Is anyone interested in helping to make an Arduino Due which uses [edited:] a 100-pin STM32L471

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lkcl
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Is anyone interested in helping to make an Arduino Due which uses [edited:] a 100-pin STM32L471

Post by lkcl » Thu Sep 28, 2017 6:11 am

hi as i hinted at in the introduction hello here viewtopic.php?f=2&t=2629 i would like to (quickly) investigate the feasibility and viability of creating an Arduino Due compatible design which uses the 100-pin LQFP STM32F072V8T6.

the Reference Design from arduino.cc is in Eagle and is available publicly so it should be pretty straightforward and achievable. i've worked with the STM32F072 64-pin variant before so know what i'm doing, and love this particular series because it's crystal-less and really really low cost. $1.66 in 10k volumes as opposed to (in the case of the ATSAM3X8E) more money than a quad-core 1.5ghz 64-bit ARM Cortex A53 processor can be bought for.

i'm aware that the 072 is only 48mhz: that's absolutely fine for me, given that there's a reasonable chance of hitting a BOM target that's about the same as an 8-bit Arduino Mega 2560's r3.

so the real question is: would anybody be interested in helping to do a feasibility study for the pinouts, help review the schematics and board designs (which i will continuously publish online - immediately - with each and every single modification made, because that's what you do as a software libre and hardware designer) and so on.

even more than that, would anyone be interested to actually buy the resultant open hardware... or of course get it manufactured for themselves because it's an open, libre project? the reason i ask that is, this is the arduino forum for stm32 boards... but the only boards i see which are arduino hardware-compliant are for the *uno* pinouts which was one of the very very early boards, and you only get a small range of pin-compatibility.

... and i would like to make a board that is FULLY compatible with the FULL pinout range of the *DUE*.

that would mean that people could use the FULL range of available Arduino-compatible shields in their projects.
Last edited by lkcl on Mon Oct 02, 2017 7:31 pm, edited 3 times in total.

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RogerClark
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Re: Is anyone interested in helping to make an Arduino Due which uses a 100-pin STM32F072?

Post by RogerClark » Thu Sep 28, 2017 6:31 am

Welcome...

I'm curious why you chose the STM32F072?

Is this based on the cost of the processor.

From the specs' http://www.st.com/content/st_com/en/pro ... 072c8.html

Its RAM is only 16K, which is less even than the $2 BluePill boards. (STM32F103C8)

And, as you have already pointed out its only running at 48Mhz - which is again lower than the 72Mhz of the $2 BluePill

I guess the main attraction is the number of ports, on a 100 pin package ??

Most people seem to like using the BluePill as its cheap and powerful.

Or if they want more CPU performance people are using the F407, as it also has more RAM more Flash and more GPIO
(Well more of everything really)
The cost of the "Black" F407 boards is around $12 from AliExpress.

edogaldo
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Re: Is anyone interested in helping to make an Arduino Due which uses a 100-pin STM32F072?

Post by edogaldo » Thu Sep 28, 2017 7:23 am

I do agree with Roger, I don't think I could be interested in a lower value board just because it has a Due form factor.
Tip: why not thinking of a Due adapter for the existing and cheap F103/407 V/Z development boards?
There are some which are pretty popular..

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RogerClark
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Re: Is anyone interested in helping to make an Arduino Due which uses a 100-pin STM32F072?

Post by RogerClark » Thu Sep 28, 2017 8:15 am

edogaldo wrote:
Thu Sep 28, 2017 7:23 am
...
Tip: why not thinking of a Due adapter for the existing and cheap F103/407 V/Z development boards?
...
I had the same thought

Probably based on a F407, as you'd need a F103V or a F103Z to get enough pins and they are the same size as costs as the F407VET6 boards

(though I don't personally have anything that needs the Due form factor)

e.g.
https://www.aliexpress.com/item/New-STM ... 4de7935aae
Mini-version-STM32F407VET6-development-board-Cortex-M4-STM32-minimum-system-board.jpg
Mini-version-STM32F407VET6-development-board-Cortex-M4-STM32-minimum-system-board.jpg (221.05 KiB) Viewed 432 times
Mini-version-STM32F407VET6-development-board-Cortex-M4-STM32-minimum-system-board2.jpg
Mini-version-STM32F407VET6-development-board-Cortex-M4-STM32-minimum-system-board2.jpg (231.38 KiB) Viewed 432 times
US $10.93
Free shipping (at least to Australia)

lkcl
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Re: Is anyone interested in helping to make an Arduino Due which uses a 100-pin STM32F072?

Post by lkcl » Thu Sep 28, 2017 8:25 am

RogerClark wrote:
Thu Sep 28, 2017 6:31 am
Welcome...
thanks roger
I'm curious why you chose the STM32F072?
as i've used it before and found it to be really good. other than that... as you can see below i clearly haven't done full research yet :)
Is this based on the cost of the processor.
yes pretty much! and that it is crystal-less [syncs the clock to the USB lines - love that trick]
From the specs' http://www.st.com/content/st_com/en/pro ... 072c8.html

Its RAM is only 16K, which is less even than the $2 BluePill boards. (STM32F103C8)
*deep breath*.... and that's nowhere near enough :) rats. i knew i was missing something. let's investigate a bit more... look up the 100pin variant of the 103... and make sure that there's even enough NAND for the target application i want (!) which is to port the RepRapFirmware... aaaand that means the STM32F103VD which is 64k RAM and 384k flash...

http://www.st.com/content/st_com/en/pro ... 103vd.html

.... aaaand that's $3.80 in 10k volumes meaning it'll be about $5 from digikey.

nuts :)
And, as you have already pointed out its only running at 48Mhz - which is again lower than the 72Mhz of the $2 BluePill

I guess the main attraction is the number of ports, on a 100 pin package ??
for full Arduino Due compatibility it has to be minimum 100 pins, yes. otherwise you simply can't populate all the pin headers, which defeats the object of the exercise.
Most people seem to like using the BluePill as its cheap and powerful.
looks like a good compromise, i have a thing for the STM32F072 64-pin variant.
Or if they want more CPU performance people are using the F407, as it also has more RAM more Flash and more GPIO
(Well more of everything really)
The cost of the "Black" F407 boards is around $12 from AliExpress.
yyehhh.... you see... an Arduino ATMEGA 2560 is around half that from the Huaqiang Road markets in nearby Shenzhen (i'm staying in Taiwan at the moment). i kinda have... an... objection to paying double for something :) btw Aliexpress sellers typically charge a *lot* more... because they know you're from the West...

the thing is, even Arduino Due (ATSAM3X8E) boards are $USD 16 from factories in Shenzhen, which is a huge jump up from the ATMEGA 2560.

something _has_ to be available in the ST range which has say 384k Flash, 64k RAM and 100 pins that isn't close to $4 or above just for the processor.

will take a look at the F407. i suspect that there's an extremely common STM32 processor that's used in Shenzhen which is ridiculously-lower-priced. i found the STM32F103RBT6 was only about $1.20 in shenzhen, five years ago for example.

thank you roger for prompting me to investigate.

lkcl
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Re: Is anyone interested in helping to make an Arduino Due which uses a 100-pin STM32F072?

Post by lkcl » Thu Sep 28, 2017 8:47 am

edogaldo wrote:
Thu Sep 28, 2017 7:23 am
I do agree with Roger, I don't think I could be interested in a lower value board just because it has a Due form factor.
Tip: why not thinking of a Due adapter for the existing and cheap F103/407 V/Z development boards?
There are some which are pretty popular..
it's a nice thought... except the Due has some quite beefy power provision (an 800mA 3.3v on-board regulator, DC power in from 7 to 12v, on-board 5V power regulator) which people will be relying on. if i have to make sure that's available, then looking at the example aliexpress board which uses the STM32F407VET6 (which is over $5!!) i might as well put that on.

plus, there is the issue of space. the Due has an SPI header which comes out right smack in the middle of the PCB (which is only... i think... 3.5in x 2.5 or thereabouts). fitting that adapter-STM32F407VET6 onto a converter board... it would have to be on the back, in order for shields to fit. actually it'd probably have to be on the back anyway.

if i am to design a board, all-round i'd just prefer to design one that has the processor on it.

so. under $4. 100 pins. 384k flash. 64k RAM. USB, CAN, PWM, ADC, DAC, SPI, I2C, UART... STM32F103VDT6 looks good! 72mhz as well.

http://www.st.com/content/st_com/en/pro ... 103vd.html

let's just verify that against the ATSAM3X8E...

http://eu.mouser.com/Semiconductors/Emb ... =ATSAM3X8E

*deep breath*.... and i'm an idiot. that's a 144-pin not a 100-pin, face-palm moment :) it's also $EUR 6.75 in 1k volumes...

soo start again. under $4. *144* pins.... and there's the STM32F103ZDT6 which is $4.18 in 10k volumes. Mouser has it down at $EUR 5.37 in 1k volumes... which starts to push the limit a bit, and undermines the exercise... hmmm...

there must be *something* out there which fits...

lkcl
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Re: Is anyone interested in helping to make an Arduino Due which uses a 100-pin STM32F072?

Post by lkcl » Thu Sep 28, 2017 8:56 am

ah ha! ST32F302ZD. 144 pin, $3.80 in 10k, 384k NAND, 64k RAM, USB, SPI, I2C, CAN, PWM, ADC, DAC... looks perfect on an initial cursory examination of the specs...

http://www.st.com/content/st_com/en/pro ... 302zd.html

very very curious, why is this processor less money than the same 144-pin variant of the 103 when it's supposed to be "better" (higher performance)? that always made me puzzled....

edogaldo
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Re: Is anyone interested in helping to make an Arduino Due which uses a 100-pin STM32F072 (or something else more suitab

Post by edogaldo » Thu Sep 28, 2017 9:19 am

What could be the target price for this board?
Consider that on ebay you can buy chinese Due clones (with original SAM3X8E, MEGA16U2, etc) for 13$ each which grants you real full compatibility if you really need a Due board.

david.prentice
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Re: Is anyone interested in helping to make an Arduino Due which uses a 100-pin STM32F072?

Post by david.prentice » Thu Sep 28, 2017 9:26 am

The F103 is a fairly elderly M3 chip. Its only redeeming feature is that Chinese BluePills and MapleMinis are very cheap.
It has been succeeded by much better M3 and M4 chips

If you want a Due replacement, you would be looking at a Cortex-M3 or M4 chip with similar number of pins to the elderly SAM3X M3 chip that is used in the Due.

The STM32L4xx series would seem the obvious choice. They can run fast when required and consume low power if necessary. As well as having large memory and good peripherals.

The F072 is a M0 chip with performance not much better than an AVR. Hardly a design for the future.

Having selected a suitable MCU, you want to think about which pins to route to the Digital and Analog headers.
IMHO, the Mega2560 assignments were crazy. Not a single XCKn pin is accessible for any of the four USARTs.
And the Due assignments are not very compatible with legacy MEGA headers.

If you address these design issues, it could be a viable project. If successful, it will be cloned by Chinese manufacturers.
You will receive nothing for your time and effort. The world gets cheap hardware. Much like the enthusiasm for BluePill.

David.

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ahull
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Re: Is anyone interested in helping to make an Arduino Due which uses a 100-pin STM32F072?

Post by ahull » Thu Sep 28, 2017 11:57 am

lkcl wrote:
Thu Sep 28, 2017 8:56 am
ah ha! ST32F302ZD. 144 pin, $3.80 in 10k, 384k NAND, 64k RAM, USB, SPI, I2C, CAN, PWM, ADC, DAC... looks perfect on an initial cursory examination of the specs...

http://www.st.com/content/st_com/en/pro ... 302zd.html

very very curious, why is this processor less money than the same 144-pin variant of the 103 when it's supposed to be "better" (higher performance)? that always made me puzzled....
Also
...
ARM Cortex-M4 core with DSP and FPU
...
12-channel DMA controller
Two ADCs 0.20 μs (up to 18 channels) with selectable resolution of 12/10/8/6 bits, 0 to 3.6 V conversion range, separate analog supply from 2.0 to 3.6 V
One 12-bit DAC channels with analog supply from 2.4 to 3.6 V
Four ultra-fast rail-to-rail analog comparators with analog supply from 2.0 to 3.6 V
Two operational amplifiers that can be used in PGA mode, all terminals accessible with analog supply from 2.4 to 3.6 V
Up to 24 capacitive sensing channels supporting touchkey, linear and rotary touch sensors
Up to 11 timers:
...
One 32-bit timer and two 16-bit timers with up to four IC/OC/PWM or pulse counter and quadrature (incremental) encoder input
One 16-bit 6-channel advanced-control timers, with up to six PWM channels, deadtime generation and emergency stop
One 16-bit timer with two IC/OCs, one OCN/PWM, deadtime generation and emergency stop
Two 16-bit timers with IC/OC/OCN/PWM, deadtime generation and emergency stop
Two watchdog timers (independent, window)
One SysTick timer: 24-bit downcounter
One 16-bit basic timers to drive the DAC
...
Calendar RTC with Alarm, periodic wakeup from Stop/Standby
...
.. so all the STM32F302ZD is all round, a much better faster, more capable chip with loads more potential.
- Andy Hull -

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