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From: Merciadri Luca on 16 May 2010 11:51
On May 16, 3:17 pm, "Periproct" <Peripr...(a)btinternet.com> wrote:
> "Merciadri Luca" <merciadril...(a)gmail.com> wrote in message
>
> news:ad118bb1-1121-41a3-b83f-8d2810df62a0(a)q23g2000vba.googlegroups.com...
>
> > On May 16, 1:32 pm, "Periproct" <Peripr...(a)btinternet.com> wrote:
> >> I'm trying to program a PIC 16F628A using a Matrix Multimedia HP488
> >> programmer with PPP ver 3.
>
> >> The PIC should be responding to an input on RA4 but it isn't. I suspect
> >> that
> >> the PIC is in low voltage programming mode, hence RA4 is not being used
> >> as
> >> an input.
> >> I have PPP set to disable LVP and I can see bit 7 of the configuration
> >> word
> >> is 0. The book of words says that if I can auto identify the PIC with PPP
> >> it
> >> is in LVP mode which is what I am getting.
> >> The board has the required 14V (I've upped the PSU to get that and the on
> >> board regulator isn't running hot and it is programming the PIC OK).
> > According tohttp://www.voti.nl/swp/, applying a high voltage (around
> > 14V) on the MCLR pin (input only) makes HVP. It seems that it is under
> > LVP, but then?
>
> Thanks for the reply. I'll try and put a meter on MCLR and see if it goes
> high when it programs. Or is it the case I can use a bit of jumper wire to
> apply 14V to that pin and force it to HVP.
I am pretty sure you can.
From: Merciadri Luca on 16 May 2010 11:54
On May 16, 3:19 pm, "Periproct" <Peripr...(a)btinternet.com> wrote:
> Another question is, does it have to be 14V or will a lower voltage be OK..
I think that it should be `around' 14V. I do not know their logic, but
>14 V should be ok. I know, most serial ports provide [-5 ... +12] V,
and it is even lower on laptops.
From: Randy Day on 16 May 2010 12:11
In article <OJCdnRHx4K2fRXLWnZ2dnUVZ8r-dnZ2d(a)bt.com>,
Periproct(a)btinternet.com says...
> I'm trying to program a PIC 16F628A using a Matrix Multimedia HP488
> programmer with PPP ver 3.
>
> The PIC should be responding to an input on RA4 but it isn't. I suspect that
> the PIC is in low voltage programming mode, hence RA4 is not being used as
> an input.
> I have PPP set to disable LVP and I can see bit 7 of the configuration word
> is 0. The book of words says that if I can auto identify the PIC with PPP it
> is in LVP mode which is what I am getting.
> The board has the required 14V (I've upped the PSU to get that and the on
> board regulator isn't running hot and it is programming the PIC OK).
>
> I appreciate it is a long shot someone on here knowing my board and software
> but is there something I'm missing regarding programming this PIC in HVP
> mode so I can get my port RA4 back?

I don't know about your programming setup,
so I can't comment, but when I have an i/o
that won't respond, I usually check for a
missed peripheral control bit setting, such
as A/D, UART, comparator, etc.

Is your RA4 a full i/o, or an output-only
pin? I've been bit by that one occasionally.

IIRC, the clock output of the Pics I use is
multiplexed on RA4, and there are a few
obscure bit settings needed to get it to
function properly as a digital i/o.

Read up on all the functions sharing that
pin, esp. the register settings.

Preset all variables and periph. settings in
code; don't assume registers get set/cleared
consistently at power-up. That way lies
madness.... 8(

HTH.

From: Periproct on 20 May 2010 16:07


"Randy Day" <randy.day(a)sasktel.netx> wrote in message
news:MPG.2659d53e9cb8ca129896b8(a)news.sasktel.net...
> In article <OJCdnRHx4K2fRXLWnZ2dnUVZ8r-dnZ2d(a)bt.com>,
> Periproct(a)btinternet.com says...
>> I'm trying to program a PIC 16F628A using a Matrix Multimedia HP488
>> programmer with PPP ver 3.
>>
>> The PIC should be responding to an input on RA4 but it isn't. I suspect
>> that
>> the PIC is in low voltage programming mode, hence RA4 is not being used
>> as
>> an input.
>> I have PPP set to disable LVP and I can see bit 7 of the configuration
>> word
>> is 0. The book of words says that if I can auto identify the PIC with PPP
>> it
>> is in LVP mode which is what I am getting.
>> The board has the required 14V (I've upped the PSU to get that and the on
>> board regulator isn't running hot and it is programming the PIC OK).
>>
>> I appreciate it is a long shot someone on here knowing my board and
>> software
>> but is there something I'm missing regarding programming this PIC in HVP
>> mode so I can get my port RA4 back?
>
> I don't know about your programming setup,
> so I can't comment, but when I have an i/o
> that won't respond, I usually check for a
> missed peripheral control bit setting, such
> as A/D, UART, comparator, etc.
>
> Is your RA4 a full i/o, or an output-only
> pin? I've been bit by that one occasionally.
>
> IIRC, the clock output of the Pics I use is
> multiplexed on RA4, and there are a few
> obscure bit settings needed to get it to
> function properly as a digital i/o.
>
> Read up on all the functions sharing that
> pin, esp. the register settings.
>
> Preset all variables and periph. settings in
> code; don't assume registers get set/cleared
> consistently at power-up. That way lies
> madness.... 8(
>
Thanks for the reply.
This was a simple little circuit from Elektor so I was just squirting their
HEX into the PIC.
I've been away for a few days so have handed the programmer over to a friend
who has had the same resounding lack of success that I did. As I was doing
it for him he has sent the HEX to an Ebay PIC seller who will program the
PIC for him. He has also ordered a programmed PIC from Elektor. Hopefully
one of them will work and we can backtrack and see what we've been doing
wrong.
I'm off for another week away so the laptop will be going with me as well as
the HEX, ASM and PIC data sheet to keep me amused during the evenings.
Regards.
>
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