peter green wrote:
>> I was under the impression that in-circuit programming was LVP (low
>> voltage programming).  Is that not the case?  Even so, ICSP uses some
>> pins that cannot be used for I/O and I have already done projects where
>> I needed every available I/O pin.  So I need a programmer with high
>> voltage programming.  What I'm hoping is to be able to get one that does
>> both instead of having to get two programmers.
>>   
> Your impressions are rather wrong
> 
> Pics are always programmed serially. Whether they are sitting in a 
> target circuit or a socket dedicated to programming is generally 
> irrelvent to the programmer circuit. Hardly any programmers use LVP, it 
> wastes an IO pin on the target device and leaves a much greater 
> possibility of the device going into program mode inadvertantly during 
> normal operation. Really the only advantage of LVP is it saves on parts 
> in the programmer.
> 
> There is no reason you can't use every IO line and program in circuit. 
> Resistors can be added such that the programmer and pic can control the 
> line during programming but the line can be used as an input or low 
> power output when the circuit is in use. If you decide to disable MCLR 
> programming gets a little tricker because the programmer needs to 
> control VDD to get such chips into program mode but there are 
> programmers that can control VDD and provide sufficiant current to drive 
> a large target circuit (for example olin's proprog).

Ok, I'm remembering some more now - it's been a number of months since I
looked into programmers last and I knew way less about PIC chips then
than I do now (which is still not a fantastic lot).  I think the main
problem I had was that I had to disable MCLR and couldn't program the
chip using ICD2.  The melabs programmer works just fine for that.  I was
confusing LVP with ICSP, and it is ICSP I couldn't do (at least with the
ICD2) with MCLR disabled.

Thanks for the information.
Moses
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