gnupic: RB3/PGM's purpose
Subject:
Re: RB3/PGM's purpose
From:
Byron A Jeff ####@####.####
Date:
6 Nov 2004 16:02:57 +0000
Message-Id: <20041106160253.GA20829@cleon.cc.gatech.edu>
On Sat, Nov 06, 2004 at 03:35:01AM +0100, Antoine wrote:
> Hello
> I just realized my pic serial programmer similar to a JDM one. I had
> some problems during realisation and so had to look different schemas to
> check if mine is good, but finally it's good and works.
> On many schema the RB3 pin isn't wired, as on my programmer, at school
> too we build some projects without (the teacher told us don't wire it
> because we needed pins and it works without, on 16F876cms+LCD
> 4bits+sensor+relay+BPs+...).
Generally the pin needs to be grounded during high voltage programming. Just
to be safe I always suggest grounding the pin through a resistor on the
programmer. Of course when low voltage programming, then the pin is used to
indicate programming mode.
Now in the actual usage of the part it depends on how the part was programmed.
If it's high voltage, then you don't need to do anything special. However for
low voltage programming, the pin must always be grounded during normal
operation. So your instructor must have had you program the part in high
voltage.
So in short: when programming, always ground the pin unless you are using it
for low voltage programming. When using ground the pin if the part is in low
voltage programming mode.
> But by reading the topic PICs on Linux, I just saw on this link
> http://www.finitesite.com/d3jsys that the RB3/PGM pin is wired, so I
> remember me this question for a new time : what is this pin's purpose
> during the programmation ??
That's my page. The purpose of the pin is to allow for low voltage programming
without the +13V programming voltage. But see my notes about: since these
are programmers, the pins should always be grounded during programming unless.
>
> thanks for those who'll answer me.
> PS: If some of you want my schema I provide it, even write a small page
> but I have any space to store it.
> PS2: excuse me for my horrible english, I'm french an write as I can.
I could only wish my French was so well written. 5 ans(!) of Francais down the
drain.
BAJ
