Maybe my source code will help. You can get at it from
www.nti-solutions.org. There's a lovely set of classes I wrote, which
will definitely help you with the algorithm for reading / writing /
erase etc.

> -----Original Message-----
> From: pic microcontroller discussion list
> [mailto:PICLIST@MITVMA.MIT.EDU] On Behalf Of Jai Dhar
> Sent: 23 July 2002 02:31
> To: PICLIST@MITVMA.MIT.EDU
> Subject: [PIC]: PIC programming problems
>=20
> Hi,
>=20
> Despite all the help received, I'm still having problems.. so I will
> explain what I'm EXACTLY doing.
>=20
> I start off with almost 0V on the MCLR pin, and all power off. I
> then apply +5V to Vdd and +12V to MCLR simultaneously. After that, I
> run my program:
>=20
> printf("Issuing write command with data\n");
> sendbyte(6,2,fd);
> sendbyte(1,0,fd);
> sendbyte(8,5,fd);
> sendbyte(6,0x28,fd);
> sendbyte(1,0,fd);
>=20
> printf("Issuing program cycle command\n");
> sendbyte(6,8,fd);
>=20
> printf("Issuing read command\n");
> sendbyte(6,4,fd);
> sendbyte(1,0,fd);
> printf("Reading data now...\n");
> sendbyte(8,0,fd);
> sendbyte(6,0,fd);
> sendbyte(1,0,fd);
>=20
> sendbyte is defined to be a function that sends a certain number of
> bits (I know, naming doesn't make sense) that sends x bits of the
> number specified in the second param.. and yes, it sends  them in
> the correct order. So on the reading data part, I send 6 bits of
> 0x04 to issue a read command, and then a start bit. And then, I send
> out 14 bits of just clocking while reading the pin via parport (the
> sendbyte command also reads the status of RB7). And then finally, a
> stop bit. The CLK and Data lines are passed through a buffer and
> then connected to RB6/RB7, and RB7 also goes to the input of a
> buffer, which goes into the status port of the parport so I can read
> it easily. So.. what seems wrong? I have a feeling now that it's the
> MCLR issue, I'm not sure though. I read the code lowlvl.c, and my
> algorithm is exactly the same after the config. data is entered and
> the PC is incremented. But this doesn't seem that it should matter
> in my simple situation. Ugh.. I'm getting fustrated!
>=20
> Help!!
>=20
> Thanx all,
>=20
> Jai
>=20
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>=20

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