; uncomment following two lines if using 16f627 or 16f628. config uses internal oscillator
	LIST	p=16F628a		;tell assembler what chip we are using
	include "P16F628a.inc"		;include the defaults for the chip
	__config 0x3D18			;sets the configuration settings (oscillator type etc.)

; Filename : keypad.asm
; This is a skelatl program to get you started on reading the keypad and transmitting
; NOTE: there are many details omitted. That's for you to fill in


; Make life easy. Send bits in 1 msec intervals!!


; DECLARE VARIABLES!!!!!!
; We are telling the assembler we want to start allocating symbolic variables starting
;    at machine location 0x20. Please refer to technical documents to see if this is OK!!

cblock 	0x20 			;start of general purpose registers
		count1 			;  count1 is symbolic name for location 0x20
		counta 			;  counta is symbolic name for location 0x21
		countb 			;  countb is symbolic name for location 0x22
		NUMBER
	endc



;un-comment the following two lines if using 16f627 or 16f628
; FORGET THESE 2 LINES AND FUNNY STUFF HAPPENS

	movlw	0x07
	movwf	CMCON			;turn comparators off (make it like a 16F84)
	
; The following is very typical. We must change memory banks to set the TRIS registers

	bsf		STATUS,RP0
	movlw	0x0f
	movwf	TRISB			; portb is input. Remember pushdown (to ground) resisitors on input lines
					; this was erronoeously report as pull-ups. Corrected 2/13/2019
							; membrane keypad
							;  R1  R2  R3  R4  Col1  Col2  Col3  Col4
							;  B0  B1  B2  B3   B4    B5    B6    B7
							;   1   1   1   1    0     0     0     0
	movlw	0x00
	movwf	TRISA			;porta is output. Connect to resistor and IR LED
	bcf     STATUS,RP0		;return to bank 0

;start  main code here
main_loop

read_kbd

	movlw 0x00

	; inelegant code, but it does work!
	; code  1- turn left
	;       2- go straight
	;       3- go right
	;       5- go in reverse
	;       anything else, transmit a zero and stop motors
	
	bsf PORTB, 4			;	lets scan the first column of keys		
	btfsc PORTB, 0			;	has the 1 key been pressed? if yes then send 1
	movlw 0x01			;
	btfsc PORTB, 1			;	has the 4 key been pressed? if yes then
	movlw 0x00			;
	btfsc PORTB, 2			;	has the 7 key been pressed? if yes then
	movlw 0x00			;	copy decimal number 07 into w. but if not then continue on.
	bcf PORTB, 4			;	now we have finished scanning the first column of keys
	
	bsf PORTB, 5			;	lets scan the middle column of keys
	btfsc PORTB, 0			;	has the 2 key been pressed? if yes then
	movlw 0x02			;	copy decimal number 02 into w. but if not then continue on.
	btfsc PORTB, 1			;	has the 5 key been pressed? if yes then
	movlw 0x05			;	copy decimal number 05 into w. but if not then continue on.
	btfsc PORTB, 2			;	has the 8 key been pressed? if yes then
	movlw 0x00			;copy decimal number 00 into w. but if not then continue on.
	bcf PORTB, 5			;	now we have finished scanning the middle column of keys
	
	bsf PORTB, 6			;	lets scan the last column of keys
	btfsc PORTB, 0			;	has the 3 key been pressed? if yes then
	movlw 0x03			;	copy decimal number 03 into w. but if not then continue on.
	btfsc PORTB, 1			;	has the 6 key been pressed? if yes then
	movlw 0x00			;	copy decimal number 06 into w. but if not then continue on.
	btfsc PORTB, 2			;	has the 9 key been pressed? if yes then
	movlw  0x00			;	copy decimal number 09 into w. but if not then continue on.
	bcf PORTB, 6			;	no


;	lazy programmer! didn't even check other keys!!!


	movwf 	NUMBER	
	movf	NUMBER,1
	btfsc	STATUS,Z	; was a number other than 0 entered ? If yes, skip next statement

	goto read_kbd
	
;   Time to transmit. There is a start bit plus three more bits.
;   You might want to read up on the rlf and rrf commands, since you need to
;   shift bits to get to the three low order bits



	send all 4 bits in here


	call	delay_ a_milli_or_2_or_3	; let it resettle!!!!! Don't send stuff so fast!!
	goto	read_kbd	
	
	


	
	end