New comer EEPROM porgraming problem

[Frank]

Hi Brad

I found your website when browsing through some DIY electronic projects on the internet, and started building your 8x85 POV display.

The problem that I'm facing is that after I programmed the PIC16F648A using the MPLAB IDE, and then when trying to program the EEPROM using the PICKIT2 ver. 2.5 with the excel spread sheet that I drew "Happy New Year" with, and saved the .hex file with HxD, it shows me some error.

I've only got the PicKit2, is there another way to program the eeprom without having to buy a separate programmer?
(because i am cheap )
and the last problem that i encountered was that i got the common annode LED's the same as another post earlier in this forum. i tried in your tutorials and found that they get switched on with a logic 0 if i connect the annode to a +5v and sink the current. If i try to build your one chip POV display how do i change the codes to instead of sending out a logic 1, to send out a logic 0? i really hope i don't need to throw these LED's away and buy the common cathode ones.
(because again i am cheap )

i really love your website and all your videos, and i hope these questions make sense

Thank you in advance
Frank

[bitfogav]

Hi Frank, welcome to the forum..

Do you mean you are trying to programme the 27C512 / 27E512 EPROM?, if this is the case then the PicKit2 doesnt support this type of Eprom, you will need to get a Eprom programmer that will programme the 27C512/27E512, one thing to watch though is that the cheap ones come with a parallel port connection, so make sure your PC supports this, but there are USB eprom programmers out there but they seems to be more expensive, always check the specs of the eprom programmer and make sure that it will programme the 27C512/27E512.

[brad]

Hi Frank

Just as bitfogav was saying, unfortunately you can't program eeproms / eproms with the pickit2. the eeproms used in the project use an 8-bit parallel data bus whereas the pickit2 has a serial interface.

So you can either buy a programmer on ebay for maybe $30 - $40? or you could make the one chip POV which is a much simpler design, has better conversion software and only requires one pic chip.

As for your common anode LED's they are fine to use. As you say, you need to connect all the anodes to +5V and then a logic 0 will turn each one on. In the code, a logic 1 is sent out each time we want to turn an LED on, so all we need to do is invert this data.

to do this in assembly you just need to follow this previous post:

viewtopic.php?f=20&t=33&hilit=invert

Although I just read that you were looking to do this for the one chip POV (which is programmed in basic) so you need to do this:

Let's say you were sending out 1 byte of red data called RedData. and let's say that RedData contained 00110100.

Instead of sending it to the LED's (let's pretend they are connected to PORTB) like this:

Code: Select all

PORTB = RedData

You would need to invert the data so you just need to modify it like this:

Code: Select all

PORTB = RedData Xor %11111111

Hope that helps!

[Frank]

Thanks very much guys, and happy new year!

I have started with building the one chip POV display yesterday,
but just a quick question, please bare with me if it sounds dumb,
where does the 5v regulator (7805) go in the circuit diagram?

Thanks again, I'm planning to put this POV display on top of a helmet
so I can draw a weird animation and scare my little nephew.
I'll keep you guys updated on the progress, and also maybe post his reaction face here.

[bitfogav]

Frank your project sounds cool, any question is welcome here and were a bunch of helpful guys!

To connect up the power regulator you need to connect the VCC connection on the regulator to the other VCC connections on the schematics, heres a better example of connecting the regulator, hope this helps. the INPUT goes to your main power supply (positive +) connection for example a 9volt battery. Also if you are using common annode LED's then make sure you connecting them to VCC aswell and not ground.

OneChipPOVpower.jpg (10.37 KiB) Viewed 30823 times

[brad]

Yep, just further to what bitfogav was saying. The 7805 is a 5 volt regulator that gives us a constant 5volts delivered to the circuit even under varying load situations (E.G. sometimes there will be more LED's on than at other times) If we didn't have a regulator, this 5 volts could (and would) go up and down depending on what the circuit was actually doing.

The capacitors are not critical because the power supply you are using would most certainly have capacitors in it (used for filtering) or if you are using a battery then I don't see the need for these capacitors either because the battery gives a nice steady dc voltage.

so all you really have is an input, an output and then the middle pin which is ground which both the input and output connects to.

[Bealyn]

I have already started construction of a chip POV
5V regulator (7805) Where is the circuit diagram in?
I will continue to update the progress, you may also be the face of his reaction here.

[brad]

I have already started construction of a chip POV
5V regulator (7805) Where is the circuit diagram in?
I will continue to update the progress, you may also be the face of his reaction here.

Hi, the 7805 regulator has three connections. You will need to connect the power supply (which should be at least 7.5 volts) to the input and ground connections. You then connect the output and ground connections to the POV circuit - this will give it a nice and steady +5V for the circuit to run!