The circuit is very similar to the 2-Digit Up/down Counter on P1 and is constructed on proto-type PC board for easy modification.
When the project is first turned on, the display shows "0." When the gear-change is pressed in the up direction, the counter increments. It does not go past "6." If the bike is in 6th gear and the gear-change is pressed up, the counter does not increment.
In addition, the counter only decrements to "1."
If the counter gets out of synchronisation, the RESET button is repeatedly pressed and this makes the display show: 0-1-2-3-4-5-6.  That's why it is called "RESET / CYCLE 0-6."

For 12v use, a 5v regulator such as 78L05 has been included. The kit comes with a pre-programmed PIC12F629 and all components for assembly on a proto-type PC board using 14 yellow LEDs. The display is 30mm high and can be separated from the board containing the PIC chip for easy placement on the dashboard.


The program is very simple and has just three sub-routines, Up, Down and Reset.
In Main, the program detects one of three switches, using two inputs. The Down button takes both inputs LOW while the Up and Reset buttons take only one line LOW. It takes only 6 lines of code to produce an outcome. Firstly the Reset (or Cycle) button is polled. If GP0 is LOW, we need to check if the other input (GP3) is LOW before we can make a decision. If GP3 is not LOW, Reset has been pushed.
If GP3 is LOW, Down has been pressed.
Now we go back to the first line of code where we polled the Reset button. If GP0 is not LOW but GP3 is LOW, the Up button has been pressed. Here are the 6 lines of code, starting at  btfsc GPIO,0

	
	;Car Gears Up/Down Counter   12F629.asm
	

Main	bsf	status, rp0 	;Bank 1			
       	movlw	b'11111101'	;Set TRIS  to detect switches  
	movwf	TRISIO	   	; GP0&GP3=in
	bcf	status, rp0	;bank 0 
	btfsc	GPIO,0	
	goto	$+4 		;goto XX as reset not pushed
	btfss	GPIO,3		;reset or down pushed
	goto	Down		;down pushed	
	goto	Reset		;reset pushed
	btfss	GPIO,3		;XX
	goto	Up		;up pushed	
	clrf	Sw_Flag		;nothing pushed		
M1	movf	count,w
	call	table			
	goto	Main
	

When the project is turned on it starts with "0" on the display.
The Down button does not function when "0" is displayed.
The Up button only increments to 6. The down button only decrements to "1."
The Cycle button increments to 6 then displays "0,1,2,3,4,5,6." These "stops" or "limits" are created in the  Up  Down and Reset sub-routines by comparing the "count" file with a value such as 6, 0 or 1.

The Display uses 14 yellow LEDs and have a characteristic voltage-drop of 1.9v  When 4 LEDs are placed across the supply, they require 7.6v and thus they will not illuminate on a 5v rail.
But if one of the outputs of the PIC chip is connected to the mid point of the LEDs, the two lower LEDs will illuminate when the output is HIGH and the two top LEDs will illuminate when the output is LOW. This is how we activate two segments from a single output line.
By rapidly changing the output LOW, HIGH, LOW etc, we can illuminate two segments at the same time.

 
 

Here are the files:
Car.asm
Car.txt (asm)
Car.hex
Car-h.txt (.hex)

Mr R Cermak wanted a counter for his bike with the following features:
The counter comes on with "0"
Down is pressed for "1" then Up for 2,3,4,5,6.
If Up is pressed at the beginning, display shows 2.

The following files are for his features and uses Circuit 1:

Bike Gears -2.asm
Bike Gears -2 .hex