Hi again
----- Original Message -----
From: "Byron A Jeff" <byron@CC.GATECH.EDU>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Saturday, August 25, 2001 1:36 AM
Subject: Re: [PIC]: converting linuxpp to 16f87x

Andy:
> > > > I saw that BAJ said
that(http://piclist.com/techref/microchip/16F877/taitlinux.htm):
> > > > "The final patch to picprg 2.2 is changing the 0x08 begin
programming command in lowlvl.c to 0x18, which is the 16F87X equivalent."
> > > >
> > > > I tried that but it still couldn't erase my new 16f876...

BAJ:
> > > Oh that was long ago! We've had several threads since then on the
subject.
> > >
> > > Let me suggest you try my trivial programmer. Essentially it's the
Tait
> > > programmer with all of the high voltage stuff removed. Only does low
voltage
> > > programmer. It's been tested with the 16F87X series and the 16F628. My
> > > development environment is Linux based but as long as the software has
> > > configurable pins, anything should work:
> > >
> > > http://www.finitesite.com/d3jsys
> >

Andy:
> > I've seen your page, but no idea how it helps me.
> >
> > I want to use HVP so i can use RB3..


BAJ:
> Sometimes I know the feeling. I really wish that Microchip could have
found
> one end or the other of Ports A-C to stick LVP on. I don't really miss the
pin
> but its location sucks.

> But usually I've found it just isn't worth the effort. While 5V is easily
> findable on a PC, that 12V signal usually is only available from either
the
> serial port or a disk connector. Point is that you have to hunt it up.

Already have a supply for it.....

Andy:
> > My circuit is directly connected on the data and clock, and MCLR is
> > controlled by a NPN transistor.

BAJ:
> I'd advise that you actually measure the output voltage of your parallel
port.
> This is where my page does really help. I've noticed that modern ATX
> motherboards will often only output a high of 3.3V to the parallel port.
> Perfectly legal since a TTL high signal only need be 2.0V. But by spec the
> PIC must be programmed with a Vcc of 5V. And at that voltage 3.3V is
undefined.
> An input must be a minimum of 0.8Vcc to be considered high and at 5V that
> value is 4V.

Well, I tested to see how much voltage my parralel port puts out and it *is*
4.9V...(Pentium I 133 AT...(linux server))

> You'll probably need a HCT part as I describe on my page in order to
guarantee
> the proper signal level. It'll convert that 3.3V TTL high in into a CMOS
Vcc
> out. You'll probably have the same issue with the transistor not snapping
> completely on.

I don't think I do *especially* when it programs 16f84a's fine!

> As soon as I added the HCT part on my trivial programmer it started
working
> like a champ. It also guarantees that your programmer will work with any
> parallel port.

I can try it but i dont think it will matter...

Andy
> BAJ

Now I have to go buy a HCT gate at radioshack

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads