50h bsf status,rp0 bsf EECON1,0 ;starts EEPROM read operation - result in EEDATA movf EEDATA,w ;move read data into w bcf status,rp0 movwf indf ;put EEPROM data into file 50h to 5Fh bsf status,rp0 ;select bank1 incf eeadr,1 bcf status,rp0 ;select bank0 decfsz temp16,f goto $-.10 goto Main ;******************** ;* Delays * ;******************** _uS movlw 7h movwf temp1 decfsz temp1,f goto $-1 retlw 00 _10mS movlw 0Ah movwf temp2 _10 nop decfsz temp1,f goto _10 decfsz temp2,f goto _10 retlw 00 _100mS movlw .100 movwf temp2 _100 nop decfsz temp1,f goto _100 decfsz temp2,f goto _100 retlw 00 _500mS movlw 5 movwf temp3 call _100mS decfsz temp3,1 goto $-2 retlw 00 ;**************************** ;* Sub Routines * ;**************************** Device1 movlw 01h xorwf gpio,1 ;XOR 01 with gpio, lowest line (GP0) retlw 00 ;toggles line gpio,0 Device2 movlw 02h xorwf gpio,1 ;XOR 01 with gpio, lowest line (GP1) retlw 00 ;toggles line gpio,1 Device3 movlw 04h xorwf gpio,1 ;XOR 01 with gpio, lowest line (GP2) retlw 00 ;toggles line gpio,2 Device4 movlw 10h xorwf gpio,1 ;XOR 01 with gpio, lowest line (GP4) retlw 00 ;toggles line gpio,4 ;detect key16 at start-up to generate key-loops for storage in EEPROM ;this sub-routine also detects a pressed-key and ;returns with a value in "loops" GenKeyvalue clrf loops bsf status, rp0 ;Bank 1 bcf TRISIO,5 ;clear bit GPIO,5 as output to charge cap. bcf status, rp0 ;bank 0 bsf gpio,5 ;make pin2 HIGH to charge cap. call _10mS ;charge cap call _10mS ;charge cap call _10mS ;charge cap bsf status, rp0 ;Bank 1 bsf TRISIO,5 ;set TRIS GP0,5 to detect discharged cap bcf status, rp0 ;bank 0 movf gpio,w movwf temp3 clrf gpio ;turn off outputs while detecting call _uS incf loops,1 btfsc gpio,5 goto $-3 movf temp3,w movwf gpio ;re-instate output port retlw 00 ;return with value in loops ;Key_Yes returns SwFlags,7 when file 50h to 5Fh is correct key ;temp4 will already contain file 50h to 5Fh ;GenKeyvalue generates current loops value and compares with ;files 50h to 5Fh Key_Yes bcf SwFlags,7 call GenKeyvalue ;value of key in loops movf loops,w ;put loops into w xorwf temp4,w btfsc 03,z goto bb ;key found incf temp4,f ;try one value higher movf loops,w ;put loops into w again xorwf temp4,w btfsc 03,z goto bb decf temp4,f ;try one value lower decf temp4,f movf loops,w ;put loops into w again xorwf temp4,w btfss 03,z retlw 00 ;key not found bb bsf SwFlags,7 retlw 00 ;NoKey - detect no key pressed NoKey bcf SwFlags,1 bsf status, rp0 ;Bank 1 (see if switch is pressed) bcf TRISIO,5 ;clear bit GPIO,5 as output to charge cap. bcf status, rp0 ;bank 0 bsf gpio,5 ;make pin2 HIGH to charge cap. call _10mS ;charge cap bsf status, rp0 ;Bank 1 bsf TRISIO,5 ;set TRIS GP0,5 to detect discharged cap bcf status, rp0 ;bank 0 call _10mS btfsc gpio,5 retlw 00 ;no switch pressed bsf SwFlags,1 retlw 00 key pressed - bsf SwFlags,1 ;ShowKey shows the key value via LED flashes ShowKey bsf gpio,0 ; call _500mS bcf gpio,0 call _500mS decfsz flashes,1 goto $-5 ; goto Main ;TestKeys is a test routine that flashes the key number TestKeys clrf loops clrf flashes movlw 50h ;start of GPR's movwf fsr aa incf flashes,1 call GenKeyvalue ;value of key in loops movf indf,w ;put contents of 50h into w movwf temp4 xorwf loops,w btfsc 03,z goto ShowKey ;flashes = 1 decf temp4,f ;try one value less movf temp4,w xorwf loops,w btfsc 03,z goto ShowKey ;flashes = 1 incf temp4,f ;try one value higher incf temp4,f movf temp4,w xorwf loops,w btfsc 03,z goto ShowKey incf fsr movlw 16 xorwf flashes,w btfsc 03,z goto aa retlw 00 ;after 16 keys . . . . ;put number of loops in 50h to 5Fh into EEPROM toEEPROM bsf status,rp0 ;select bank1 clrf eeadr ;start EEPROM at location 0 bcf status,rp0 ;select bank0 movlw .16 movwf temp16 ;for 16 keys movlw 4Fh ;start of GPR's movwf fsr incf fsr,f ;fsr starts at file 50h movf indf,w ;retreive data in file 50h to5Fh bsf status,rp0 ;select bank1 movwf eedata ; bcf status,rp0 ;select bank0 call write bsf status,rp0 ;select bank1 incf eeadr,1 bcf status,rp0 ;select bank0 decfsz temp16,f goto $-10 retlw 00 write bsf status,rp0 ;select bank1 bsf eecon1,wren ;enable write movlw 55h ;unlock codes movwf eecon2 movlw 0aah movwf eecon2 bsf eecon1,wr ;write begins bcf status,rp0 ;select bank0 writeA btfss pir1,eeif ;wait for write to complete goto writeA bcf pir1,eeif bsf status,rp0 ;select bank1 bcf eecon1,wren ;disable other writes bcf status,rp0 ;select bank0 retlw 00 ;************************************ ;* Main * ;************************************ Main call NoKey ;test SwFlags,1 for switch pressed btfss SwFlags,1 ;detect key pressed for debounce goto $-2 ;key not pressed movf 50h,w ;is key 1 pressed? movwf temp4 ;set-up temp4 for Key_Yes call Key_Yes btfsc SwFlags,7 call Device1 ;LED movf 51h,w ;is key 2 pressed? movwf temp4 ;set-up temp4 for Key_Yes call Key_Yes btfsc SwFlags,7 call Device2 ;globe movf 52h,w ;is key 3 pressed? movwf temp4 ;set-up temp4 for Key_Yes call Key_Yes btfsc SwFlags,7 call Device3 ;piezo buzzer movf 53h,w ;is key 4 pressed? movwf temp4 ;set-up temp4 for Key_Yes call Key_Yes btfsc SwFlags,7 call Device4 ;motor call NoKey ;test bit1 for switch pressed btfsc SwFlags,1 ;detect key pressed for debounce goto $-2 ;key pressed goto Main ;**************************************************************** ;*EEPROM * ;**************************************************************** org 2100h ;16 locations 00 to 0F END

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22-7-2013