On 2012-01-31, Paul <paul@pcserviceselectronics.co.uk> wrote:> In article <jg7d1i$fmq$1@dont-email.me>, > clubley@remove_me.eisner.decus.org-Earth.UFP says... >> >> BTW, where do you buy your boards from in the UK ? >> >> Two distributors are listed for the UK; Active Robots and Proto-Pic, >> neither of which appears to sell this type of board: > > I have used Active Robots as my source a few times over the years. > Generally spoke to them on the phone, helpful bunch of folks. > >> http://www.schmartboard.com/index.asp?page=products_smttodip&id=451 > > Give them a ring and ask them, they also distribute Sparkfun so you > avoid customs and import paperwork, if that is an issue for you. >Thanks. I've been in touch with them and am waiting to hear back from them on pricing. (And yes, customs is a major importing issue as far as I am concerned. :-))>> A question about this product is the placement of decoupling capacitors >> and crystal (thanks to whoever pointed this out) next to the MCU >> instead of on the baseboard which the adapter would plug into. >> >> For the people here who have actually used this product, how did you >> solve this problem ? > > I have used the square boards and put decouplers usually 0805 or 0603 > caps on the corner SMT mounting pads, sometimes a few pullups there as > well. > > Generally my projects involve many clocks and often I have external > oscillator solution (a few gates and quartz as not too high frequency) > this works best as often same clock or subclock is needed eleswhere > so instead of multiple crystals I run the buffered clocks around the > board. In one case I needed one 12 MHz and two 6MHz so I created a > master 12MHz oscillator at 3V3 uning picogates, fed into PLD and did > divide by 2 in there and then ran 6MHz from 2 picogate buffers. The > two buffers were for a 5V and 3V3 clock. A few picogates uses less > space than multiple cystals. > >> >> Did you use the spare pads provided on the board and was this sufficiently >> close to the MCU manufacturer's specifications to work ok ? > > For caps it was, not normally enough room for a crystal, so buffered > clock drive was easier. >Thanks for the detailed design notes (and thanks for the example photograph in your other posting). It helps me to understand how you are using the boards. Thanks, Simon. -- Simon Clubley, clubley@remove_me.eisner.decus.org-Earth.UFP Microsoft: Bringing you 1980s technology to a 21st century world
ARM (or other 32 bit) MCUs in PDIP ?
Started by ●January 27, 2012
Reply by ●January 31, 20122012-01-31
Reply by ●February 3, 20122012-02-03
Hi, Mel. Thanks for jumping in. On Tue, 31 Jan 2012 11:08:17 -0500, Mel Wilson <mwilson@the-wire.com> wrote:> Frnak McKenney wrote: > >> This should leave a "trough" that the TSOP-8 (or whatever) lead >> can lie in, and this will help keep the IC from moving about as >> much as it would on an unaltered pad. > > On the board I'm looking at, the SMT pads are the same width as > the leads. A routed trough that leaves any copper on the board > at all will be too narrow for the lead. ...Oh.> ... There isn't a lot of > room to widen that pads either. (Really covet one of those > AdaFruit USB microscopes right now.) Risk solder bridges or > frying the infinitesimal copper strips off the board during > rework. From what I've read, the current scheme of things > counts on the surface tension of the melted solder to pull the > part into alignment.... "Nevermind!" (*) This is probably what linnix was trying to tell me. (Sorry about that!) For what it's worth, I have one of those USB 'scopes, and it takes really nice pictures, but it does have a few drawbacks for someone who wants to use it in place of an assembly/inspection microscope. First, it's hard to focus: the "knurled" focus adjustment is stiff and tends to shift the microscope while you adjust it. It's often easier to set the focus, then move the microscope around to get the view you want. Second, it's light, and unless you're extremely careful it gets bumped so the object being disappears out of frame. Hand-held pictures are not impossible, but tricky without an arm rest. I've been meaning to build something out of an old gooseneck lamp, but haven't gotten "a round tuit" yet. If you're curious, you can find a number of USB microscopes here: http://www.bhphotovideo.com/ Just do a search on... well, "usb microscope". <grin!> Frank (*) http://en.wikipedia.org/wiki/Emily_Litella -- The study of history is a painful antidote to contemporary arrogance. It is humbling to discover how many of our glib assumptions, which seem to us novel and plausible, have been tested before, not once but many times and in innumerable guises; and discovered to be, at great human cost, wholly false. -- Paul Johnson -- Frank McKenney, McKenney Associates Richmond, Virginia / (804) 320-4887 Munged E-mail: frank uscore mckenney aatt mindspring ddoott com
Reply by ●February 3, 20122012-02-03
On Sun, 29 Jan 2012 11:58:32 -0600, Frnak McKenney wrote:> This is a branch from the "ARM (or other 32 bit) MCUs in PDIP ?" thread. > > On Sat, 28 Jan 2012 17:23:01 -0500, Rich Webb > <bbew.ar@mapson.nozirev.ten> wrote: >> On Sat, 28 Jan 2012 15:14:45 -0600, Joe Chisolm >><jchisolm6@earthlink.net> wrote: > > [...] > >>>SchmartBoard has a line of adapters. Easy to work with. Never had any >>>issues ordering from them. >>> >>>http://www.schmartboard.com/index.asp?page=products_smttodip >> >> One feature of the Schmartboard is their "ez technology" which puts the >> SMT leads onto recessed pads, so they sort of "fall into place." Can't >> get much easier... > > I took a look at their three-minute video: > > http://www.schmartboard.com/index.asp?page=movie > > and it looks like a neat technique. I wonder if it could be > approximated by creating "Y"-shaped pads like these: > > > Top View > > /---------------------------------\ > / | > / Pad | > ---- /----------------------------/ +---------------- > | | > | | Lead > ---- \----------------------------\ | > \ | +---------------- > \ | > \---------------------------------/ > > +---------------- > | > Side View | Lead > | > +---------------- > -----------------------------------------+ > Pad | > -----------------------------------------+ > > where the copper shape and thickness itself provided the "trough"? The > "trough" might not be as deep as the ones manufactured by SchmartBoard, > but all it has to be is "good enough". > > Assuming that pads could be etched / deposited with a narrow enough > width and not present other problems (current capacity, etc.), this > might be accomplished by a simple (and possibly automated) edit of the > appropriate component libraries. > > ( Heck, a suitable ALIDHTBI 3D CNC machine could "rout"-out > troughs, lay down a thin layer of conductive paint, and even drill > holes for a few through-hole components! ) > > Jes' curious...It sounds like an excellent solution to a nearly-nonexistent problem. I have no trouble soldering 0.5mm pitch parts onto bare (no solder mask) boards; while I have the advantage of an assembly microscope, even before I got it I could still get the job done with a watchmaker's loupe and some care taken. You just tack down the corners of the chip, goober solder on all over everything without worrying about solder bridges, then use desoldering braid to remove all the bridges you just created. That seems "schmarter" than using someone else's prototyping board, to me. -- My liberal friends think I'm a conservative kook. My conservative friends think I'm a liberal kook. Why am I not happy that they have found common ground? Tim Wescott, Communications, Control, Circuits & Software http://www.wescottdesign.com
Reply by ●February 6, 20122012-02-06
On Sat, 28 Jan 2012 23:00:34 +0000, Simon Clubley wrote:> On 2012-01-28, Mark Borgerson <mborgerson@comcast.net> wrote:>> If you can print legibly, your hands are probably steady enough. A >> good binocular microscope is handy for more than soldering and >> shouldn't cost more than $300. > > While such a microscope would be affordable, for me, that would count as > a investment I would not want to make until I was sure of myself.While a nice binocular microscope with large field of view and focal distance, and perhaps with long and movable arm is expensive, I am using a ghetto microscope that I got on Ebay for $30. I use it for electronics and for ton of other household tasks (splinter removal and other domestic surgeries), probably at least once a week over last several years. One of the better tool investments I made. I don't see it now for the price I got it from, but it is almost exactly like this one: http://www.ebay.com/itm/Inspection-Binocular-Microscope-Coin-Rock-Stamp- Circuit-/200279748681?pt=LH_DefaultDomain_0&hash=item2ea19a7049
Reply by ●February 6, 20122012-02-06
On Sat, 28 Jan 2012 23:00:34 +0000, Simon Clubley wrote:> On 2012-01-28, Mark Borgerson <mborgerson@comcast.net> wrote:>> If you can print legibly, your hands are probably steady enough. A >> good binocular microscope is handy for more than soldering and >> shouldn't cost more than $300. > > While such a microscope would be affordable, for me, that would count as > a investment I would not want to make until I was sure of myself.While a nice binocular microscope with large field of view and focal distance, and perhaps with long and movable arm is expensive, I am using a ghetto microscope that I got on Ebay for $30. I use it for electronics and for ton of other household tasks (splinter removal and other domestic surgeries), probably at least once a week over last several years. One of the better tool investments I made. I don't see it now for the price I got it from, but it is almost exactly like this one: http://www.ebay.com/itm/Inspection-Binocular-Microscope-Coin-Rock-Stamp- Circuit-/200279748681?pt=LH_DefaultDomain_0&hash=item2ea19a7049
