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ARM (or other 32 bit) MCUs in PDIP ?

Started by Simon Clubley January 27, 2012
On 2012-01-27, hamilton <hamilton@nothere.com> wrote:
> Hello Simon, > > Please do not take this badly, >
I won't; it's a fair question.
> > Why is dip the only game you want to play ?? >
Because up until now, it's been sufficient for my projects. As I mentioned in another post, I suspect I am going to have to move to using breakout boards in the future. Simon. -- Simon Clubley, clubley@remove_me.eisner.decus.org-Earth.UFP Microsoft: Bringing you 1980s technology to a 21st century world
On Saturday, 28 January 2012 09:05:23 UTC, Simon Clubley  wrote:
> As I mentioned in another post, I suspect I am going to have to move > to using breakout boards in the future. >
I would also like to ask, why not use one of the breakout boards now? People often ask similar questions, and it generates a lot of answers, but without much feedback on what the "stopper" is. Is it cost? Complexity? Availability? Unfamiliarity? Cost of tools? I have no real idea, which makes it hard to tailor future suggestions. One problem I see is that a lot of breakout boards are quad package, or dual row, which is not convenient for stripboards. Or they are DIP package, but have a lot of extras added, which bumps up the cost and forces you into specific design choices. I suspect what people really want, is just a chip on a DIP board, as cheaply as possible. There is little profit in that, and hundreds of possible chips, so it is unlikely to attract commercial interest. BatchPCB makes it really easy for people to order bare boards, so that is half the job. The other half is finding an enterprising amateur willing to provide a soldering service for a few $.
On Sat, 28 Jan 2012 04:15:38 -0800 (PST), Bob
<bobcousins42@googlemail.com> wrote:

>The other half is finding an enterprising amateur willing to provide a soldering >service for a few $.
Or bite the bullet and learn to DIY. Once one has gotten past the scary place of a side by side comparison between a 0.1" DIP and 0.5 mm TQFP, it turns out that surface mount work is remarkably easy. The how-to videos over at Sparkfun and Dave's EEVBlog provide good demonstrations. <http://www.sparkfun.com/tutorials/category/2> <http://www.eevblog.com/2011/07/18/eevblog-186-soldering-tutorial-part-3-surface-mount/> -- Rich Webb Norfolk, VA
It's great that you find it remarkably easy, but did you stop to think that some
people with failing eyesight and unsteady hands may have also tried it and found
it remarkably difficult?
On 2012-01-28, Bob <bobcousins42@googlemail.com> wrote:
> On Saturday, 28 January 2012 09:05:23 UTC, Simon Clubley wrote: >> As I mentioned in another post, I suspect I am going to have to move >> to using breakout boards in the future. >>
You ask a series of good questions. I will try and answer them in detail below.
> > I would also like to ask, why not use one of the breakout boards now?
Simply because the trade off with the issues I mention below versus the wide-ranging availability of PDIP parts means that (for projects for which PDIP parts are available) I prefer to use those PDIP parts. For something which requires a ARM7 (and above) processor, I just buy a board from somewhere like Olimex.
> People often ask similar questions, and it generates a lot of answers, > but without much feedback on what the "stopper" is.
I understand. Below is my current thinking on the questions you ask.
> Is it cost? Complexity? Availability?
The breakout boards I see have a whole lot of extras added onto them which are of no interest to me and just bump up the price and size. A number of them are also designed as standalone units instead of something which can be plugged into a stripboard/veroboard base unit. In that case, you have to work with what is on the board, instead of been able to build your own circuit around it. Complexity is not a issue in that I can just ignore the parts of a board I don't need. Availability is not really a issue; they tend to be freely available here in the UK. When I get a idea for something, I like to be able to design something which contains just the components I need, and nothing else. There's also the fact that projects could involve more than one breakout board, which rapidly starts multiplying the price difference. Therefore, this leaves the option which we have been discussing which is having some bare generic adapter templates made which, when populated, would contain nothing but the IC in question plus the 0.1 inch pitch pinouts. The price of having custom boards made is not really too much of a issue for me. For designing them, I would just use gEDA and the cost of a batch of boards does not seem too bad (at least the last time I looked). The real problem with this, and this is the core problem here, is working with components that small. I don't currently have the skill set required for that and I am not sure what extra equipment is required in case I need help soldering something that small in case my hands are not steady enough.
> Unfamiliarity? Cost of tools?
Cost of development tools for software development is not a problem. For the hardware side of things, I just use a low cost JTAG tool for the ARM boards (a Wiggler clone from Olimex) and I built a programmer for the AVRs which I use with AVRdude. On the software side of things, both for AVR and ARM, I just use a open source toolchain (gcc/binutils and, for the ARM boards, OpenOCD/gdb/ddd). I don't need any of the handholding stuff which you see in the commercial toolchains. I just write my own headers (using the datasheet) if they are not available or the manufacturer uses coding conventions I disagree with. Likewise, on the ARM, I am now using my own startup code template, which I alter based on the manufacturer's documentation and any issues raised by the manufacturer supplied startup code (which I just view as documentation for things which should have been in the datasheet/reference manual but wasn't :-)). Unfamiliarity isn't really a major problem in a number of cases, but it depends on the degree of unfamiliarity. Learning another ARM MCU isn't a problem. Learning a completely new architecture (ie: MIPS) requires a far larger amount of time to be available. Assuming I had the time on a specific project, I would take the lack of familiarity as a opportunity to learn something new.
> I have no real idea, which makes it hard to tailor future suggestions. > > One problem I see is that a lot of breakout boards are quad package, or > dual row, which is not convenient for stripboards. Or they are DIP package, > but have a lot of extras added, which bumps up the cost and forces you into > specific design choices. I suspect what people really want, is just a chip > on a DIP board, as cheaply as possible. There is little profit in that, and > hundreds of possible chips, so it is unlikely to attract commercial interest.
This is exactly the problem. I am quite capable of building my own circuits provided the parts are in a size I can work with. I am not interested in breakout boards that are loaded with a whole set of parts which bump up the size and price.
> BatchPCB makes it really easy for people to order bare boards, so that is > half the job. > The other half is finding an enterprising amateur willing to provide a > soldering service for a few $.
Thanks for the pointer. BTW, when I finally go down this route, it will be me doing the soldering as I will regard it as another skill to be learnt. :-) I hope this helps you understand the issues I consider and the priority I assign to each type of issue. Simon. -- Simon Clubley, clubley@remove_me.eisner.decus.org-Earth.UFP Microsoft: Bringing you 1980s technology to a 21st century world
Simon Clubley <clubley@remove_me.eisner.decus.org-Earth.UFP> writes:


[...]

> > When I get a idea for something, I like to be able to design something > which contains just the components I need, and nothing else. There's > also the fact that projects could involve more than one breakout board, > which rapidly starts multiplying the price difference. > > Therefore, this leaves the option which we have been discussing which is > having some bare generic adapter templates made which, when populated, > would contain nothing but the IC in question plus the 0.1 inch pitch > pinouts. > > The price of having custom boards made is not really too much of a issue > for me. For designing them, I would just use gEDA and the cost of a batch > of boards does not seem too bad (at least the last time I looked). > > The real problem with this, and this is the core problem here, is working > with components that small. I don't currently have the skill set required > for that and I am not sure what extra equipment is required in case I need > help soldering something that small in case my hands are not steady enough.
Hi Simon, If you search the archives for this group and perhaps sci.electronics.design and sparkfun you will see lots of advice/tutorials on soldering surface mount chips. But basically the key ingredients are - bright light - magnification (e.g. headband magnifier) - flux (which is in the solder but only lasts a few seconds) I don't find steady hands to be an issue; you just rest them on the work surface, [...]
> > BTW, when I finally go down this route, it will be me doing the soldering > as I will regard it as another skill to be learnt. :-) > > I hope this helps you understand the issues I consider and the priority I > assign to each type of issue. > > Simon.
-- John Devereux
On Jan 28, 8:29=A0pm, Simon Clubley <clubley@remove_me.eisner.decus.org-
Earth.UFP> wrote:
> ... > The real problem with this, and this is the core problem here, is working > with components that small. I don't currently have the skill set required > for that and I am not sure what extra equipment is required in case I nee=
d
> help soldering something that small in case my hands are not steady enoug=
h. I seriously doubt you would have a problem soldering SMT boards, it is probably just a matter of being a bit daring the first time. You will discover it will cost you much *less* time and effort; put the solder paste on the board, place the parts then bake in a kitchen oven (I use a $100 2kW one, of those small ones, sort of microwave oven sized). Get an IR thermometer and you will be equipped well enough. Oh, and for rework you will need two soldering irons, that is how I do it at least. I also have a blower (hot air station, I believe), but I have been getting away without having one in the past. And I manage boards like this one more or less routinely: http://tgi-sci.com/misc/nmc3top.gif Dimiter ------------------------------------------------------ Dimiter Popoff Transgalactic Instruments http://www.tgi-sci.com ------------------------------------------------------ http://www.flickr.com/photos/didi_tgi/sets/72157600228621276/
In article <30778030.282.1327757815830.JavaMail.geo-discussion-
forums@vbbfd4>, bobcousins42@googlemail.com says...
> > It's great that you find it remarkably easy, but did you stop to think that some > people with failing eyesight and unsteady hands may have also tried it and found > it remarkably difficult?
I solved the failing eyesight part many years ago with a $300 binocular microscopy. I haven't reached the shaky hands stage yet, so I keep on soldering those TQFPs. OTOH, I find doing that soldering for more than an hour or two a bit boring, so I hired my teenage kids at well above minimum wage and well below what it costs to hire a part-time technician (~$21/hr). They still complain about the repetitive nature of 100 pins of 0.1" headers, but the attraction of gas and movie money usually wins. Mark Borgerson
In article <jg1er7$md3$1@dont-email.me>, 
clubley@remove_me.eisner.decus.org-Earth.UFP says...
> > On 2012-01-28, Bob <bobcousins42@googlemail.com> wrote: > > On Saturday, 28 January 2012 09:05:23 UTC, Simon Clubley wrote: > >> As I mentioned in another post, I suspect I am going to have to move > >> to using breakout boards in the future. > >> > > You ask a series of good questions. I will try and answer them in detail > below. > > > > > I would also like to ask, why not use one of the breakout boards now? > > Simply because the trade off with the issues I mention below versus the > wide-ranging availability of PDIP parts means that (for projects for > which PDIP parts are available) I prefer to use those PDIP parts. > > For something which requires a ARM7 (and above) processor, I just buy > a board from somewhere like Olimex. > > > People often ask similar questions, and it generates a lot of answers, > > but without much feedback on what the "stopper" is. > > I understand. Below is my current thinking on the questions you ask. > > > Is it cost? Complexity? Availability? > > The breakout boards I see have a whole lot of extras added onto them > which are of no interest to me and just bump up the price and size. > > A number of them are also designed as standalone units instead of > something which can be plugged into a stripboard/veroboard base unit. > In that case, you have to work with what is on the board, instead of > been able to build your own circuit around it. > > Complexity is not a issue in that I can just ignore the parts of a board > I don't need. > > Availability is not really a issue; they tend to be freely available > here in the UK. > > When I get a idea for something, I like to be able to design something > which contains just the components I need, and nothing else. There's > also the fact that projects could involve more than one breakout board, > which rapidly starts multiplying the price difference. > > Therefore, this leaves the option which we have been discussing which is > having some bare generic adapter templates made which, when populated, > would contain nothing but the IC in question plus the 0.1 inch pitch > pinouts.
I would add to that a handful of decoupling capacitors---which will be more effective when not separated from the MCU power pins by the connectors and traces of the breakout board. You should also consider adding parts you know you'll need for most cases, like a crystal and, perhaps, resistors that set default boot behavior (boot0 and boot1 pins on the STM32 series).
> > The price of having custom boards made is not really too much of a issue > for me. For designing them, I would just use gEDA and the cost of a batch > of boards does not seem too bad (at least the last time I looked). > > The real problem with this, and this is the core problem here, is working > with components that small. I don't currently have the skill set required > for that and I am not sure what extra equipment is required in case I need > help soldering something that small in case my hands are not steady enough.
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.
> > > Unfamiliarity? Cost of tools? > > Cost of development tools for software development is not a problem. > For the hardware side of things, I just use a low cost JTAG tool for the > ARM boards (a Wiggler clone from Olimex) and I built a programmer for > the AVRs which I use with AVRdude. > > On the software side of things, both for AVR and ARM, I just use a open > source toolchain (gcc/binutils and, for the ARM boards, OpenOCD/gdb/ddd). > > I don't need any of the handholding stuff which you see in the commercial > toolchains. I just write my own headers (using the datasheet) if they are > not available or the manufacturer uses coding conventions I disagree with.
For some of the more complex ARM chips, the headers can run to several thousand lines. I usually start with the headers from the software provider and often replace some with my own definitions when I disagree with their style.
> > Likewise, on the ARM, I am now using my own startup code template, which I > alter based on the manufacturer's documentation and any issues raised by > the manufacturer supplied startup code (which I just view as documentation > for things which should have been in the datasheet/reference manual but > wasn't :-)). > > Unfamiliarity isn't really a major problem in a number of cases, but it > depends on the degree of unfamiliarity. Learning another ARM MCU isn't a > problem. Learning a completely new architecture (ie: MIPS) requires a > far larger amount of time to be available. > > Assuming I had the time on a specific project, I would take the lack of > familiarity as a opportunity to learn something new. > > > I have no real idea, which makes it hard to tailor future suggestions. > > > > One problem I see is that a lot of breakout boards are quad package, or > > dual row, which is not convenient for stripboards. Or they are DIP package, > > but have a lot of extras added, which bumps up the cost and forces you into > > specific design choices. I suspect what people really want, is just a chip > > on a DIP board, as cheaply as possible. There is little profit in that, and > > hundreds of possible chips, so it is unlikely to attract commercial interest. > > This is exactly the problem. I am quite capable of building my own circuits > provided the parts are in a size I can work with. I am not interested in > breakout boards that are loaded with a whole set of parts which bump up the > size and price. > > > BatchPCB makes it really easy for people to order bare boards, so that is > > half the job. > > The other half is finding an enterprising amateur willing to provide a > > soldering service for a few $. > > Thanks for the pointer. > > BTW, when I finally go down this route, it will be me doing the soldering > as I will regard it as another skill to be learnt. :-) > > I hope this helps you understand the issues I consider and the priority I > assign to each type of issue. >
Mark Borgerson
dp wrote:

> Oh, and for rework you will need two soldering irons, that is how > I do it at least. I also have a blower (hot air station, I believe), > but I have been getting away without having one in the past. > And I manage boards like this one more or less routinely: > > http://tgi-sci.com/misc/nmc3top.gif
The large IC on that board looks like a BGA package. I've been avoiding BGA for home projects because I can't figure out how I would possibly troubleshoot and rework such a board with exotic stuff like an X-ray inspection machine, etc. Have you got experience with BGA on a budget? Ed

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