[sdiy] dsPIC

[Eric Brombaugh]

On Dec 6, 2008, at 9:00 AM, Seb Francis wrote:

> Eric Brombaugh wrote:
>>
>> I've been using the true-blue Microchip ICD2 (hey - kinda rhymes!)  
>> lately. I tried the Olimex ICD2 knockoff a few years ago, but  
>> switched when I found that it couldn't talk to the 3.3V dsPICs  
>> reliably. It was a few $$ cheaper, but somewhat 'raw'. I've got no  
>> idea what other sorts of low-end interfaces there are these days.
>>
> Which Olimex model did you have Eric?  I use the "PIC-ICD2" model  
> (the one with both USB and RS232 interfaces) and have found it very  
> reliable and fully compatible with flash updates from MPLAB.
>
> I haven't yet tried it with any 3.3V dsPICs, but from the Olimex  
> website it looks like it should be ok (says 2.0 to 6.0 range).  They  
> do state that their PIC-ICD2-TINY model is not ok with newer PICs  
> that require <12.5V for Vpp.

I had the same PIC-ICD2 that you mention - in fact I believe that you  
pointed it out to me before I bought it. It worked just fine for the  
5V 30-series parts that I started out with, but when I tried using it  
with a dsPIC33F128GP708 then I got a lot of failures. Switching to the  
MCHP ICD2 solved the problem and I haven't gone back to try it out  
since then.

I did a bit of research at the time to see what might be wrong and  
recall coming across some discussions on various embedded forums about  
tweaking the values of some resistors to improve current sensing and/ 
or impedance matching. I never looked into it much further though. I  
could probably dig it out and see if there are any firmware updates  
that might fix the problem, or if trying it out on different dsPICs  
might help.

Eric