Post by thread:[PIC] 16F287 power connections

Hi. All pins should be connected, that is what they are there for. I thought the datasheet was clear on that point, maybe not. :-) Jan-Erik. Goran Hosinsky wrote 2012-05-21 09:14: > Must VDD and VSS be connected to both sides of the 40 pin 16F887 or is > one side enough? VDD is on pin 11 and 32, VSS on 12 and 31. > Goran, Canary Island

At 09.14 2012.05.21, you wrote: >Must VDD and VSS be connected to both sides of the 40 pin 16F887 or is >one side enough? VDD is on pin 11 and 32, VSS on 12 and 31. If we believe Microchip (and we only have good reasons to) You MUST connect all of them EVEN JUST FOR PROGRAMMING!

Electron wrote: > At 09.14 2012.05.21, you wrote: > >> Must VDD and VSS be connected to both sides of the 40 pin 16F887 or is >> one side enough? VDD is on pin 11 and 32, VSS on 12 and 31. >> > > If we believe Microchip (and we only have good reasons to) You MUST connect all of them EVEN JUST FOR PROGRAMMING! > > And if we believe our lying eyes, we will see that only 1 VDD and 1 VSS need to be connected! Kerry

Thanks! I would say that the problem is not the datasheet but my reading of the 300+ pages. Goran On 2012-05-21 09:46, Jan-Erik Soderholm wrote: {Quote hidden}> Hi. > > All pins should be connected, that is what they are there for. > I thought the datasheet was clear on that point, maybe not. :-) > > Jan-Erik. > > > Goran Hosinsky wrote 2012-05-21 09:14: >> Must VDD and VSS be connected to both sides of the 40 pin 16F887 or is >> one side enough? VDD is on pin 11 and 32, VSS on 12 and 31. >> Goran, Canary Island

At 10:53 AM 5/21/2012, you wrote: >Thanks! I would say that the problem is not the datasheet but my reading >of the 300+ pages. >Goran I'm not sure it's in there anyhow. Certainly not in the 16F287 datasheet. ;-)

At 10:46 AM 5/21/2012, you wrote: >Electron wrote: > > At 09.14 2012.05.21, you wrote: > > > >> Must VDD and VSS be connected to both sides of the 40 pin 16F887 or is > >> one side enough? VDD is on pin 11 and 32, VSS on 12 and 31. > >> > > > > If we believe Microchip (and we only have good reasons to) You > MUST connect all of them EVEN JUST FOR PROGRAMMING! > > > > >And if we believe our lying eyes, we will see that only 1 VDD and 1 VSS >need to be connected! > >Kerry It's one of those things like running a PIC on a solderless breadboard with an external crystal and without a ceramic bypass cap- it usually works, but probably compromises a few things.

At 08:46 AM 5/21/2012, Kerry Wentworth wrote: > > If we believe Microchip (and we only have good reasons to) You > MUST connect all of them EVEN JUST FOR PROGRAMMING! > > >And if we believe our lying eyes, we will see that only 1 VDD and 1 >VSS need to be connected! Yeah - but its one of those things that can so easily bite you when you least expect it. Great rule of thumb: if you want the highest-possible reliability, even when programming, do connect all Vss and Vdd pins to their proper nodes. dwayne -- Dwayne Reid <spam_OUTdwaynerTakeThisOuTplanet.eon.net> Trinity Electronics Systems Ltd Edmonton, AB, CANADA (780) 489-3199 voice (780) 487-6397 fax http://www.trinity-electronics.com Custom Electronics Design and Manufacturing

Dwayne Reid wrote: {Quote hidden}> At 08:46 AM 5/21/2012, Kerry Wentworth wrote: > > >>> If we believe Microchip (and we only have good reasons to) You >>> >> MUST connect all of them EVEN JUST FOR PROGRAMMING! >> >> And if we believe our lying eyes, we will see that only 1 VDD and 1 >> VSS need to be connected! >> > > Yeah - but its one of those things that can so easily bite you when > you least expect it. > > Great rule of thumb: if you want the highest-possible reliability, > even when programming, do connect all Vss and Vdd pins to their proper nodes. > > dwayne > > Well, unless you are making a quick breadboard, or your PCB is so crowded you can't get a ground to the second VSS pin, there is really no good reason to NOT connect both. And sure as shootin', somebody will use a chip with an analog and a digital ground, and decide that both don't need to be connected. ('cause I said so!) and it won't work. So yeah, both SHOULD be connected. But they don't HAVE to be, which was the question. Kerry

IVP wrote: >> both SHOULD be connected. But they don't HAVE to be, >> which was the question >> > > Distance of an I/O or OSC pin from Vss or Vdd could/will have > consequences won't it ? > Possibly. I don't know about the 16F287 in the subject line, but the question I answered was about the 16F887. The 2 ground pins are connected together inside the chip, as are the 2 VDD pins. So, how far is a VDD pin from the power supply? 1"? 3"? 10"? And the 2nd VDD pin is another .3". Does it really matter? For that matter, if both are connected, it is possible the board will end up designed such that all other circuitry draws its power through the internal PIC connection. That would also have an effect. And 2 VSS pins would form a ground loop, also having an effect. Good design must take many things into account. Kerry

Ah, so you are the one who read it all then! You must tell me what it says someday. -Jim -----Original Message----- From: .....piclist-bouncesKILLspam@spam@mit.edu [piclist-bouncesKILLspammit.edu] On Behalf Of Goran Hosinsky Sent: 21 May 2012 15:53 To: Microcontroller discussion list - Public. Subject: Re: [PIC] 16F287 power connections Thanks! I would say that the problem is not the datasheet but my reading of the 300+ pages. Goran On 2012-05-21 09:46, Jan-Erik Soderholm wrote: {Quote hidden}> Hi. > > All pins should be connected, that is what they are there for. > I thought the datasheet was clear on that point, maybe not. :-) > > Jan-Erik. > > > Goran Hosinsky wrote 2012-05-21 09:14: >> Must VDD and VSS be connected to both sides of the 40 pin 16F887 or is >> one side enough? VDD is on pin 11 and 32, VSS on 12 and 31. >> Goran, Canary Island