Author Topic: Pickit 2 programing a PIC at 5v with 3.3v chips on board  (Read 22197 times)

0 Members and 1 Guest are viewing this topic.

Offline Simon

  • Global Moderator
  • *****
  • Posts: 13920
  • Country: gb
  • Did that just blow up? No? might work after all !!
    • Simon's Electronics
Re: Pickit 2 programing a PIC at 5v with 3.3v chips on board
« Reply #25 on: October 01, 2010, 06:26:03 pm »
just get some single line header strips, break 6 off and solder the ribbon cable to it. I'm aiming to use 90 degree connectors on my boards but in the event I can't get the header near the edge I'd use a cable
https://www.simonselectronics.co.uk/shop
Varied stock of test instruments and components including EEVblog gear and Wurth Elektronik Books.
Also, if you want to get ripped off: https://www.ebay.co.uk/usr/simons_electronics?_trksid=p2047675.l2559
 

Offline Jon Chandler

  • Frequent Contributor
  • **
  • Posts: 541
    • Throw Away PIC
Re: Pickit 2 programing a PIC at 5v with 3.3v chips on board
« Reply #26 on: October 01, 2010, 06:26:59 pm »
At the bottom of this page are a couple options.

This page also shows a trick to deal with female - female cables.
 

Offline Zero999

  • Super Contributor
  • ***
  • Posts: 13171
  • Country: gb
  • 0999
Re: Pickit 2 programing a PIC at 5v with 3.3v chips on board
« Reply #27 on: October 01, 2010, 06:38:18 pm »
I definitely wouldn't trade in my PICkit 2 for a '3 yet.  I suppose I'll be forced to "upgrade" at some point but the features lacking in the PICkit 3 are important to me.

You could skip the 3 and go straight to 4, when it's available, as many people are doing with Windows Vista? Of course I'm not comparing the quality of the PICkit 3 to Vista. ;)
 

Offline Simon

  • Global Moderator
  • *****
  • Posts: 13920
  • Country: gb
  • Did that just blow up? No? might work after all !!
    • Simon's Electronics
Re: Pickit 2 programing a PIC at 5v with 3.3v chips on board
« Reply #28 on: October 01, 2010, 06:48:29 pm »
sounds like a good comparison to me, the best I hear about it is: uh... well.... it supports more chips than 2 does (wonder why that is now) and does the same thing for more money but some of the cool advantages have been removed deliberately !

I understand that it will support chips that 2 cannot but that's about all it seems to have going for it
https://www.simonselectronics.co.uk/shop
Varied stock of test instruments and components including EEVblog gear and Wurth Elektronik Books.
Also, if you want to get ripped off: https://www.ebay.co.uk/usr/simons_electronics?_trksid=p2047675.l2559
 

Offline Veramacor

  • Regular Contributor
  • *
  • Posts: 111
Re: Pickit 2 programing a PIC at 5v with 3.3v chips on board
« Reply #29 on: October 01, 2010, 06:59:57 pm »

The 6th pin on the pickit2 is a no connection right?   El-cheapo uses only 5 pins - that 6th pin is reserved for future use?

here is what I'm used to currently...

 

Offline Simon

  • Global Moderator
  • *****
  • Posts: 13920
  • Country: gb
  • Did that just blow up? No? might work after all !!
    • Simon's Electronics
Re: Pickit 2 programing a PIC at 5v with 3.3v chips on board
« Reply #30 on: October 01, 2010, 07:19:06 pm »
I think it has something to do with the debugger or logic analyser ? not needed for programming
https://www.simonselectronics.co.uk/shop
Varied stock of test instruments and components including EEVblog gear and Wurth Elektronik Books.
Also, if you want to get ripped off: https://www.ebay.co.uk/usr/simons_electronics?_trksid=p2047675.l2559
 

Offline Zero999

  • Super Contributor
  • ***
  • Posts: 13171
  • Country: gb
  • 0999
Re: Pickit 2 programing a PIC at 5v with 3.3v chips on board
« Reply #31 on: October 01, 2010, 07:31:13 pm »
sounds like a good comparison to me, the best I hear about it is: uh... well.... it supports more chips than 2 does (wonder why that is now) and does the same thing for more money but some of the cool advantages have been removed deliberately !

I understand that it will support chips that 2 cannot but that's about all it seems to have going for it
Perhaps someone will design a clone combining both the best of 2 and 3?
 

Offline Simon

  • Global Moderator
  • *****
  • Posts: 13920
  • Country: gb
  • Did that just blow up? No? might work after all !!
    • Simon's Electronics
Re: Pickit 2 programing a PIC at 5v with 3.3v chips on board
« Reply #32 on: October 01, 2010, 07:47:11 pm »
yea it's called keeping 2 up to date and adding the features of 3 to it for the new pics

or get 3 and put all the features back into it
https://www.simonselectronics.co.uk/shop
Varied stock of test instruments and components including EEVblog gear and Wurth Elektronik Books.
Also, if you want to get ripped off: https://www.ebay.co.uk/usr/simons_electronics?_trksid=p2047675.l2559
 

Offline migsantiago

  • Frequent Contributor
  • **
  • Posts: 381
  • Country: 00
    • MigSantiago's Web Site
Re: Pickit 2 programing a PIC at 5v with 3.3v chips on board
« Reply #33 on: October 01, 2010, 08:04:57 pm »

The 6th pin on the pickit2 is a no connection right?   El-cheapo uses only 5 pins - that 6th pin is reserved for future use?

here is what I'm used to currently...

The 6th pin is for other working modes... i.e. Logic Analyzer. It's not used for programming.

Wow... I just reviewed your diagram and you forgot to add the diode for the ICSP mode. That diode prevents current flowing from the 13V at Vpp to the 5V supply. You should implement it as the Pickit2 manual says.
 

Offline scrat

  • Frequent Contributor
  • **
  • Posts: 606
  • Country: it
Re: Pickit 2 programing a PIC at 5v with 3.3v chips on board
« Reply #34 on: October 01, 2010, 08:42:41 pm »
Well, its time to buy the real thing -  I've got a knock-off pickit2 device and that is what is most likely happening - Defaulting to 5v only.
I have a cheap PICkit clone. It did say 5V devices only on the ebay page but I don't have any 3V devices so it isn't an issue for me.

How about using a header and connect the power via jumper, so the PIC's power has to be disconnected before the programmer can be connected? Again probably not much help for your existing board but might be a good way of doing it in future.
I think that a header (with a bunch of diodes and some transistors, gates or comparators) could make the job, translating levels in and out from the PicKit.
Moreover, there are some low-power PICs (for example, one I used, the PIC18F26K20, running at 3.6V max) for which the 12V Vpp is above the abs.max.rating, and they require a protection (usually with a zener diode). With the ICD2 debugger, when you set the device into MPLAB, if it is a low-voltage one it comes out with a warning saying that a protection from the 12V must be put there by the user.
So I think that a good header for level translation and protection would be useful, although easy to make and cheap.

Wow... I just reviewed your diagram and you forgot to add the diode for the ICSP mode. That diode prevents current flowing from the 13V at Vpp to the 5V supply. You should implement it as the Pickit2 manual says.
Maybe I don't catch you, but... How can a 470 Ohm protect from the 12V Vpp, since it will go in series with the 10kOhm pull-up? The diode would be a solution, but I wonder if it is really needed (since the same 10k resistor).
One machine can do the work of fifty ordinary men. No machine can do the work of one extraordinary man. - Elbert Hubbard
 

Offline migsantiago

  • Frequent Contributor
  • **
  • Posts: 381
  • Country: 00
    • MigSantiago's Web Site
Re: Pickit 2 programing a PIC at 5v with 3.3v chips on board
« Reply #35 on: October 01, 2010, 10:25:38 pm »
Wow... I just reviewed your diagram and you forgot to add the diode for the ICSP mode. That diode prevents current flowing from the 13V at Vpp to the 5V supply. You should implement it as the Pickit2 manual says.
Maybe I don't catch you, but... How can a 470 Ohm protect from the 12V Vpp, since it will go in series with the 10kOhm pull-up? The diode would be a solution, but I wonder if it is really needed (since the same 10k resistor).


I don't use the 470 ohm since in my opinion it won't do anything.

I only use the diode which stops a little current flowing to the 5V supply (13V - 5V = 8V across the 10k resistor).

There's people that do not use the 10k resistor. That people must always use the protection diode.
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf