http://www.stm32duino.com/viewtopic.php … =20#p25900
michael_l wrote:Thanks. This is good news ! I’m running out of ram in my STM32F103 and will have to switch to STM32F4 soon.
Going a bit off-topic here but are there any STM32F4 boards that are size of a blue pill available ? Of course all F4 mcu’s are not yet supported by this project but if I find a small STM32F4 board I can start working on the variant config based on this project.
stephen
http://www.ebay.com/itm/RACING-F4-EVO-B … 2316439845
http://www.stm32duino.com/viewtopic.php?t=1414
https://www.analoglamb.com/product/seeduino-stm32f405/
http://www.ebay.com/sch/i.html?_odkw=st … n&_sacat=0
https://www.olimex.com/Products/ARM/ST/STM32-H405/
Dimensions: (61 x 34)mm ~ (2.4 x 1.3)”
i like olimex for their pretty good documentation and on the product web
http://www.ebay.com/sch/i.html?_from=R4 … 05&_sop=15
and these
http://www.ebay.com/sch/i.html?_from=R4 … er&_sop=15
and go totally bare metal
https://it.aliexpress.com/item/VCT6-STM … 2b5ffdbf4d
Beat me 
ahahah
http://www.stm32duino.com/viewtopic.php … 274#p26260
actually with f405 you would have gotten 1m flash, but with f407 you may get 512k flash instead, i think the ram is the same at 196k
the f407 has an internal 100mbps ethernet mac (needs an external RMII PHY) and a 200mbps usb 2.0 high speed frontend (needs an external PHY)
but i’d think for the mini boards it might be difficult to patch that up unless those pins are broken out after all
if you want the f405, you may want to check out olimex board (quite small Dimensions: (61 x 34)mm ~ (2.4 x 1.3)”) a few post earlier, the price is quite competitive (but i think shipping charges is somewhat higher in europe (compared to china perhaps), but this might be low if you are after all based in europe or us)
the thing about olimex is they post the schematic and manuals on the product web, i think that’s a valuable doc
actually with f405 you would have gotten 1m flash, but with f407 you may get 512k flash instead, i think the ram is the same at 196k
the f407 has an internal 100mbps ethernet mac (needs an external RMII PHY) and a 200mbps usb 2.0 high speed frontend (needs an external PHY)
but i’d think for the mini boards it might be difficult to patch that up unless those pins are broken out after all
if you want the f405, you may want to check out olimex board (quite small Dimensions: (61 x 34)mm ~ (2.4 x 1.3)”) a few post earlier, the price is quite competitive (but i think shipping charges is somewhat higher in europe (compared to china perhaps), but this might be low if you are after all based in europe or us)
the thing about olimex is they post the schematic and manuals on the product web, i think that’s a valuable doc
you could literally get it from the source and ….
https://store.micropython.org/#/products/PYBv1_1
https://store.micropython.org/#/store
around 33mm x 43mm (1.3″ x 1.7″), less those connecting holes – STM32F405
4 leds, 2 buttons (usr & reset)
the designers even throw in a micro sd card connector and a 3 axis accelerometer
it fits *tiny* specs, could be among top 3 winners fitting ‘tiny’ specs
similar board found on ebay, search for micropython
http://www.ebay.com/itm/MicroPython-PyB … SwdGFYykVN
Do you need F4? there is a few F1 board with F103RCT and RET MCUs, which have 3 spi ports, 5 uarts, and 48 to 64KB of RAM.
you could literally get it from the source and ….
https://store.micropython.org/#/products/PYBv1_1
https://store.micropython.org/#/store
around 33mm x 43mm (1.3″ x 1.7″), less those connecting holes – STM32F405
it fits *tiny* specs, could be among top 3 winners fitting ‘tiny’ specs
similar board found on ebay, search for micropython
http://www.ebay.com/itm/MicroPython-PyB … SwdGFYykVN
i’m thinking with boards like the tiny micropython + lcd + stm32duino + a coin cell battery, you could literally make a smart watch out of it
The biggest chip that will fit on a Blue Pill is a LQFP-48.
I was wrong! Taking another look at the STM32 F4 product line today there are plenty of 32 & 48 pin variants.
Perhaps better to look for F3 variants (as there are 48 pin versions of this chip).
A quick look found a couple of tiny F303s on AliExpress:
40x21mm
https://www.aliexpress.com/item/Free-Sh … d2f5053191
20x28mm
https://www.aliexpress.com/item/Hot-New … d2f5053191
Pity the pinouts are optimised for flight controllers, rather than breadboards!
it seemed even on the f3 series (which has a very fast adc)
http://www.st.com/content/st_com/en/pro … tId=SS1576
both ram and flash are considerably lower compared to f405, f407
on top of that f407 adds a hardware fpu, additional peripherals like ethernet mac, fast usb 2.0 and a fast and advanced dma controller (compared to f103) and it adds additional things like fsmc on the stm32f407ve, stm32f407ze, stm32f407vg, stm32f407zg series
imho the f407 high density socs run more like mini pcs, smart phones and less like the arduino uno
https://www.youtube.com/watch?v=0ETyFmAMFjY
the smallest well made board currently is possibly the f405 based micro python board
https://store.micropython.org/#/products/PYBv1_1
and the board is somewhat less than a smallest possible only because it breaks out a significant number of pins from the f405 and it is those breakout pins which serve a useful interfacing purpose
In ideal case, there would be a Teensy 4.x variant with WiFi or BT5 support.
I have Teensys in a number of projects and they are very sweet, especially the 3.5/3.6 models which have enough grunt to do real time audio processing and a range of other fun things. As you say, Paul’s software support for Teensy is exceptional, and I’d guess that the cost of the boards includes something to recoup the costs of prototype and software development. Paul has commented that the audio library took nearly a year (obviously not full time!) to perfect.
Paul is fairly well entrenched with NXP, so I think it unlikely that a Teensy with an STM processor is likely in the near future.
Another interesting mini board is the $10US C.H.I.P with an Allwinner R8 (Cortex A8 – Gigahertz class) processor, WiFi, etc. https://docs.getchip.com/chip.html
Of course this is moving away from the core subject here – STM F4 mini boards.
Perhaps we should be looking at the STM H7 series – to keep stretching the performance edge!
Richard
I think that F7 and H7 are not yet ready for prime time. They have very nice architecture, but they need to reduce the geometry to lower cost, improve performance, and reduce power consumption. H7 with 1.8V implementation could be in the main stream in 5 years.
vs those cortex-A richly ram equipped boards with possibly 10s of megs to 100s of megs to gigabytes of memory and flash but perhaps has no integrated adc, dac etc e.g. raspberry pi, beagle bone black etc etc
one of those issues is that things like micropython (https://store.micropython.org/store/#/store) or perhaps elua (http://www.eluaproject.net/) etc do use up quite a bit of ram. and it would be like packing an elephant in a box to run them say on a bluepill, maple mini etc
and if one wants to go to a full blown micro-windows gui run an spi lcd screen, touch screen, rich menus with bitmaps/icons, run dma talking to usb host, run dma taling to micro sd card doing sdfat32 etc and still run analog pins, display oscilloscope, logic analyzer traces etc my guess is 20k of sram would easily run out before it could even be possible
Like the quadcopter controllers in size, but without the special headers.
Not too many pre-dedicated pins either.
There is plenty of good support now for F4s – each of the streams has different features available (for now). E.g. DanielEff’s has FPU, the others haven’t enabled it yet (as of last week)…
Do you have a first project in mind?
https://www.tindie.com/products/TleraCo … ent-board/
https://www.tindie.com/products/TleraCo … ent-board/
https://www.tindie.com/products/TleraCo … ent-board/
I believe I heard about them here on the forum.
http://www.ebay.com/itm/STM32F407VGT6-A … 2355411407
but i’m wondering if ‘hard wiring’ boot0, boot1 with a dip switch is after all a ‘good thing’, if one wants to use that for another purpose, one may need to remove the dip switch
note that these webs are in chinese
https://vcc-gnd.world.taobao.com/
http://www.vcc-gnd.com/
saw this couldn’t resist & grabbed a piece, 4cmx5cm and the monster number of pins, my guess is this is as much as you can squeeze on the board for the stm32f407vet6 with possibly all the pins broken out
http://www.ebay.com/itm/Mini-core-board … 2309828654
note this web is in chinese, the photos is pretty much self descriptive
https://world.taobao.com/item/523361737 … 4.2.0ECYor
—
just bought this new mini f4 board bought on impulse
after i click buy i looked closer at the board photos, they use ceramic resonator rather than crystal oscillator, not sure whether to regret about it
ceremic resonator has been known to ‘mess up the RTC’ poor timekeeping, poor frequency stability vs crystal
https://forum.arduino.cc/index.php?topic=60662.0
http://forum.arduino.cc/index.php?topic=69316.15
unfortunately, this is as mini a f407vet board as i can find for now and one which is decently well build (and not too high priced). u’d only need to look at the monster number of pins on the headers, that’s possibly as little area to put all that headers breaking out all the pins
note that these webs are in chinese
https://vcc-gnd.world.taobao.com/
http://www.vcc-gnd.com/
saw this couldn’t resist & grabbed a piece, 4cmx5cm and the monster number of pins, my guess is this is as much as you can squeeze on the board for the stm32f407vet6 with possibly all the pins broken out
http://www.ebay.com/itm/Mini-core-board … 2309828654
note this web is in chinese, the photos is pretty much self descriptive
https://world.taobao.com/item/523361737 … 4.2.0ECYor
https://en.wikipedia.org/wiki/Ceramic_resonator
but i’d think that’d at least beat a simple RC oscillator in terms of frequency-voltage sensitivity
RC oscillators are possibly even more sensitive to voltage swings and temperature swings vs a ceramic resonator
—–
my goof NX5032GA seemed to be a smd crystal, rather than ceramic resonator
http://www.ndk.com/images/products/cata … SU-2_e.pdf
it seemed the ‘epson’ 32768khz part is also an smd crystal just that i’m not sure what is the part number for it
i’d guess a little more research is needed about these smt crystals
they seem to be some sort of mems ‘tuning fork’ oscillators
https://www.digikey.com/en/product-high … z-crystals
https://en.wikipedia.org/wiki/Ceramic_resonator
but i’d think that’d at least beat a simple RC oscillator in terms of frequency-voltage sensitivity
RC oscillators are possibly even more sensitive to voltage swings and temperature swings vs a ceramic resonator
—–
my goof NX5032GA seemed to be a smd crystal, rather than ceramic resonator
http://www.ndk.com/images/products/cata … SU-2_e.pdf
it seemed the ‘epson’ 32768khz part is also an smd crystal just that i’m not sure what is the part number for it
i’d guess a little more research is needed about these smt crystals
http://www.vcc-gnd.com
https://vcc-gnd.world.taobao.com/
with those specs 512MB NAND Flash and 256Mb SDRAM, i’d think stm32f4 can even compete with the beefy raspberry PIs
https://world.taobao.com/item/544433769 … 8.8.izh4HI
and F4 wins big in terms of the number of SPI, UART, DAC, ADC, ethernet mac etc and the sheer number of gpio pins available for use
and strictly speaking this qualifies as a mini board if u consider that the STM32F429{IIT6 or IGT6) takes a huge real estate on the board itself, it is a monster of a soc just by chip surface area alone, the board is merely borderline bigger than the chip itself
the other surprise is for biz like epson
http://www5.epsondevice.com/en/products/
http://www.ndk.com/images/products/cata … SU-2_e.pdf
my impression of crystals are those metal tin cans while Epson & NDK seemed to have made them look very different, i’m wondering how would it be possible to tell between a crystal vs ceramic resonator by its looks
https://it.aliexpress.com/item/STM32F4D … 49543.html
Some observations:
– the color of the board is black with quite nice protective layer and clear labeling
– the RTC xtal is not the classic style; instead it is the long cylinder type
Compared to the F407vet6 board that I am using in a 6 motor speed controller (ref https://it.aliexpress.com/item/STM32F40 … 85751.html), there are the following differences
– the vgt6 board is larger
– the vgt6 board is missing the SWD connector pins
– the vgt6 board is missing the EEPROM
– the vgt6 board is missing the SD drive
– the vgt6 board is missing the boot0 and boot1 switches
– the vgt6 board has a user button
I have the full documentation for the vet6 board, but have not yet found the vgt6 board documentation. The board label CJMCU-407 didn’t give any proper leads in Google.
Both boards came without the headers soldered. I do like that because it allows me to use the machine pins which are highly recommended over the standard pins.
PS. For 2 motor and 4 motor speed controllers, I am using Teensy 3.2 and 3.5
vgt6 has got 1 meg of flash on it, it is ‘plenty’ for mcus, my guess is this kind of mcus/boards with big flash memories are useful for ‘multi-purpose’ usage
i think the pebble smartwatch is made with stm32f4 with pretty much 1m flash, hence one could install ‘applets’ on the same mcu and basically run the different applets. the large flash can also be used to store data / scripts or used as storage
i think micropython https://micropython.org/ is one of those that use a good fraction of on chip flash and in addition use an sd card perhaps for scripts and other data
just 2 cents
I’d be interested in the schematic, as I have one on the way as well. Given the lack of onboard extras (memory, special purpose headers) and the handy silkscreen printing on the back, it shouldn’t be too hard to trace the few lines going to the USB – almost certainly +5, GND, PA11, PA12 (USB OTG FS default pins), the switches – one is likely to be PA0 (SYS-WKUP) and LEDS.
BOOT0, BOOT1 (BOOT0 and PB2) seem to be mapped next to PB2/PE10. Looking at the back of the board, I’d guess they’re on the inside row and pulled up, with GND pins on the outside row.
I hope this helps. If you want to create a “formal” variant for any of the current code sets (Maple, STM32GENERIC, github/STM32UDINO), I can give you a hand.
I like your “funny coloured” designation for the board. It just highlights that we’ll need to find a better way to designate variants.
Stephen (@zmemw16) and I continued Roger’s redpill – bluepill theme with the “Black VET407VET” series naming, and it’s not ideal.
Perhaps something more pragmatic – like the chip designation + number of GPIO pins &/or the board size, for unbranded boards…?
Richard
My head is still spinning around the right solution for STM32F407 library support. I really like the simplicity of Arduino IDE. It is the easiest for youngsters to learn. For my own projects, I have been using the Standard Peripheral Library for many years mainly because there was a native support for it in EmBlocks/EmBitz. I was planning to shift to LibOpenCm3, but it felt stalling. After some trial projects, I shifted to Unicore-Mx. It seems to work well in Unix platform, but I haven’t yet abandoned Windows. Currently, I am using STM32CubeF4 HAL library with EmBitz.
My preference for F4 support in Arduino is to leave the HAL still quite visible for the apps without too much convolution by Arduino/LeafLab history. In that way the next transition to F7 and H7 would be less painful.
Cheers, Ollie
it seemed certain f4 nucleo boards is supported, mbed is pretty much another arduino style platform
and as well ChibiOS which seem like a rather elaborate RTOS stack with it own pretty elaborate HAL libraries
but i’ve not really tried any of those out
my guess is STM’s Cube HAL, is pretty much an ‘industry standard’ given it is pretty much from ST and to an extent supported by ST and its generic support across literally the full stm32 series. the total set of HAL libraries is some 100megs today for all the mcu ranges, it would be difficult for a public open sourced effort to replicate that. however, Cube HAL do have its issues / bugs etc. in particular for the smaller mcu’s it seemed it may lead to code bloat, bigger binary sizes if one is not too careful with including the relevant components
as for arduino platform, my thoughts are that the sketches works pretty much pretty well (in fact exceeding the ‘uno’) on stm32 as well. but the effort is very much ‘development from scratch’ for the libmaple core itself, and today stm’s core and daniel’s stmgeneric cores based on HAL are coming in and offering an interesting and viable way forwards that takes ‘arduino’ very much beyond its modest ‘uno’ roots
Yes, simple and standard is the way to go – leaving HAL (and LL) libraries visible for anything but the most basic tasks.
For example, there’s a standard ADC library in Arduino that can read an ADC sample and write to the DAC (PWM!!!) – all expenses paid. For anything else, direct access to the STM libraries – particularly as the HAL libraries are fairly high level and very well documented – is best. We are, after all, working with embedded systems, not Linux.
I’ve found that the HAL libraries are sometimes a bit slow for time sensitive work (e.g. real-time audio) and use mixed LL and HAL quite successfully. HAL for its configuration simplicity; LL for fast interrupt and DMA servicing . This approach is apparently OK, as I borrowed some early code from the STM “Cube” “MIX” examples for ADC. It also works fairly seamlessly, most of the time, as the HAL tends to use the LL routines for “intimate” configuration tasks.
I hope your head stops spinning soon!
Richard
https://www.sparkfun.com/products/14186
It comes with an SD card socket, USB (FS), I2C, SPI and 6 other GPIOs broken out onto its 2 x 8 pin headers.
There’s also an OV7725 camera module on board!
Footprint is around 45 x 30 mm.
All for $65 US.
The cheapest solutions for F7 at the moment are the Nucleo boards from STM. I don’t like them anymore; they are too bulky.
I do agree that LL is required for time critical tasks. It seems to me that HAL is missing some basic functionality. I was trying to do EXTI on F407 without LL, but I didn’t find all required functionality in HAL. After awhile, I cleaned all LL calls from my application and replaced them with my own macros for the EXTI register manipulation (such as interrupt mask management and clearing interrupts).
After several years of using STM libraries, I am still critical about their style where the naming conventions are lacking consistency and the code is very bloated. But in real life, the HAL seems the safest bet at the moment.
EXTI on ADC or EXTI generally?
@DanielEff and I have been talking about some neater ADCinit() code for his STM32GENERIC implementation under https://github.com/danieleff/STM32GENERIC/issues/6
To use the existing HAL (and LL) code requires a lot of intimate knowledge of the ADC and DMA registers. We’re looking at functional (rather than register setting) code.
ADC EXTI triggering is one of the areas where special treatment will be required.
I agree that the HAL code tends to try to deal with every possible eventuality (like Linux drivers) rather than simply ignoring the flags that are irrelevant for a particular application.
I’ve had some success with Mixed HAL/LL code for the ADCs. Initialise with HAL (slower, but simpler), then attach interrupts to LL code for fast end of conversion handling, etc.
My reference was for the minimal EXTI usage. My expectation was that it can be done completely in HAL, but I didn’t find all the required functions. I had to use LL or direct register manipulation.
In the real life applications you are referring, in addition of ADC, EXTI, and DMA, you have often TIM and NVIC involved. The use cases have so many variants, that it is quite difficult to have Arduino IDE library to support most of them.
We’ll just have to work on something general enough to be useful, but allow easy customisation.
The NVIC isn’t so much of an issue, as the interrupts are pretty specific for a particular task, even though there are quite a few of them.
DMA is relatively straightforward, for most cases – the unpacking of values is a little messy for the multiple ADC modes, but is mainly done in user code.
TIMs are a little more difficult as there are 14 options and these are spread across both peripheral buses, and have a mix of 16 and 32 bit counters!
EXTI will be yet another adventure…
Interesting thing is that it has 25Mhz ceramic resonator.
i’m procrastinating on soldering that huge number of pins for the headers, the extreme of which some of the silkscreen labels would be covered by the headers. i’m thinking about ‘inverting’ the 4 debug pins so that all the headers would be ‘below’
the sheer compactness is staggering, i placed it side by side with a maple mini (about the same size for blue pill i’d think), the length is shorter than blue pill/maple mini and the breadth is about double that of blue pill / maple mini, the stm32f4vet chip itself takes up the lion’s share of the board
and for what’s worth, it seem the board makers shipped with those ‘legendary’ 6pf Epson crystals, not the ‘cheapo’ ebay 3 cents one (but strange couldn’t find the fitting part numbers)
http://www5.epsondevice.com/en/products/
http://www.stm32duino.com/viewtopic.php … 582#p27582
http://www.stm32duino.com/viewtopic.php … 409#p27407
off topic, japan still holds an old trophy for being a master at quartz crystals
https://www.watchreport.com/the-most-ac … the-world/
http://www.livemint.com/Sundayapp/ipfLC … world.html
but obviously, we probably can’t expect the same as those ‘grand seiko’ luxury watches for these boards
for what is worth even touching the pins and adding some extra pf capacitance to the crystal would throw the oscillator seconds off the benchmark
http://www.stm32duino.com/viewtopic.php … 409#p27426
In this application the normal connectors would not work very well. It would be hard to remove the board without bending the pins. My solution was to use the machine pins which do require less force to insert and remove the boards. At the same time, the electrical connection with the round pins/holes is better that with the traditional square pins/holes.
Have you tried those small proto boards with through holes. There it is very easy and fast to solder sockets for multipin components and solder the two-leg components directly. Based on some recommendations from Uncle Google, I did use the wire wrap wires for soldered connections. The stripping and soldering was not a problem, but the insulation didn’t tolerate the hot soldering iron.
Now I have returned back to enamel wires for all connections – thin wires for signals and thicker for power. The striping is a major challenge. The solution was to find the right wire types that can be stripped with very hot soldering tip. I have some enamel wires that have so tough cover that no amount of heat and soldering paste flux can strip them. I did use sandpaper for the stripping, but now I have given up to use them.
It is a little bit slow to change between the normal temperature and the stripping temperature, but it is still faster and more reliable than any other method I have used. When I am lazy, I am not even changing the temperature, instead I do the soldering with the “too high” temperature.
If and when you make the wiring mistakes or change plans, it is very easy to take the old wires completely out or reroute them.
I have been using the mesh of single wires – especially with the breadboards – but that is not good for robots or for the youngsters playing with the robots. The soldered enamel wires are very robust. With soldered wires, you can avoid the breadboard problems in lost female contacts and bad male wiring pins.
i’ve seen this http://elm-chan.org/docs/wire/wiring_e.html
it is quite inspiring/awesome, just that i’m not too sure about my own soldering skills to be able to do just that, but i’d think it’s nevertheless something good to try
Has anyone looked inside the EEPROM to see if it’s just a resource, or has any magic pre-installed?
Also, I tend to substitute long pin headers on my boards, rather using than the shorter ones supplied, so that I can attach logic analyser probes or put several wire wraps on one pin. Where there’s enough space I use long-pin female headers – which provide an extra connection option. It’s really useful for debugging with the logic analyser as “Dupont wire” (rainbow cables with individual header pins or sockets) pins are much more likely to stay in place than test clips.
Embedding the board in a piece of EVA foam (non-conductive) keeps the bottom pins out of trouble when they’re not needed.
It was really hard to solder the pins next to the debug header. I did the side ones first (which as a good idea) and then the cross piece. I insert the header pins into a socket, while soldering, to keep them straight. BTW, the poor solder joints in the front row have been fixed!
Next time, I’ll insert the header pins from the top, solder on the bottom and then strip the black plastic former, so that the silkscreen is fully exposed.
Richard
I like your ideas about the long Dupont pins on both sides. For development and debugging that is the best way. For deployment, I do recommend the round machine pins. With the female Dupont headers, the cutting to proper length is frustrating. My method is to use bandsaw and a sander. With machine pins, the cutting can be done with pliers in the same way as the male headers are adjusted. If you are using white female machine pin headers, you can use color markers to identify the pin locations.
It would be nice if this board would gain popularity due its small size, nice functionality, high performance, and low cost. That would increase its support and further popularity.
i’m thinking of using styrofoam (Polystyrene) to plug the pins in, just that i’m not too sure if styrofoam boards may create static electricity that perhaps cause some shorts. but using say stoyforoam may be a good way to hold the board say in place in a case say without the mounting screws
oh by the way the manufacturer/originator web site apparently have various info such as schematics etc, they are in chinese though.
but the symbols, part numbers etc would pretty much be in alphabets, you could try putting the urls in google translate if it helps to make sense of the web
http://www.vcc-gnd.com/
http://www.vcc-gnd.com/cp/stm32hxb/stm32f4xxhexinban/
someone has uploaded various info and schematic into the wiki as well
http://wiki.stm32duino.com/index.php?ti … 7VET6_Mini
http://wiki.stm32duino.com/images/6/69/ … ematic.pdf
my guess too about the eeprom is it is likely to be uninitialised, normally it is rather popular to store some info in eeprom to identify the board. this could help the firmware tell what board it is running on as it would otherwise be indistinguishable. but i doubt such info is stored in the eeprom, in particular across all the same boards
Just a simple box with a lip inside for the edge of the board to sit on – for a top mount solution.
For a slide-in solution, a slot below the top edge could work.
Richard
My hold-back is that I am still learning the best practices for F4 CubeMx HAL and not yet ready to jump into F7. My temptation is increased with the new technology for fast control. Instead of doing hundreds of PID loops per second, the new race controllers are doing thousands of PID loops per second. The classic analog servo signal (1 .. 2 ms) is too slow and inaccurate for that. It is replaced with digital DSHOT protocol where the microsecond level pulse streams are driven with DMA channels between the host and Electronic Speed Controller. Perhaps DSHOT will be used also for the coming fast servos 
I will jump to the multimotor BLDC motor control using DSHOT600 (or perhaps DSHOT1200) with F407VE based main controller. The Racestar RS20Ax4 at Aliexpress https://www.aliexpress.com/item/New-Arr … 42226.html for $34 is a good price for 4 motor controller with 5V regulator for the main board. I did order that with four gimbal motors for robotic application.
If the next revision of AnyFC F7 mini board will have MPU9255 instead of the classic MPU6000, I would purchase it now for evaluation. 
i’ve been looking at those f103vet/zet vs f407vet/zet, apparently the price differential between the f3 vet/zet vs f4 vet/zet is not as large as say compared to a blue pill / maple mini $2. given the significantly higher performance + the increased ram + flash + additional soc resources (e.g. fpu), i decided to just go with f4, would probably look at f7 another time
- STM32F745VGT6, the small flight controller
- STM32F407VET6, the handy blue board I am using in a multi-motor controller
- STM32F407VGT6, the nice black board for medium size vanilla applications
Top view
Bottom view. Here you can see the machine pins used in lieu of the square pins.
The F7 board was designed by Sami Korhonen (sambas) in 2016 and it is really nice with very compact cabling to UART and other peripheral devices. First, I criticized the usage of MPU6000, but for practical terms this 6 DOF IMU is adequate for my robotic applications.
Cheers, Ollie
PS. Sorry for my mistake in sharing – it was private and the public view was not enabled 
The Chinese Miro-Python community has build a small form factor STM32F4 dev board. I do believe there is 2 versions of it STMF411 and STMF405 with 8MB flash storage.
This is the 1 being build by the community https://item.taobao.com/item.htm?id=551020358896
This is a copy being built by elecrow https://www.aliexpress.com/item/Elecrow … 56520.html
https://www.aliexpress.com/item/IRS2092 … 07693.html
[stevestrong – Mon Jan 07, 2019 2:26 pm] –
Another small size F407 (VET6) board with SD slot, USB-C and lots of pins (a real F4 “black pill”?):
https://www.aliexpress.com/item/IRS2092 … 07693.html
Wow that is even smaller again. Very little info on the board but I might buy 1.
I asked the seller about the SD slot, whether SDIO or SPI is connected to it, got no reply so far.
[stevestrong – Mon Jan 07, 2019 9:08 pm] –
That’s right, no info, no schematic.
I asked the seller about the SD slot, whether SDIO or SPI is connected to it, got no reply so far.
I was hovering over buy for 2 of these before realising that also
This search turns up more results -> https://www.aliexpress.com/wholesale?ca … Board+VCT6
But all the images are the same with hardcoded chinese I might try googles phone translate app on it.
I did also see this but don’t think it is as good and you have to buy 2 pices https://www.aliexpress.com/item/STM32F1 … 26e960a81c
Me:
Hello,
Please can you provide the schematic for this board?
This will help me in my decision to buy.
Thanks
Vendor:
Do you have a circuit diagram?
Are all DCMI or FSMC or SDIO or Ethernet pins available?
If not, there is not much advantage compared to a bluepill, except more “normal” GPIOs.
But then the generic F4 mini board is better value, with even more pins and some additional components on-board at lower price.
It’s a bit of ‘fun’ at the end of the day
Main advantage for me is flash size – but then I could always use external SPI flash on BP/MM Less wiring is good.
[BennehBoy – Fri Jan 11, 2019 2:17 pm] –
Main advantage for me is flash size
Do you really have an application requiring more than 512kB flash? Wow.
The “best” (max) I could reach on F4VET6 was ~150kB having 4 HTML pages (+LwIP) in flash, with many debug lines…
I just purchased some colour OLED’s as an upgrade for my project, lot’s of bitmaps etc
I’ll submit a PR to the core if anyone wants to tinker.
EDIT – and I found some schematics…. https://github.com/project-sparthan/Fir … /Resources
Now have Button, LED, & SDIO confirmed
[stevestrong – Fri Jan 11, 2019 1:00 pm] –
Without a schematic is hard to imagine which pins are lead out to pin headers.
Are all DCMI or FSMC or SDIO or Ethernet pins available?
If not, there is not much advantage compared to a bluepill, except more “normal” GPIOs.
But then the generic F4 mini board is better value, with even more pins and some additional components on-board at lower price.
F407VET is a 100 pin package with 5 ports of 16 pins so 5 x 16 = 80 pins. Looking at the headers there is 4 rows of 20 pins so 80 pins total on header including power and ground pins but then there is also the swdio and swclk pins for st link header and the sd card slot as well as the pins used by the low speed clock. So doing the math even without a schematic it looks like everything is broken out.
I checked most of the peripherals and all the required pins are broken out.
- 20190121_223223.jpg (37.94 KiB) Viewed 574 times
at the lowest i see $8 shipped for the black vet6 board, it seemed prices has gone up somewhat, my guess is postage increased
https://www.aliexpress.com/item/STM32F4 … 81553.html
[ag123 – Thu Feb 07, 2019 11:01 pm] –
nice compact board, a little pricy for my flavor and i still have a couple of ‘fat’ boards lying around, so i’d make do with my ‘fat’ boards for now
at the lowest i see $8 shipped for the black vet6 board, it seemed prices has gone up somewhat, my guess is postage increased
https://www.aliexpress.com/item/STM32F4 … 81553.html
I mainly use the fat board for basic prototyping but it is too big for deployment in most of my robotic projects. I paid the higher price for the smaller board as it was more useful to me for deployment.
Considering they both have the same MCU I would hope other manufactures will copy the smaller board and the price will come down to cheaper than the fat board
[flyboy74 – Fri Feb 08, 2019 7:50 am] –
I mainly use the fat board for basic prototyping but it is too big for deployment in most of my robotic projects. I paid the higher price for the smaller board as it was more useful to me for deployment.Considering they both have the same MCU I would hope other manufactures will copy the smaller board and the price will come down to cheaper than the fat board
no worries, the small stm32f4 boards are indeed the attractive boards in part due to their small footprint, which solve various issues
it seemed if the query keywords is instead “stm32f407 mini” these would be the results and it seemed there are quite a handful starting from around $15
https://www.aliexpress.com/w/wholesale- … -mini.html
here is a query for keywords “stm32f407vet6 mini”
https://www.aliexpress.com/w/wholesale- … -mini.html
some additional boards are presented some of them mentioned prior
i noted that prices has gone up as those same boards back then are apparently priced lower based on casual memories
[ag123 – Fri Feb 08, 2019 3:36 pm] –
no worries, the small stm32f4 boards are indeed the attractive boards in part due to their small footprint, which solve various issues
it seemed if the query keywords is instead “stm32f407 mini” these would be the results and it seemed there are quite a handful starting from around $15
https://www.aliexpress.com/w/wholesale- … -mini.html
here is a query for keywords “stm32f407vet6 mini”
https://www.aliexpress.com/w/wholesale- … -mini.html
some additional boards are presented some of them mentioned prior
i noted that prices has gone up as those same boards back then are apparently priced lower based on casual memories
All those boards are bigger in size than the FK407M1 and all are more expensive and don’t have a USB type C or a SD card slot included.
[flyboy74 – Fri Feb 08, 2019 9:50 pm] –
All those boards are bigger in size than the FK407M1 and all are more expensive and don’t have a USB type C or a SD card slot included.
+1
i’ve got 2 pieces of
https://www.aliexpress.com/item/Embedde … 83336.html
though, but i vaguely remember that it used to cost less
yup and it don’t have USB type C, the uSD card slot is there, i remember that the size being about 2x the width of blue pill, the length is about the same as a blue pill.
nevertheless i think the FK407M1 you’ve got is more compact
i’ve once thought about using 1.37mm (1/20″) smd parts and connection pads (e.g. FPC) but i’ve never attempted to solder them myself prior hence i’m not too confident if i’d be able to work boards at those small dimensions
this is the home site in chinese
https://vcc-gnd.taobao.com/
https://item.taobao.com/item.htm?id=523361737493
it is local prices and are close to half that stated on aliexpress, that would support the notion that shipping costs has gone up
hence the same boards are pricier now when bought on aliexpress.
i think on taobao you could have it shipped overseas as well, but that shipping is separately charged, it would make sense if one is buying more than a say 1 piece of boards as the shipping costs alone based on the markup on aliexpress cost almost that of a board
interestingly they are now also offering a stm32f405rg micropython board (stated made-to-order) which is even more compact
https://item.taobao.com/item.htm?id=570751617176
the f405 ‘micropython’ board would fit the highly ‘space challenged’ cases such as drones etc (but there are drone specific boards covered in the earlier sections of this thread)
That’s the one with FSMC so best to check about.
all in the costs are high easily exceeding usd $10 for the international shipping and local shipping easily cost usd $1-3 within china itself
and for sea freight my recommendation is do not trust that with high value items as they aren’t insured and may possibly be crumpled / damaged by loads stacking on top or in a worse case simply lost. however, i’ve used that once to ship a transformer that weights some 1 kg, it wouldn’t make sense or is cost effective to do airfreight for that. bulky items work for sea freight as well, e.g. some sheet metal casings/enclosures. but i’ve since sourced locally rather than resort to these means as the costs, the bulk and the wait probably means it may be cheaper to source locally or find alternatives (e.g. for enclosures)
the main trouble is taobao is alibaba’s local equivalent of the chinese ebay or aliexpress, i.e. it is intended for chinese and locally within china. shipping is default local within china only – hence there is the additional shipping service offered by taobao for international shipping.
the webs and ads are all in chinese which would be a key challenge for someone who do not understand chinese to navigate
the solution to this challenge this days is to use things like google translate liberally, but i’d guess it would be literally difficult / cumbersome unless the costs are truly much lower. for one to a few pieces it isn’t worth all that trouble to confront the language challange and the hassle and dealing with separate shipping costs which are often pretty high. for that it would be simplier to just use the english and international based services e.g. amazon, ebay, aliexpress, gearbest etc.
there are a few exception though like i’ve mentioned prior for the f407vet mini board, price difference is almost usd$10 difference per board (on aliexpress it is usd $19) although on aliexpress the prices includes shipping. and on taobao the price of that board when converted to usd is around usd $9, it would make sense if you are buying more than a single piece if it is the case as shipping probably cost usd$10 or somewhat higher, but you can bundle a couple of boards. another interesting thing would be, i sometimes find things on taobao that are not found on aliexpress, ebay, i’d imagine those are individual or small makers or small retailers selling their wares directly on taobao within china itself.
[BennehBoy – Sat Feb 09, 2019 6:27 pm] –
The fk407m1’s are a bit cheaper if bought in a 5 pack -> https://www.aliexpress.com/item/STM32F4 … 84229.htmlThat’s the one with FSMC so best to check about.
i think this board is still a most cost effective / cheapest board considering that shipping is included as well
I would not recommend anyone use Taobao
I had to pay a large shipping fee because the company handing the overseas shipping decided to put the boards I ordered into a heavy cardboard box.
Also, I ended up with a duplicate order, because at the time, their Checkout system was very confusing, and it didn’t have any page confirming I was about to place the order .
Looking at the prices on Taobao, they are often only slightly cheaper than AliExpress, when you factor in the shipping cost.
