Wouter van Ooijen wrote:
>>> For an ICSP programmer it makes of course sense to draw the 
>>>       
>> power from
>>     
>>> the target itself.
>>>       
>> But then the programmer can't control Vdd, which is necessary for some
>> chips.  In many instances a hobby programmer can get away 
>> with using target
>> Vdd, but serious professional programmers can't afford to do that.
>>     
>
> ICSP and variable-voltage verification is a shaky combination anyway....
>
> BTW: which chip require variable Vdd for programming (!= for
> verification)?
>   
NOBODY requires that for hobbyist use. The main problem is that USB 
ports are allowed to drop their
voltage to 4.3V legally, and while most PICs will program at that 
voltage, few will execute a bulk-erase, which is
the main problem with most USB programmers.

--Bob

> Wouter van Ooijen
>
> -- -------------------------------------------
> Van Ooijen Technische Informatica: www.voti.nl
> consultancy, development, PICmicro products
> docent Hogeschool van Utrecht: www.voti.nl/hvu
>  
>
>   
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