Haven’t kept up where our F4 bluepill is (i know some people were actively testing them/using them), if we can fix its issues, it would be a very interesting candidate to have produced by them (with or without MCU, both are interesting).
But you would need to ask @squonk43 etc first , as the chances are it would get cloned and they may get no credit for their work.
(I don’t mean financial credit)
At the risk of loosing a few dollars, perhaps RobotDyn could list the F4 Pill board and if they get enough confirmed orders, they make them ..
I.e a bit like Kickstarter but without the middle man , I.e without Kickstarter themselves
We do have plans to expand our STM32 products lineup, although there’s no specific roadmap for that (yet).
If there is a demand, we’ll certainly focus to bring up a solution ASAP.
[andrewju – Fri Aug 31, 2018 10:51 pm] –
May I ask what is the story with the F4 ?We do have plans to expand our STM32 products lineup, although there’s no specific roadmap for that (yet).
If there is a demand, we’ll certainly focus to bring up a solution ASAP.
Basically, the small formfactor of the “pill boards” is really nice (and usually affordable), but we found the 48 pin STM32’s on it a bit limiting, so we made a prototype of a board with a 64 pin STM32F4 on it, same pinout as the smaller boards, and the unused pins are mostly broken out with surface pads and/or used for an sd card slot on the board (which is also a really nice to have) (and lots of other features: usb host mode, can provide usb power, rgb led, separate LDO for the ADC’s, …).
For most of our projects, arduino uno (/similar) sized boards are just big, annoying, impractical, so something more powerful with a 64 pin stm32 would be awesome.
Here you can see what we were working on. We’ve got a mostly working prototype. (it’s quite a big thread ^^’ , but i linked a post in it showing a rendering of the pcb).
Not sure how well we represent your customer base, but something similar to that could really sell well .
Yes, manufacturing and distributing our community-designed STM32 BluePill F4 board by RoboDyn may be an idea.
First of all, let me apologize for stopping the development of this board some months ago, I had personal issues, including some serious health problems, so I could not allocate time to work on this. I may work back on this today, but I will certainly need some help from other users here.
Second, despite the fact that I personally draw the schematics and did the board layout, I consider this work as an www.stm32duino.com community work, as many users contributed to this design either by bringing some ideas or actually testing the board. This is why I attributed the copyright to www.stm32duino.com. But even if we get the copyright, this design is using a CC-BY-SA 4.0 license, allowing anyone to use, modify, distribute, make money of it with the only obligation to keep the original copyright notice. This includes of course companies like RoboDyn to manufacture and sell it without further restriction and without any royalties to pay.
All the design files are available on Github, they are comaptible with Kicad v5 stable:
https://github.com/rogerclarkmelbourne/ … r/Squonk42
The forum thread is here but beware, it is 84 pages long!
In order to save you browsing all this information, here are some shortcuts:
3D rendering of the STM32 BluePill F4 board:
Here are pictures of the actual bare PCB:
Schematics in PDF:
https://github.com/rogerclarkmelbourne/ … ematic.pdf
Layout in PDF:
https://github.com/rogerclarkmelbourne/ … Layout.pdf
BOM in CSV format:
https://github.com/rogerclarkmelbourne/ … PillF4.csv
There are still a few issues with this board, but nothing serious that can survive a good debugging session. At least these documents above should be enough to help RoboDyn to evaluate the cost of manufacturing and distribution of this board and estimate a retail price.
Although it is more complex and contains more components than the original BluePill STM32F103C8T6 board, it is pin to pin compatible but uses a more powerful STM32F4 or STM32F7 CPU, has built in SDCard slot, USB OTG with OV/OC protection, RGB LED, user button, separate analog LDO and LiPo battery charger. Components have been carefully selected to be easily sourced.
If RoboDyn is interested, this should motivate some of us to finish debugging this board asap, provided the retail price is reasonable.
.
This may also be an opportunity to have a unique board featuring one of the new cheap and powerful STM32F7x0 “Value Line” CPUs, like the STM32F730R8 with an LQFP64 package which is compatible with the STM32F722xx?
In single QTY, the STM32F730R8 is cheaper ($4.96) than the STM32F103C8T6 ($6.06) at Digi-Key 
But they are 216MHz vs. 72MHz CPUs with additional 8kB/8kB I/D-cache, single precision FPU, DSP and MPU, 256KB vs. 20KB of SRAM, operation down to 1.7V and low power modes, 1 more ADC and also faster, 2 DACs and 18 timers vs. 7 
Also 1 more I2C, 1 more UART/USART, 3 more and faster SPI some with Quad-SPI and/or I2S, serial audio interface, USB OTG, AES block and 2 SD/MMC!
It seems the only required change to our STM32 BluePill F4 board is to move the VCAP_1 one pin left to PB11, which can probably be a simple BOM option.
But this would require at least one Arduino core to support the STM32F7x0.
[Squonk42 – Sat Sep 01, 2018 12:38 pm] –
But this would require at least one Arduino core to support the STM32F7x0.
…as not as a one man show, to be a little bit ironic (generic core, “official” core).
I would love to get some for my hobby projects, aside from my affiliation with RobotDyn.
I’ll ask our engineers to evaluate the production costs, and I think we’ll move forward with this.
I think it’s better to move this part of the conversation to the board thread, or … ?
As for the original question regarding the “chipless” board, I shall be able to come up with a few offers early next week.
[andrewju – Sat Sep 01, 2018 12:59 pm] –
Wow, the F4/F7 “Pill Board” is really nice!
I would love to get some for my hobby projects, aside from my affiliation with RobotDyn.
I’ll ask our engineers to evaluate the production costs, and I think we’ll move forward with this.
I think it’s better to move this part of the conversation to the board thread, or … ?As for the original question regarding the “chipless” board, I shall be able to come up with a few offers early next week.
Yup, reviving the original thread for this is a good idea .
And keep in mind the current board is a first beta, it has some small known issues, and things like ADC noise haven’t been tested yet (and it has optional components etc…) it’s not a finished product yet ^^’
[Squonk42 – Sat Sep 01, 2018 12:38 pm] –
<•••>
But they are 216MHz vs. 72MHz CPUs with additional 8kB/8kB I/D-cache, single precision FPU, DSP and MPU, 256KB vs. 20KB of SRAM, operation down to 1.7V and low power modes, 1 more ADC and also faster, 2 DACs and 18 timers vs. 7
<•••>
Higher frequency clock, advanced A/D … this screams for a 4 layer board w/ analog & digital ground planes. You can bypass everything, but only the separate ground planes will squelch by lowering the noise floor.
Everyone knows that 4-layer boards are more expensive, but RobotDyn may have suppliers that can manage such a design for a small incremental cost.
Ray
1) the ‘chipless pill board’ which is intended so that stm32 f0 / f1 / f3 can be swapped for each other
2) an f7 ‘value line’ based board
for both one of the ways might literally be similar to this
https://item.taobao.com/item.htm?spm=a1 … 6561036331
https://item.taobao.com/item.htm?spm=a1 … 2494079527
for (2) an f7 based board i’d think would probably suit different use cases
as cortex-m7 is a super scalar processor it would better suit an environment with large amounts of ram, it could be sdram for that matter
possibly in the megabytes.
the built-in flash can then work more like bios as an ‘os loader’ and perhaps even being the os itself
then programs can be loaded from say an sd card and run in *ram*
this is dramatically different from the ‘mcu’ use case and it sits between the ‘arduino’ land and the ‘Rpi’ land.
the only shortfall being that cortex-m7 – stm32 f7 do not have a mmu
it would in fact fall into the category that is in the ‘uclinux’ domain
http://www.uclinux.org/
stm32f7 with additional ram (be it sdram or sram) and sd card is indeed a ‘missing product’, it fills the void between ‘arduino’ and ‘RPi’
it sits in the middle land where the ipaq / windows mobile / windows phone and various earlier ‘personal digital assistants’ and windows mobile phones used to thrive
the difference? stm32 f7 has all the capabilities for additional connectivity and i/o (SPI , I2C, ADC, DAC etc) where all those ‘personal digital assistants’ don’t do as PDAs are aimed at a different crowd
i’d think stm32f7 would fill a niche similar to this:
Ok, I will revive the old thread
Probably create some issues in the Github repo too, so it will be easier to track independent problems than in a 80-page long thread with interleaved subjects.
@mrburnette: yes you are right, maybe RobotDyn can tell us what will be the cost difference between 2-layer and 4-layer for this board? If 4-layer is not much more expensive, then I can turn the current design to use separate ground planes and power planes?
@ag123: yes there are 2 themes, I will move the 2) back to its old thread, but this may also be the same board without the CPU, as an LQFP64 footprint provides a much broader choice than LQFP48.
I think the STM32F7 is only good as an MCU on steroids if you need real-time control with complex math (FFT, matrices, PID…) with tons of interfaces. Drones and 3D printers are a good target market for these.
Adding more RAM/Flash will increase the bill drastically, and then you will hit the RPi Zero / NanoPi $5-$10 sales point and there is not much room to make money here IMHO, as the silicium cost for MCU or CPU is almost the same.
If I need both a capable CPU with Wi-Fi/BT/Ethernet/USB connectivity and tons of RAM/Flash I will use an RPi-class board, and if I need many GPIOs and/or interfaces, I will add a capable MCU driven over I2C or SPI to handle real-time operations. In some situations, a single ESP8266 or ESP32 may also be a good solution, although GPIOs/interfaces are quite limited in these.
[Squonk42 – Sat Sep 01, 2018 5:42 pm] –
maybe RobotDyn can tell us what will be the cost difference between 2-layer and 4-layer for this board? If 4-layer is not much more expensive, then I can turn the current design to use separate ground planes and power planes?
Given the size of the board, the difference between a 2-layer and a 4-layer PCB should be less than $1, probably even within $0.50 (USD).
I didn’t analyze the BOM yet, so I can’t estimate the final price at the moment.
RPi don’t offer sufficient IO interfacing opportunities, most of the time one is left with usb as an interfacing option.
Beagle bone black does that, but the STM32 F4, F7 families has much faster ADCs, DACs and has a 12 bits precision etc
the stm32f7 discovery board from ST perfectly match that use case
https://www.st.com/en/evaluation-tools/ … overy.html
ST even place an arduino header there, but they could have better simply pull out more pins to ordinary headers which would offer more interfacing opportunities
uCLinux is a full blown OS as compared to bare metal programming or even for that matter compared with RTOS
Thus it will actually depend on the total price.
As a 32F411DISCOVERY board from ST featuring an STM32F411VET6, an ST-LINKV2, an L3GD20 3-axis motion sensor, an LSM303DLHC 3-axis accelerometer, an MP45DT02 microphone and a CS43L22 audio DAC with integrated class D speaker driver and 8 LEDs is only $15 @ Digi-Key, I hope we will be able to keep the BluPill F4 between $5 and $10, depending on the CPU and options.
Let’s see if we can reach this target together!
[ag123 – Sat Sep 01, 2018 7:44 pm] – the stm32f7 discovery board from ST perfectly match that use case
https://www.st.com/en/evaluation-tools/ … overy.html
I used uCLinux over 10 years ago while it was still not part of the main kernel, so I know its pros and cons. Among the latest, I should point out the total lack of isolation between processes (causing a machine crash if one process is gardening the memory), and the inability to do a fork() without exec() (causing headaches when porting any package to uCLinux), both due to the lack of MMU.
For the price of this STM32F746G-DISCO board ($56.25), I can easily get a RPi Zero W with a screen running a full blown and more capable Linux, plus a small SMT32F7 board to handle real-time peripherals over I2C or SPI, depending on required speed 
I’d guess that’s a reason given that the price between say a M7 break even with a Cortex A. Cortex-A is still a preferred platform to run mainstream linux given the MMU advantage alone.
As for Cortex-M, it would need its own operating system and currently uCLinux is one of them that runs on it, but i’d consider uCLinux a ‘work in progress’ project.
running multiple apps concurrently on Cortex-M is distinctly different from running in an environment with a MMU, the memory address is shared and real as compared to virtual memory and apps that’s not properly written and made completely relocatable would cause the app and even the os to crash
Another lighter alternative to have a multitasking OS on even smaller Cortex-M CPUs is Nuttx, discussed in this thread:
viewtopic.php?f=45&t=2553
IMHO its a bit too soon to jump to an F7.
Re: 4 layer board.
They always seem around 3 times the price of 2 layer, but I guess in this case that’s not a huge amount of money.
But it’s all to easy to keep increasing the spec until the board ends up costing too much for the mass market
[RogerClark – Sun Sep 02, 2018 8:01 am] –
I think perhaps the F4 is the best option at the moment, the LibMaple code has some F4 support the STM F4 Core is fairly mature, and I think STM32 GENERIC has an F4 variant
IMHO its a bit too soon to jump to an F7.
GenericCore supports F4 for sure (I’m using it with my STM32F407VET “black” board) but: Daniel may have lost interest in further development or is busy since an half an year (only a handful updates since them). The “official” core is far beyond usability at the moment and the F4 libmaple is beyond the F1 core and a one street way (in further looking to F7). Maybe a cheap F4 bluepill board will raise the interest of many members here, but I strongly recommend that one of the 3 cores should be chosen by all members for further investigation. Maybe it would be a wise decision to go with the “official” core because of future updates by ST (I hope so). So it would be an easier step to go with the F7 in a few years.
BTW: The STM32F407VET “black” board is under 8 USD at the moment and has some really nice goodies (SDIO SD card slot, SPI Flash EEPROM)
Do you have a link for this STM32F407VET “black” board @ 8 USD, please?
I am not objective of course, but the 407 VET is much larger and not compatible with the BluePill and single breadboard, and it does not feature a battery charger or RGB LED 
Sorry, starting US $8.95 (My mistake, cause 1:1 EUR to USD isn’t a good idea anymore (since when?) I stroked EEPROM in my post before, cause it’s really SPI Flash. I’m talking about this one:
https://wiki.stm32duino.com/index.php?t … T6_Variant
This is well known and documented.
For sure they aren’t comparable with the blue pill size factor and I’m using them for bigger – not battery powered – projects. This might be also a good question: F4 compared to F1 in relation to power consumption (incl. sleep / deep sleep…) in a “real” environment (so not on the datasheet only).
Still not expensive- though. Thiis gives us a challenging highest price tag for the Bluepill F4 board.
9.66 USD free shipping. (ok, your location is France, so shipping might be the same as here in Austria, but we are nice people and doing price lists in USD
)But for some reasons the STM32F407xx are really cheap in china, even if you buy a single chip, but a ***VET or ***ZET chip is not what we want for a small device (I think 64 pins is ideal)
So I would say: This board is the reference for the “big board class” with extra features (but not suitable for every project)
The community board is “special need”, not the 100000+ produced devices like the blue pill.
So, being realistic, I would say:
~10-12 USD: I’ll buy it. (realistic/optimistic price, above that: Hello Teensy )
~6-8 USD: This maybe could be a new “standard board” (if they’ll produce 1000-10000+)
But: Keep in mind, what I said about choosing the core
(I’m going to do (and publishing) some codes (not libraries, cause I hate libraries) for *HAL, like I2S in near future , but really “generic” and not for “genericCore” or “STMcore”)[stevestrong – Thu Sep 06, 2018 3:37 pm] –
I would buy at least 10 pieces of bluepill-type F4 board, if the price is reasonable (~5 EUR).
i would expect closer to 10€ (assuming it’s with all the bells & whistles), which i would still find great value if you compare it to a regular bluepill, and @ 10€ i’d buy 10
but when making this, it’ll probably make a lot of sense to also see if a budget version isn’t feasible. usb host, lipo charging, … it’s all very fancy, but who really needs it on every board. a basic version with just decent adc, powerful microcontroller, sd card & usb slave as close as possible to 5€ would also be awesome.
https://www.st.com/en/microcontrollers/stm32f405rg.html
they are apparently the smaller ones in the stm32f405 – stm32f407 families
boards featuring them today are the ‘micropython’ boards
https://store.micropython.org/product/PYBv1.1
as well as offerings from olimex
https://www.olimex.com/Products/ARM/ST/STM32-H405/
one of those things is that stm32f405 is a LQFP64 chip, which means that there are probably quite a bit more interfacing pins vs the stm32f103c{8,b} blue pill / maple mini / black pill etc which is a LQFP48
it may hence mean that if we stick with blue pill / maple mini type form factor, we may not be able to put all the pins in a single row and 2 rows of pins (dual header) on each side may be needed for that, otherwise the board would probably need to be pretty ‘long’
there is once a thread about ‘tiny’ f4 form factor boards, it may be interesting to review them
viewtopic.php?f=39&t=1977
one of those things noted about tiny f4 boards is that some of those boards are drone controllers and that those drone controller boards don’t pull all the pins out to the headers which cripples the use of those boards for general purposes.
and among the better ones are the 2 boards above i.e. the micropython board and the other one from olimex which pull the pins out to the headers enabling it to be used as a more general f405 board
in the smaller quantities, i’d think the costs would be similar to the micropython and olimex boards, it probably won’t be the ‘cheap’ blue pill / maple mini type of costs. but nevertheless some of the ‘wins’ of stm32f405rg vs stm32f103c{8,b} are:
– it has 2 DAC in it, stm32f103c{8,b} doesn’t have that
– 1 m flash (for RG)
– 192(112+16+64) k sram, 4 k backup s ram – total 196k sram > blue pill / maple mini ~ 20k
– 3 x SPI (2 of them I2S)
some users may be drooling over the sram context, it enables use cases that is impossible on bp / mm (e.g. micropython and likely many more)
malloc would make sense on those boards
today that substitute is to use the lower cost stm32f407ve * boards for those purposes, they are covered in the ‘tiny’ f4 thread as well.
the ve* has the additional benefit of having things like fsmc, a lot more interfacing pins etc
but as a result it ve and other boards are bigger
[ag123 – Fri Sep 07, 2018 7:14 am] –
among the smaller form factor chips, i think one of them is the stm32f405rg
https://www.st.com/en/microcontrollers/stm32f405rg.html
they are apparently the smaller ones in the stm32f405 – stm32f407 families
Yes, this is the chip we chose for the BluePill F4 for this reason. Until the newest STM32F730 “Value Line”, this was the best bang for the buck.
[ag123 – Fri Sep 07, 2018 7:14 am] –
boards featuring them today are the ‘micropython’ boards
https://store.micropython.org/product/PYBv1.1
as well as offerings from olimex
https://www.olimex.com/Products/ARM/ST/STM32-H405/
Both of these boards are not breadboard-friendly and the MicroPython one is particularly overpriced.
[ag123 – Fri Sep 07, 2018 7:14 am] –
one of those things is that stm32f405 is a LQFP64 chip, which means that there are probably quite a bit more interfacing pins vs the stm32f103c{8,b} blue pill / maple mini / black pill etc which is a LQFP48
it may hence mean that if we stick with blue pill / maple mini type form factor, we may not be able to put all the pins in a single row and 2 rows of pins (dual header) on each side may be needed for that, otherwise the board would probably need to be pretty ‘long’
No, actually only a few pins are added connected to port C. Out of them, PC8-12 are used for SDIO, thus only PC0-7 are not present on the LQFP48 package. The BluePill F4 uses PC8-12 for the built-in SD Card, and PC0 for controlling the USB VBUS switch. PC1-7 are exposed as soldering pads with a 1.27 mm pitch on the bottom side. Besides their standard GPIO function, their only interesting function would be for exposing the I2S interface.
[ag123 – Fri Sep 07, 2018 7:14 am] –
there is once a thread about ‘tiny’ f4 form factor boards, it may be interesting to review them
viewtopic.php?f=39&t=1977
one of those things noted about tiny f4 boards is that some of those boards are drone controllers and that those drone controller boards don’t pull all the pins out to the headers which cripples the use of those boards for general purposes.
and among the better ones are the 2 boards above i.e. the micropython board and the other one from olimex which pull the pins out to the headers enabling it to be used as a more general f405 boardin the smaller quantities, i’d think the costs would be similar to the micropython and olimex boards, it probably won’t be the ‘cheap’ blue pill / maple mini type of costs. but nevertheless some of the ‘wins’ of stm32f405rg vs stm32f103c{8,b} are:
– it has 2 DAC in it, stm32f103c{8,b} doesn’t have that
– 1 m flash (for RG)
– 192(112+16+64) k sram, 4 k backup s ram – total 196k sram > blue pill / maple mini ~ 20k
– 3 x SPI (2 of them I2S)some users may be drooling over the sram context, it enables use cases that is impossible on bp / mm (e.g. micropython and likely many more)
malloc would make sense on those boards
today that substitute is to use the lower cost stm32f407ve * boards for those purposes, they are covered in the ‘tiny’ f4 thread as well.
the ve* has the additional benefit of having things like fsmc, a lot more interfacing pins etc
but as a result it ve and other boards are bigger
The drone controllers are not interesting as they are too dedicated to this usage and don’t expose much of the pins. The remaining ones have all strange form-factors that are not breadboard-friendly: some of them have dual-row headers, some in a “U” shape, most of them are just too wide to use on a breadboard.
This is where our BluePill F4 with STM32F405RGT6 at a reasonable price with a BluePill STM32F103C8T6 pinout could be interesting, provided that the price is good. I agree with the ranges from @madias: ~6-8 USD would make it the new standard board, and ~10-12 USD would be a bit too expensive, but still below all existing general-purpose F405 boards, with a nice form-factor.
[racemaniac – Fri Sep 07, 2018 6:37 am] –[stevestrong – Thu Sep 06, 2018 3:37 pm] –
I would buy at least 10 pieces of bluepill-type F4 board, if the price is reasonable (~5 EUR).i would expect closer to 10€ (assuming it’s with all the bells & whistles), which i would still find great value if you compare it to a regular bluepill, and @ 10€ i’d buy 10
but when making this, it’ll probably make a lot of sense to also see if a budget version isn’t feasible. usb host, lipo charging, … it’s all very fancy, but who really needs it on every board. a basic version with just decent adc, powerful microcontroller, sd card & usb slave as close as possible to 5€ would also be awesome.
As a reference, here are the possible options for our BluePill F4 boards and the corresponding changes:
CPU
|
F103 ____________________ |
F405 ____________________ |
|
C11=0R C14=0R +R8 |
C11=2u2 C14=2u2 -R8 |
Headers
|
Yes ____________________ |
No ____________________ |
|
+J1 +J2 |
-J1 -J2 |
Voltage Sense
|
Yes ____________________ |
No ____________________ |
|
+R21 +R22 |
-R21 -R22 |
Power LED
|
Yes ____________________ |
No ____________________ |
|
+D1 +R2 |
-D1 -R2 |
User LED
|
RGB ____________________ |
PC13 only ____________________ |
No ____________________ |
|
D2=RGB1616 +R3 +R14 +R15 |
D2=LED0603 +R3 -R14 -R15 |
-D2 -R3 -R14 -R15 |
User Button
|
Yes ____________________ |
No ____________________ |
| +R5 | -R5 |
Analog LDO
|
Yes ____________________ |
No ____________________ |
|
-L1 +U2 |
+L1 -U2 |
LiPo Charger
|
Yes ____________________ |
No ____________________ |
|
+C19 +C20 +D4 +Q1 +R17 +R18 -R19 -R20 +U5 |
-C19 -C20 -D4 -Q1 -R17 -R18 -R19 -+R20 -U5 |
SDCard
|
Yes ____________________ |
No ____________________ |
|
+C16 +J4 +R16 |
-C16 -J4 -R16 |
USB
|
OTG ____________________ |
Device ____________________ |
No ____________________ |
|
+J5 +R7 +R9 +R10 +R11 +R12 +R13 +U4 |
+J5 -R7 +R9 +R10 -R11 -R12 -R13 -U4 |
-J5 -R7 -R9 -R10 -R11 -R12 -R13 -U4 |
As you can see from the above tables and if we ignore the non-significant passive components:
- The analog LDO feature only adds the U2 AP2112K3.3-TRG1 chip ($2.21 for 10 PCS on AliExpress)
- The LiPo charger feature adds a Schottky diode D4 ($0.93 for 100 PCS on AliExpress), a MOSFET Q1 ($0.88 for 20 PCS on AliExpress) and the MCP73812T-420I/OT U5 charger chip itself ($4.80 for 5 PCS on AliExpress), for a total of ~ $1 in extremely small quantities
- The SDCard feature only adds the corresponding J4 connector ($2.30 for 10 PCS on AliExpress)
- The USB OTG feature only adds the SY680 U4 USB switch chip ($0.85 for 5 PCS on AliExpress)
All in all, the total increase in cost between the minimum version and the full-featured version is only $1.62 in ultra-small quantities, whereas we are speaking of an increase of $0.50 for a change from 2-layer to 4-layer design…
The main cost in this board is of course the STM32F405RGT6 ($42.75 for 10 PCS at AliExpress).
People will sit down and weight up do I buy a Blue pill or do I buy the F4 pill. The main reason people will buy the F4 pill over a blue pill will be if they want extra features that the blue pill doesn’t have and r will to pay a little extra to have the extra features.
[flyboy74 – Sat Sep 08, 2018 12:24 am] –
For the small increase in BOM to have fully featured IMO the extra features is more likely to increase sales much more than the slightly increased price will decrease sales.People will sit down and weight up do I buy a Blue pill or do I buy the F4 pill. The main reason people will buy the F4 pill over a blue pill will be if they want extra features that the blue pill doesn’t have and r will to pay a little extra to have the extra features.
How about also paired with a worse mcu? the full featured version with a f4 or f7, and a more basic version with a cheaper f1 (STM32f103RET6? 1.5$ a piece in small quantities, 64k ram, 512k flash, has SDIO)
These things are very price sensitive, i’m definitely down for some near 10$ boards of this kind, but if we also got one close to 5$, i’d buy some of those too!
[Squonk42 – Fri Sep 07, 2018 8:27 pm] –
No, actually only a few pins are added connected to port C. Out of them, PC8-12 are used for SDIO, thus only PC0-7 are not present on the LQFP48 package. The BluePill F4 uses PC8-12 for the built-in SD Card, and PC0 for controlling the USB VBUS switch. PC1-7 are exposed as soldering pads with a 1.27 mm pitch on the bottom side. Besides their standard GPIO function, their only interesting function would be for exposing the I2S interface.
if it is possible, i’d suggest to route the PC0-7 pins to headers, the solder pads are kind of small and i’m thinking some may eventually be disappointed that PC0-7 are ‘unusable’
[ag123 – Sat Sep 08, 2018 8:52 am] –[Squonk42 – Fri Sep 07, 2018 8:27 pm] –
No, actually only a few pins are added connected to port C. Out of them, PC8-12 are used for SDIO, thus only PC0-7 are not present on the LQFP48 package. The BluePill F4 uses PC8-12 for the built-in SD Card, and PC0 for controlling the USB VBUS switch. PC1-7 are exposed as soldering pads with a 1.27 mm pitch on the bottom side. Besides their standard GPIO function, their only interesting function would be for exposing the I2S interface.if it is possible, i’d suggest to route the PC0-7 pins to headers, the solder pads are kind of small and i’m thinking some may eventually be disappointed that PC0-7 are ‘unusable’
Then the board would have to be 4 pins longer. That’s not impossible, but then we ditch the bluepill formfactor.
What usecases do you have in mind that would need the extra 7 pins and such a small board?
design decisions such as not routing pc0-pc7 to headers may be a little myopic as the board would be available for ‘general usage’
we’d not know who use the board for what
i checked the specs pc0-pc7 are mainly gpio pins, but then some of them has functions like ADC, which i’d think there are adequate pins to go around.
And there are alternate functions, which includes some of those like SPI2 , USB OTG etc
even as gpio pins they are useful for various purposes, e.g. if you are using lots of SPI, then the gpio pins can be used as CS pins and for various other purposes such as driving an ILI9341 lcd, various auxillary pins (e.g. command / data) , led, are needed beyond simply SPI
and if one is using a ‘parallel’ icd and say uses 8-16 data pins and some additional io pins in addition e.g. led, command/data etc, the pins consumption would quickly use up whatever is there on this board
hopefully it would attract a manufacturer to mass produce them as only then the per board bom prices may be lower
if it ever become successful, we may even see 3rd partly makers distributing ‘capes’ or ‘shields’ for them, just as it has been after arduino started
imagine one day people start talking about a stm32duino lcd ‘shield’ and for precisely this board
Actually, PC0 is already used internally for VBUS_EN and PC1 for voltage sense, so there are only PC2-PC7 left, i.e. 6 pins. And if you check the layout carefully, you will see that bringing the PC2-PC7 pins on headers is almost impossible on such a narrow board, or you are more than welcome to try, as it is an open-hardware design 
And if you look carefully at the alternate functions for these pins PC2-PC7, you find only a few useful functions: SPI_MOSI/MISO (also available on PB14-15), I2S (I2S2_SD, I2S2ext_SD, I2S2_MCK and I2S3_MCK), external USB HS PHY interface, Ethernet MII, SDIO 6-bit mode SDIO_D6-7 data signals and USART6_TX/RX (DCMI is not present on F405). So out of these, only I2S and UART6 are really interesting, making these pins the least interesting in the package. Thus, I did my best to keep them available and have these extra pins aligned and using a standard 1.27 mm pitch as solder pads, as I don’t see a better way to expose them.
Keeping the BluePill form factor is IMHO a good thing : this is a prototype board, designed to be small and used with breadboards. This concept proved successful, with the original BluePill. The F4 will add steroids to the concept.
However, if you absolutely want all exposed pins, take a larger, “square” board featuring an F4 and play with it, but there is no need to reinvent the BlackPill F4 you can already find on AliExpress for < $10.
no worries, a BP F4 still has its merits, the motivations and objectives are different
on a different note, rather than using a breadboard, i tend to use ‘dupont wires’
https://www.ebay.com/bhp/dupont-wire
this is a rather expensive way to connect the soc board to (breakout) modules or lcd etc. however, if the connections are after all point to point it seemed fairly common i.e. 1 gpio to 1 function, it alleviates concerns about a ‘breadboard layout’, in a sense i’m able to wire up those double row pins for different purposes as those are simply point to point dupont wires to the other modules. it also alleviates concerns about how the (header) pins are actually laid out on the board, as the wires can be simply jumpered to different pins on the board to go to the same soc pin (i.e. ‘shields’ tend to need fixed physically located pins, but ‘dupont wires’ alleviate that)
off-topic:
this ‘connectivity mess’ didn’t just afflict arduino, the linux community struggles with that and invented the ‘device tree’, or rather it starts from power pc and it becomes widely adopted
https://elinux.org/images/1/19/Dynamic- … ote-v3.pdf
the traditional ‘hardware is at fixed location’ model is challenged
in a fpga, hardware can be ‘reconfigured’, on an arduino, the user decides where to plug his/her ‘peripherals’ e.g. a led, a button switch etc- ‘hardware become software’
