This is purely for learning and my own development. Now, I know that I have
sufficient time between each pulse since I have it clocking on 1 second
intervals. I am using a 16f84 connected to D0 and D1 of a parport. I manually
step up the MCLR voltage to +12V before I start programming. I have also
monitored every D0/D1 pulse to make sure they coincide with the correct
instructions, and they do. So I must be sending out the wrong instructions in
the wrong order or something, which is why I wish to know the correct process.
I have two leds that connect from D0->GND and from D1->GND. No buffers
involved. I will try removing the led's tho and see what happens. Can you help
me any further?
> On Sun, Jul 21, 2002 at 05:45:27PM -0400, Jai Dhar wrote:
> > HI,
> >
> > I'm trying to code and make my own pic programmer for a 16f84.
>
> Three quick comments/questions:
>
> 1) Is this a learning project or are you building a programmer in prep for
> doing PIC development. If it's the latter then your time is probably better
> spent building/using on of the many programmers and software that's
available.
>
> 2) What is your hardware for programming. The algorithm may not be relevant
> if the hardware for programming is incorrect.
>
> 3) (The usual for me) Have you heard of the 16F628. It's like a 16F84 but
only
> much, much better and much, much cheaper. And it can even help you right
where
> you are because the programmer for it can be simplified vs. a 16F84
programmer.
>
> My programmer and comparison pages can be found here:
>
> http://www.finitesite.com/d3jsys
> http://www.finitesite.com/d3jsys/16F628.html
>
> > As a very simple starting point, I thought I would just try and write any
> >command and read it back to verify it. So I follow this procedure:
> >
> > output 6 bits of 0x2 - 00 0010 (load program data)
> > output a start bit - 0
> > output 14 bits of any command
> > output a stop bit
> > output 6 bits of 0x8 - 00 1000 (cycle program command)
> > output 6 bits of 0x4 - 00 0010 (read program data command)
>
> How long did you wait between the program command and the read program data?
> For the 16F84 you must wait at least 10ms after the beginning of a write
> before you can read.
>
> If possible slow the programming down so that you can see the state of each
> bit as it's transmitted. If possible separate the input into RB7/DATA from
> the output from RB7/DATA with a switch so that you can ensure that the output
> driver comes on when you issue the read.
>
> Are you sure that you are clocking on the correct edge?
>
> There are a lot of issues when first bootstrapping your programming
algorithm.
>
> And as I said before if it's for a learning exercise the great! However if
you
> just want to get the job done, it's probably better to use someone else's
> software.
>
> >
> > After I issue the last command, I cycle the clock 16 times and monitor RB7
> > for voltage changes, and I do'nt get anything. I know I'm sending/clocking
> > RB6 and RB7 correctly because I have led's hooked up. What am I doing
wrong?
>
> Not enough information to determine yet. One last question: are you hooking
> up the LED directly to the RB6/RB7 lines or do you have a buffer between the
> I/O lines and the LEDs. Because if you have the LED hooked up directly it's
> quite possible that they are screwing up your data to and from the PIC.
>
> Hope this helps,
>
> BAJ
>
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>


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