Binary Clock from Highschool, Lost code PIC18f2525

ericgibbs

Joined Jan 29, 2010
18,766
hi,
Reasonable reading by 'ak'.?
I have attempted to tidy the LED matrix.
The transistors ak-a as FET's [ there's a pun somewhere in that phrase].
The switches need work.
E
Binary-clock3.jpg
 

jpanhalt

Joined Jan 18, 2008
11,087
Please double check the supply and ground circuits. There is still the problem of shorting.

Second concern is the use of a PicKit to program without an additional Vcc connection. Is a "Y" adapter used on the ICSP header? A PicKit can supply very little current (about 30 mA or so). How does the TS know the chip is blank? Was the chip identified by the PicKit and was the programming sequence otherwise normal (e.g., no "overcurrent" warnings)?
 

AlbertHall

Joined Jun 4, 2014
12,345
Please double check the supply and ground circuits. There is still the problem of shorting.

Second concern is the use of a PicKit to program without an additional Vcc connection. Is a "Y" adapter used on the ICSP header? A PicKit can supply very little current (about 30 mA or so). How does the TS know the chip is blank? Was the chip identified by the PicKit and was the programming sequence otherwise normal (e.g., no "overcurrent" warnings)?
Power could be supplied by the red and black wires shown in the first image of this thread. PicKit will detect that voltage and will not attempt to power the board.
 

jpanhalt

Joined Jan 18, 2008
11,087
Power could be supplied by the red and black wires shown in the first image of this thread. PicKit will detect that voltage and will not attempt to power the board.
Mine don't do that. I need to specify how to supply the target; albeit, using an external supply is default.
 

AlbertHall

Joined Jun 4, 2014
12,345
I think the board is upside down.

2 LEDs count (0,1,2,3), so for a 24 h clock, that should be the first digit.
Buttons at the bottom.
Agree that the buttons should be at the bottom.
I think it is intended that the time is read horizontally. Top line 5 LEDs -> hours 0-23. Second line 7 LEDs -> minutes 0-59. Third line seconds as minutes.
 
I think it's more like:

8 0 0 0 0 1
4 0 0 0 0 1
2 0 1 1 0 0
1 1 0 1 0 1

Fast Slow
HH MM

or 12:30:59

The buttons labeled Fast and Slow or HH and MM. You might have a run/hold switch in a better implementation. Generally either run/hold or reset to zero is used so you set the time to the second.
Better, of course, is to have:
run/hold switch, hours, minutes and set seconds to zero
Car clock has HH and MM - 2 buttons.
A clock based on the MM53xx chips built at HP as part of an Explorer's post has: fast/slow, run/stop and increment, I think.
I have a timer that uses fast/slow (center off) and a recessed push button to set the seconds to zero.
It also has a clock set mode that stops the clock.

It would have been cooler if tiny LEDs were used as colons.


Aside:
When programming the clock don;t forget about inter-digit blanking, otherwise the previous digit smears onto the next,
 

ericgibbs

Joined Jan 29, 2010
18,766
hi stobby,
You say the PIC is 'blank' which suggests you have tried to run the project.?
I would recommend that you try to load a simple test program into the PIC, eg: flash one LED.
It is possible that the PIC is faulty and will not program.
The PIC is also soldered into the PCB, with outgoing wires connected directly to the pins, it will be a pain replacing the PIC.
If the PIC fails to program, recover any useful 'bits' and dump the PCB.
E
 

Thread Starter

stobby

Joined Jun 20, 2018
36
Hey Again, I have taken some more detailed photographs of the circuit, The first picture pays particular attention to the push buttons and R2 and R3.
*Red lines = +
*Yellow lines = Pin 2 of switches
*Black box = R2 and R3
PUSH BUTTONS.jpg


The second photo Pays attention to the Transistors, @AnalogKid (As stated above I am unsure of the type of transistor there is no code on them.)
*Blue line Connects to all three transistors Then connects to the blue wire then to VSS
*The Red line Goes to the cathode of first two rows, Then the Anode Of the third row. @AlbertHall (Yes the third row of LED's are definitely facing in Opposite direction I checked with a magnifying glass.) Is it possible they aren't Polarized?
*The Yellow line Highlights the row of LED's facing the opposite direction.
*The Opposing pins of the LED's are numbered. And Have A Green line
Cheers Guys, Brent.
TRANSISTORS.jpg
 

Thread Starter

stobby

Joined Jun 20, 2018
36
@KeepItSimpleStupid Thanks for your Informative post I will take Note of that information for later.

@ericgibbs Hi Eric, The PIC chip is actually sitting in a socket so it is removable, I have many of this Particular chip but the one from many years ago with code has vanished. So this is a brand new chip in the socket, Hence it is blank.

Kind regards, Brent
 

jpanhalt

Joined Jan 18, 2008
11,087
Having a chip simply go blank is a very rare occurrence according to Microchip:

upload_2018-6-23_6-35-41.png

The minimum life expected for program flash memory is 40 years.

Back to my concern expressed in post #23: How did you determine the chip was "blank?" I ask that not to assign blame, but rather to be sure there is a problem that needs to be solved.
 

AlbertHall

Joined Jun 4, 2014
12,345
Having a chip simply go blank is a very rare occurrence according to Microchip:

View attachment 154956

The minimum life expected for program flash memory is 40 years.

Back to my concern expressed in post #23: How did you determine the chip was "blank?" I ask that not to assign blame, but rather to be sure there is a problem that needs to be solved.
It is a new chip. See post #34.
 

jpanhalt

Joined Jan 18, 2008
11,087
It is a new chip. See post #34.
I did read #34, #1 , and all of the others. My question refers to the original chip with a vanishing code. THAT is very unusual. Maybe that happened. But maybe the TS misunderstood some messages while testing it in circuit and took them to mean the chip was blank. Since the chip has been removed, it would be a simple matter to insert in it a solderless breadboard, establish communication with it (use short wires!), and confirm it is blank.

I have never heard of a chip spontaneously losing its program memory in just 7 years if sitting undisturbed. In trouble shooting unusual events, it is far more common for the problem to be human error than equipment error.

John
 
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