Chipless "Pill Board" group buy?

I’ve got this idea that if we all band together and make a group purchase of some bulk quantity, we might be able to convince one of the “pill board” manufacturers to sell us a bunch of semi-bare boards without the stm32f103 installed. My thinking is that a board without the stm32f103c8 chip, but with the usb connector, voltage regulator, buttons, leds, caps, resistors, and XTAL components pre-soldered would appeal to most people on this forum. This empty board would make it easy to try out other stm32 series (stm32f0,stm32l1,stm32f3) if they have the same 48-pin pin outs. Pinout compatibility would need to be verified.

As far as manufacturers, I’m partial to the RobotDyn boards, although I’ve not purchased any. They seem to be well designed and constructed. Bonus is that the 1k5 pull-up is the correct value. Can anyone who has purchased a RobotDyn black pill comment?

Has anyone approached any manufacturer with this idea?

Is this something you would buy?

• What do you think is a fair price?
• How many might you buy?

Link to RobotDyn current product:

https://robotdyn.com/stm32f103-stm32-ar … dered.html

Group buy sounds great until the distribution to individual members is considered… we are a global group. International mailing and custom declarations is messy.

I like the black pill OK but it is $2.81 in 35 Qty. I suspect RobotDyn has them assembled rather than doing it themselves… but, maybe not since Adafruit bought a pick `n place machine for their boards. Buying w/o the uC might create issues for some members as not everyone is comfortable with drag-soldering a 48 pin package.

I personally think that the F4 board that was previously designed would be a better spring-board.

I must have 20+ blue boards around here… I’ve thought of using hot air to replace the uC but just never got around to ordering an F4 chip.

Ray

I didn’t see any lqfp48 stm32f4 or stm32l4.
Actually I found some you can buy : STM32F410CBT3, STM32L433CCT6

The target chip for me would probably be the STM32F373cct6 (256k/32k) 72MHz USB. Although it seems newark has a bunch of stm32f372 (not sure of the difference) for a $1.08 https://www.newark.com/stmicroelectroni … CMP=AFC-OP

I guess I should just order some chip-quik and one of those.

With my nearly non-existent SMD soldering skills, I think I would find it easier to solder on the new chip after removing the old one, as I can just reuse the solder that was left on the traces, rather than to solder the chip onto a clean board. (I converted one blue pill (actually with black PCB, but it was a blue pill in layout and errors) in this way. I had one solder bridge to fix afterwards, which I fixed with an x-acto knife.)

And removing the old chip isn’t that hard. (I used a guitar wire under the pins and an iron on top to pull them up one by one; that did damage one pad, but not fatally; if I were doing it again, I’d use advice I got from someone else on this forum to just cut the pins off by the package and desolder them one by one.)

Believe me, unsoldering an old SMD chip isn’t easier than just plugin a new one unless you own a desoldering station the guitar trick works 50/50

All you need for soldering SMD is soldering paste like this:
https://www.aliexpress.com/item/Solderi … 37395.html
Put a little thin film on the PCB and you can even solder it with a fine soldering iron – just google for it on YT. 48pin packages are no problem to solder by hand.

I am guessing that the pin cutting works every time, though.

How do you avoid bridges when you spread the paste between the pads? The one time I used paste, I carefully made sure it only went on the pads.

Just a simple answer: If you use only a thin film, don’t take care about!
There is no adhesion between the varnish and the flux. Here comes the problem: A PCB with a desoldered chip may be suffering from such adhesion.
Edit: Just buy some of the ultra cheap SMD (16 or 8 pin) adapters sold on ali
https://www.aliexpress.com/item/10pcs-S … 78033.html
and buy some useful cheap SMD chips (Audio DAC’s for example) for testing. This will raise your skills and you have plenty of useful DIN adapted chips at home. Best of all on the adapter is plenty space for some add ons like 100nf between GND and VCC or even one or two resistors.
Example: viewtopic.php?f=3&t=3416&p=43210&hilit=cs4334#p43177 (the little green one )

[arpruss – Wed Aug 29, 2018 7:44 pm] –
I am guessing that the pin cutting works every time, though.

Yes, if you don’t care about the original chip, this is by far the easiest method!

[arpruss – Wed Aug 29, 2018 7:44 pm] –
How do you avoid bridges when you spread the paste between the pads? The one time I used paste, I carefully made sure it only went on the pads.

Although the solder paste contains some, it is trivial to do drag soldering when using a flux pen and applying flux over the pads before soldering: the solder paste will then magically stick to the metal pins without any bridging.

But back top topic:
Another solution could be using http://dirtypcbs.com/store/pcbs
Once a layout is placed there anybody can buy copies of it. (10x10cm, 10 pieces – you can guess how many “bluepills” you can get out)
But: This is PCB only, without resistors and everything else.
So maybe asking RobotDyn about producing it or selling it without MCU? (I like all the RobotDyn things and spend the few bucks more for the “better ones”)
About the price: Even a <=2 EUR/USD blank bluepill is a superb price. Better 1.5 or so (but in 10pcs packs)

I have sent an email to robotdyn to see if this is something they would do. We will see what they say.

Personally, I’d prefer not to have to solder on all those little fiddly components. If I can’t get it pre-populated, I’ll just stick to pill boards and nucleo ones.

It doesn’t seem like people here are jumping up and down for this .. so maybe it is a waste of time.

With a hot air soldering station it is very easy to remove the chip and install a new 1. I use the hot air on about 300 degrees until the chip will just lift up with tweezers.

To solder new chip on I find 2 methods works well. Either use iron to load up the pads with solder then cool and put some flux on top of the built up solder and place chip on the pads the heat with hot air gun till the chip sinks down into the solder. Or second method is clean all old solder off and place a bit of solder paste on pad the place chip and heat with hot air gun.

[Rick Kimball – Wed Aug 29, 2018 8:51 pm] –
It doesn’t seem like people here are jumping up and down for this .. so maybe it is a waste of time.

I don’t think that….but “we” are calculating
For me I’m referring to the STM32F410CBT3: 100MHZ, 3x SPI (2x I2S) sounds more than interesting, but you wont get it on ali and I didn’t found a local seller for private buyers (Europe) except Mouser: For about 10 pcs the price is about 3.58, so with VAT and shipping costs up to 5-6EUR/unit plus naked board. This is nearly the price for the Black STM32F407VET board, but for sure: much smaller form factor.
Pitty, with 64pin we would have much more choices…

I’m pretty sure you can get free shipping from arrow even if international.

https://www.arrow.com/en/products/stm32 … lectronics

For me that is free overnight shipping with qty 1 pricing of ~$5 Not bad for 256k flash/ 64k ram.

Or this for ~$4
https://www.arrow.com/en/products/stm32 … lectronics

Or this for ~$3
https://www.arrow.com/en/products/stm32 … lectronics

Now I need to see about pin compatibility. It seems like I can just drop it in.

“AN4649 Application note – Migrating from STM32F1 Series to STM32L4 Series / STM32L4+ Series microntrollers”

https://www.st.com/content/ccc/resource … 156964.pdf

arrow: “No Stock Available” for the F4 :/
But mouser is free shipping for over 50 EUR, not sooo bad.
About pin comp.: We must take care about the layout: If the chip supports 3 SPI for example, maybe not all pins are routed to the blue pill board.

So I heard back from the robotdyn people:

robotdyn.com wrote:“Hi Rick,

I think that’s possible. How many do you need?

Would you be interested if we deliver this board with your version of
the chip already soldered in?

What chip do you want to use, BTW?”

I’ve had some more interaction with the robotdyn people. Their response answers some of the questions we’ve been wondering:

robotdyn.com wrote:I’m happy to hear you enjoy our products!

Thanks for the link. As I understand, you’re considering several
different options – including a complete new board.

I see a number of ways how we could assist:
– Provide the board without the chip, as you initially requested
– Design a new board for you – the way you want it, with or without
the chip. This may be expensive, since we’ll have to charge you for
the relevant design and development work
– If you or someone else from your community will design the right
board – we can make a special batch for you. This is usually feasible
for batches of at least 200-300 pcs, but if the design is easy enough
– we could probably run a smaller one.

I’m sure we will be able to make it cheaper than getting a PCB at
OSHpark and components at a local store!

Wow, the Robodyn people are sounding really nice

[madias – Thu Aug 30, 2018 6:11 pm] –
Wow, the Robodyn people are sounding really nice

We do nice products, too!

Hi All,

Thanks a lot for inviting me here!
To keep it on-topic, I would confirm what Rick has posted already. There’s even more: we may offer special versions of our “Black Pill” with the MCUs of your choice (so you won’t have to practice your fine soldering skills). At the moment this is just an idea, not a commitment. To start looking into it, I need to understand which MCUs will be demanded and the approximate quantities.

On the other hand, does the ‘Black Pill’ suit most of your requirements? Or should we come up with something totally different and, perhaps, more flexible? I’m open to your ideas!

As for the group buy… I’m discussing this within my company, and we’re trying to find a way to offer individual shipping to every participant. So that there will be no need for someone to place a combined order and take care of further distribution. I think we have some progress already!

May I make a suggestion.

Since many people consider price, maybe it is possible to look a second board that can be sold world wide that will sell in high quantities. Maybe it can be called the black pill Plus with maybe a top of the line STM32L4 chip instead. This would make for little retooling or redesign just a change of MCU. Considering the popularity of the Blue/Black Pill it would have a readability high chance of quantity world wide sales.

Maybe we can have a vote on what MCU people think will make the best black Pill Plus and most popular choice could be put into production. Some considerations might be price/performance

[andrewju – Thu Aug 30, 2018 10:59 pm] –
Thanks a lot for inviting me here!
To keep it on-topic, I would confirm what Rick has posted already. There’s even more: we may offer special versions of our “Black Pill” with the MCUs of your choice (so you won’t have to practice your fine soldering skills). At the moment this is just an idea, not a commitment. To start looking into it, I need to understand which MCUs will be demanded and the approximate quantities.

Personally, I am fond of the STM32F303CxT6, because of the high speed ADC (up to 18msp). But I am not sure I have that many projects for them.

On the other hand, does the ‘Black Pill’ suit most of your requirements? Or should we come up with something totally different and, perhaps, more flexible? I’m open to your ideas!

Personally, I like the Black Pill form factor a lot, assuming that the USB pullup resistors are good and there are both 5V and 3.3V pins.

To keep in mind, what are the 2-3 things we love most about the Blue/Black Pill:
For me: price + form factor + Rogers Core
After reading all post, I totally prefer two things:
1. A blank Blue Pill with corrected resistors – this would be easy to produce and a 48pin chip isn’t hard to solder even for novice people.
2. The Community board as a “missing link” on the available dev boards. But: It’s all about the price it must set <=10USD/EUR otherwise it’s a “special device” for “special people” (ok, maybe we are all special) but makes no sense for the distributor. Downside: This would be a frontal attack against the teensy 3.5/3.6

I made a board with a bluepill compatible pinout, you can get it from

https://drive.google.com/open?id=1wGwwu … 6fntMrBHum

It is somewhat longer than the original, but otherwise fits in the same socket, and uses all through-hole parts except for the chip itself. It works fine and seems to have somewhat lower RFI and susceptibility than the original bluepill.

Dan

Here’s the picture I posted in the other thread.

Why do you keep using bulky through-hole components when you are able to solder a fine pitch LQFP48 package?

Well I can solder surface mount, but frankly I don’t like it very much. I guess I consider it something that I have to do for work, but when I do my own thing, I like to have something I can see without a magnifying glass. I know its bigger and bulkier and I have to clip leads, but I am not the most agile person. Having the through-hole parts around is just easier for prototyping unless its something that requires being small like for RF/microwave work. I just like keeping things simple as possible. I may be a reactionary and a Luddite, but I was born at this scale, and not a lilliputian.

Dan

What is weird is the mix between SMT and TH devices.

I personally stopped using TH components for prototyping 15 years ago except for breaboards, And yes it requires a magnifying glass but it is sooooo much easier once you get used to it. 0805 and 0603 are easy to solder, unless you have some vision problems. At work I mount 0402 or 0201 components routinely with a good Mantis magnifying glass but I need to restrict drinking coffee beforehand. And for small prototype runs, I use a stencil and a cheap T962 IR reflow oven instead.

With my (nearly) 44 years, I’m going to suffer from presbyopia, combined with my “regular” myopia. Even with my brand new varifocals I need to take away the glasses for near field things. But I’ll never go back to TH if it’s possible, because the timing factor is relevant: How long do I need for a real little project example: 3-4 IC’s, 20 resistors, 15 caps on TH (cutting wires and searching for cold soldered points included) compared to SMD? I do it with a thin regular soldering iron, nothing special (ok, I use soldering paste instead of s. wire). I refused SMD a long time for nothing Beside that, all of my favorite chips are SMD only (or extrem expensive in TH) and the “birdseed” (resistors,caps) 0805/0605 are really no problem with a little experience.
Ok: For a “first timer” student project, who have never held a soldering iron in their hands, I wouldn’t recommend starting with SMD:

(This was really an advertising by the German Craft Association, translated text: “We are craftsmen we can do that”. Maybe the maxim about German craftsmen is they all have a supernatural skin, but that does not explain why this person wants to maltreat a fan with a soldering iron)

For all my small surface mount components I solder with hot air gun on the lowest air speed setting. I melts all the solder for all the pads so that the small component will then move and settle in right place. Fpr components as large as 0805 I will apply paste with syringe but for small components I will cut a stencil out of 5mil or 7mil mylar with a laser cutter.

If your a maker I definitely suggest investing in a cheap laser cutter as I use mine for so many different purposes especially as it cuts acrylic like butter which is easy to bend and glue into what shapes you want but about 1 millions times faster than 3d printer

I did start with using tweezers to place components but it got way easier and faster when I got a vacuum pump.

see here a stencil I laser cut from mylar for a CP2104 chip in QFN-24 package

20000317_133017.JPG (19.43 KiB) Viewed 278 times

You’re all probably right I should just go SMD. I am far-sighted with +3-4 diopters vision, which is unusual, and so I find it hard to see close up with a magnifying glass, even though I already wear +1.5 D bifocals. It’s probably more vision than anything else really, sometimes I really strain my eyes with some of these parts. I grew up with through-hole in the early 80s (think Apple IIs and 8-bit computers such) and never really got out of the habit, and have always had far-sighted vision.

I use the “ugly” method of soldering the LQFP 48 parts. Basically use a flux pen on the board, solder two opposite pins on, drag solder over the pins, and then sop up any solder bridges with braid. Not the best, but it works. At least the STM32F103 is only 0.25 pitch and not smaller even. I don’t use stencils and paste or anything like that for my personal projects, and usually use professional surfaces if I have a board with a lot of small SMD parts (0402/0603).

But hopefully some of you can find use of my through-hole dev board. I am using it for a ham radio project and wanted a version of the Bluepill that I had the schematics/details/board layout on so if something went wrong I would not be wondering if it was due to the Bluepill or something else, but I tried to make it compatible so if others use the projects I design with the Bluepill they could just buy the $2 version if they choose. It only took me a few hours to lay out and takes only 20-30 minutes to assemble at most. Before I started to use the Bluepill I looked at several alternatives and really liked that the stm32duino libraries and bootloader are open source, that is very helpful to me, because a lot of commercial alternatives have hidden parts.

Dan

I am also old enough to suffer from presbyopia, combined with my old myopia, but with a good magnifying glass, it is not a problem.

I also grew up with the Apple ][ in the early 80’s (80-81), and I developed my first PCB for a 20 mA current-loop add-on card based on an MOS 6551 ACIA and optocouplers to drive an old Teletype Model 33 KSR from 1963 as a printer.

Don’t consider drag soldering as “ugly”: this is just a normal method, at least not uglier than wave soldering.

The minimum setup is an hot air gun and a good magnifier glass and have your stencil cut where you print your PCBs.

Then if your projects are getting bigger or more frequent, invest into a small laser cutter, then replace the hot air gun with a 200€ IR reflow oven, and use a vacuum pump for component pick & place. Given the expensive price you pay for prototype PCBA, the ROI is only a few prototypes.

A quick update:

Following up on the initial request, If there is a demand, we are able to run a special batch of the “Black pill” board – without the MCU.

For the reference, our board already includes the correct USB pull-up resistors, a 5V / 3.3V pins, and it comes with the high-quality crystals (including the one for clocks). Even if some of these features are overkill for certain projects, it’s nice to have anyway! The chipless version will maintain all of these, of course.

The estimated price of the chipless version is expected to be $2.59 (USD) per piece, excluding shipping. To make things easy, I suggest that we publish this special version as a product on www.robotdyn.com. This way everyone will be free to place their orders and choose a suitable shipping option. Of course, we are ready to do a ‘centralized shipping’ in case someone wants to take care of further distribution.

I suspect the chipless boards won’t sell well to general public. So this is something we will do primarily for this community. My major concern is that we can’t afford to produce these boards on demand in little quantities. Therefore, if this entire story goes further, I will need to know an approximate number of boards we need to put to our production plan in order to have just one batch of these.

BTW, we can also supply MCUs of your choice in quantities of 5pcs and up (they will be NOT soldered, otherwise our internal processing will get too complicated).

As for the F4 version, we’re working on preliminary costs estimation based on a 4-layer PCB.
I’ll post an update when I get more news.

OK, thank you for the update!

Thanks andrew for the quick followup.

[andrewju – Mon Sep 03, 2018 2:30 pm] –
The estimated price of the chipless version is expected to be $2.59 (USD) per piece, excluding shipping. To make things easy, I suggest that we publish this special version as a product on www.robotdyn.com. This way everyone will be free to place their orders and choose a suitable shipping option. Of course, we are ready to do a ‘centralized shipping’ in case someone wants to take care of further distribution.

… Therefore, if this entire story goes further, I will need to know an approximate number of boards we need to put to our production plan in order to have just one batch of these.

What is the number of boards you need to sell to even bother doing this? I’m all for just ordering from the website if that is possible.
If people post the number of boards they would buy, I’ll consolidate on this message.

• Name/Nick- Number of boards
• Rick Kimball 10

I’m not sure if this is an option…

But I know RobotDyn has / had a AliExpress store, and I recall that a while ago another company allowed pre-ordering of ESP32 boards, with a long lead time.

I’m not sure if RobotDyn needs to pay commission on an order even if they cancel because of lack of demand…

But if there is no cost to them if they don’t deliver and AliExpress give the customer their money back…

They potentially AliExpress could be used as the escrow system.

I’m sure AliExpress change commission, so the price would be higher using this system, as the cost of the board would be fairly low, perhaps the additional cost (probably 20c per board) may be worth it.

PS.

I’m not skilled enough to solder SMD chips, so I”m not interested in the chipless board, but I am interested in the F4 Pill board, if RobotDyn can get a competitive price.

[RogerClark – Tue Sep 04, 2018 7:00 am] –
I’m not skilled enough to solder SMD chips, so I”m not interested in the chipless board, but I am interested in the F4 Pill board, if RobotDyn can get a competitive price.

Same for me.
The news about an eventually competitive F4 board can be spread on hackaday, so the buyer can get his business.

[RogerClark – Tue Sep 04, 2018 7:00 am] –
I’m not skilled enough to solder SMD chips, so I”m not interested in the chipless board, but I am interested in the F4 Pill board, if RobotDyn can get a competitive price.

+1

Currently only reasonable small factor F4 board is the blue “mini” stm32f407vet6 which is around 9-10$ on ebay. And that is double the size of a Blue Pill

[Rick Kimball – Mon Sep 03, 2018 4:26 pm] –
What is the number of boards you need to sell to even bother doing this? I’m all for just ordering from the website if that is possible.

I would say it doesn’t make much sense to run a batch of less than 50pcs.
But we’ll see what we could do based on the actual numbers.

Sadly, this idea doesn’t have as much support as I thought it might.

[Rick Kimball – Tue Sep 04, 2018 2:26 pm] –
Sadly, this idea doesn’t have as much support as I thought it might.

Have at least a *bit* of patience, and you may have revived the F4 pill board, so good result anyway XD.
For me i’m already drowning in pill boards, and can easily remove the mcu myself using my hot air station. So i have no need. (i also remember from my chip swap experimenting days, that the blackpill has some smd caps/resistors pretty close to the chip, so making it hard to manipulate with the hot air station >_<.
I stuck to the regular bluepill, nothing too close to the chip, and good pads that also supported the QFN packages.

[racemaniac – Tue Sep 04, 2018 3:06 pm] – i also remember from my chip swap experimenting days, that the blackpill has some smd caps/resistors pretty close to the chip, so making it hard to manipulate with the hot air station >_<.
I stuck to the regular bluepill, nothing too close to the chip, and good pads that also supported the QFN packages.

You can use a mask made from copper tape around the chip to remove, this will prevent the small SMD caps/resistors to fly away. Then hold the chip with tweezers and heat until the PCB falls.

… And regarding the chipless BluePill, I can remove the original STM32F103C8T6 myself, so I don’t need them.

I am more interested if RobotDyn can actually manufacture and distribute the F4 BluePill with an LQFP64 package and all the extra options we added.

If the f4 blue pill was a reasonable price I would also buy 1 as it would be a considerable step up capabilities than the stm32103 in a similar factor and definitely worth a little extra in price. I also believe that once the world wide maker community discovered it, it would sell well.

Well it appears I’m the only one interested in a chipless pill board. I’m not going to pursue this any more. I’ll eventually buy a hot air station or some chipquik.

As far as the F4 community board discussion, I’m going to split those posts off into a separate thread so whoever is interested in that can continue discussing. Here is that split: viewtopic.php?f=3&t=4086