PIC16F84A Single Digit Clock coding Problems (Nixie)

[Suraj143]

Hi I’m building nixie’s single digit clock. the original link and the source code you can find here

**broken link removed**

I made and assembled the file and ran the circuit. But I got a problem. The segment “E” is not working all the others working. Why is this?

Table for the numbers also done in a different way. Taken PORTB 2 pins & PORTA all 5pins for the segment. For the table it hasn’t use RETLW. I’m confused with it. I changed more PICS but still having the problem. So I need urgent help from you.

Thanks a lot.

 

[Nigel Goodwin]

You might try reading the datasheet?, RA4 is an open collector output - you need a pullup resistor to make it go high!.

 

[Suraj143]

You might try reading the datasheet?, RA4 is an open collector output - you need a pullup resistor to make it go high!.

Ya thats the problem Nigel.I referred to the data sheet RA4 is open drain type.I missed that pullup resistor.Now its working.

thankx .

 

[Nigel Goodwin]

Ya thats the problem Nigel.I referred to the data sheet RA4 is open drain type.I missed that pullup resistor.Now its working.

It's a VERY, VERY, VERY common mistake! - I still do it occasionally even now!.

 

[pasanlaksiri]

Thanks friend. This info is very usefull for me also. Coz i also have same problem

 

[Nigel Goodwin]

Thanks friend. This info is very usefull for me also. Coz i also have same problem

No need to thank me, you will find the same information posted all over this forum by MANY different people - like I said, it's a VERY common mistake.

It's funny, sometimes you really curse it for being different, then another day you wish all the outputs were like that! - you just can't win!

 

[mrpicing]

hi every body! we all humen makes same mistakes many times.
But i try to start with some tips. checking of powersupply, reset pin,oscilator, low voltage programming pin, and always RA4.
and Nigel Goodwin is every where in the pic forums with his excellent experties.

Have a nice day!

 

[grantecnico]

Good morning to all the forums and good year 2009
by the new user forum "grantecnico" by Italy.

I ask you humbly apologize for my English by google transferred, but does not speak English.

I try to help this project can not operate.

I use a Seven-segment display common anode common.
but at the time of the test segments are turned on or not randomly turn on their own.
I have absolutely committed errors of connection and even programming errors.
in addition are not expert in assembler.

I just programmed the pic 16f84a with the file for 24 hours removed from the site for the project numitron compatible to 100 to 100 with this clock.

not satisfied, I repeated the test with the file 12 hours

perhaps the hex file, is incorrect. I doubt this, if someone kindly I can move the file right, thank you in advance and the renewal wishes for the new year

 

[bmoke]

Xorlw 1^2

Uncle. I give up. I have been very unsuccessful at trying to find or figure out how this instruction works. I glanced at the coding for the Nixie clock and I saw the expression, or instruction, XORLW 1^2. I Googled here and there and could only find one page that described it as a bit test of the W register, that could also restore the original value of W. It allowed for comparisons. In the Nixie example (**broken link removed**), the expression and three similar that follow, test for only 4 values, 1 to 4. I have played and played with the bit arithmetic and cannot figure out how the heck these tests work. It looks like it could be of value, although I have looked at a lot of code and do not see it used often.

Here is the section that gives me trouble:

MOVF    FRAME,W
	XORLW   1               
	BTFSC   STATUS,Z
	 GOTO    DHOUR10        ; display 10s of hours when frame is 1
	XORLW   1^2
	BTFSC   STATUS,Z
	 GOTO    DHOUR          ; display hour when frame is 2
	XORLW   2^3
	BTFSC   STATUS,Z
	 GOTO    DMIN10         ; display 10s of mins when frame is 3
	XORLW   3^4
	BTFSC   STATUS,Z
	 GOTO    DMIN           ; display mins when frame is 4 
	MOVLW   00              ; otherwise blank display

In one web example that I could find at PIC Microcontoller Bit Math Method Testing bits in W, they had values on either side of the "^" XOR symbol flipped, from what was used in the Nixie example. I cannot figure out if that is significant, or not.

I hope someone could walk me through this one, or point to some other explanation of value.

Bill M