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

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RogerClark
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Re: Is anyone interested in helping to make an Arduino Due which uses a 144-pin STM32F072 (or something else more suitab

Post by RogerClark » Sat Sep 30, 2017 6:03 am

@lkcl

FYI. I've abandoned trying to shoehorn a F4xx onto the Blue Pill form factor.

Its basically uneconomic and inpractical for a number of reasons.

Anyway. Good luck with your board. At least you have more space and won't need to resorting to 4 layer boards and exotic device packages in attempt to squeeze them in a 0.5 inch (12.5mm) wide space

lkcl
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Re: Is anyone interested in helping to make an Arduino Due which uses a 144-pin STM32F072 (or something else more suitab

Post by lkcl » Sat Sep 30, 2017 7:06 am

ChrisMicro wrote:
Sat Sep 30, 2017 3:46 am
Just throwing in another thought:
I found it quite useful to have an micro-sd-card-connector directly on the board ( like on the F407black or some discovery boards ).
This could be another benefit of the F4-Due.
But I don't know how this would increase the cost or if even there is some space on the board for this.
Of course the most important of the project: maximum pin compatibility to the Due and minimum software setup problems.
yehyeh, i found there's a library (board variant) which already exists, which is neat.

yehh i've been exploring the 2560 and the due, and it's fascinating: the mega2560 is amazingly clean. tracks come out dead-straight, go directly to the pins. the whole arduino board layout - headers particularly - was definitely definitely designed specifically with the 2560 in mind.

consequently, the due layout is a mess. they had to go to 0402 components to get them all on (power, the extra management micro-controller) but even the routing has to criss-cross underneath the processor, whereas for the 2560 it just goes pretty much straight out directly to the pins.

the stl47no is looking the same way: i've done my best to get the pinouts as close as possible but it's the variety of functions that make that really hard.

about the on-board micro-sd card idea: i really like it! except.... i used the 100-pin variant not the 144-pin one and it would be a complete from-scratch redesign! whoops... :)

so, thinking it through: they didn't put a microsd card slot on the 2560 because pretty much every pin bar 5 is used, plus the idea of the product is that you buy shields... therefore it has to stay as generic as possible. the due, they simply... ran out of space. i'm kiinda wavering in a nebulous way to sticking with the original principle: keep the board generic. that way, if someone wants to connect an eMMC chip or a full-sized SDCard "shield", they can. really nice idea though.

lkcl
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Re: Is anyone interested in helping to make an Arduino Due which uses a 144-pin STM32F072 (or something else more suitab

Post by lkcl » Sat Sep 30, 2017 7:08 am

RogerClark wrote:
Fri Sep 29, 2017 8:30 pm
lkcl wrote:
Fri Sep 29, 2017 8:16 pm
http://hands.com/~lkcl/stl47o/

git clone http://hands.com/~lkcl/stl47o/.git/ will create some sort of html page and point at a wiki at some point....
Cool..

I'm currently battling with the problem of getting a decent F4 device onto the much smaller BluePill form factor..
Not easy...
i saw... :) keeping an eye on that thread too. care to post the occasional screenshot? [edit: oh! _that_ kind of battle! aww shaame... ]

lkcl
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Re: Is anyone interested in helping to make an Arduino Due which uses a 144-pin STM32F072 (or something else more suitab

Post by lkcl » Sat Sep 30, 2017 6:46 pm

okaaaay it's official: possibly the untidiest board i've ever done. i've not done such large ICs on small 2-layer boards before: it's definitely... an acquired skill, i get that distinct impression now :)

i'm going to try for a day or so to get GND into those void areas at the middle-bottom: that's primarily the ADC tracks along the bottom. there's space to fit three 0.1uF capacitors around the 417, but that's down to good design by ST (the power and GND being on the corners).
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RogerClark
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Re: Is anyone interested in helping to make an Arduino Due which uses a 144-pin STM32F072 (or something else more suitab

Post by RogerClark » Sat Sep 30, 2017 8:18 pm

Wow, that was quick...

Which CAD system did you use?

lkcl
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Re: Is anyone interested in helping to make an Arduino Due which uses a 144-pin STM32F072 (or something else more suitab

Post by lkcl » Sun Oct 01, 2017 3:38 am

RogerClark wrote:
Sat Sep 30, 2017 8:18 pm
Wow, that was quick...
yyeahh.... i tend to just... not stop. in this case that meant working overnight. again. also, i made a deliberate decision to use the MEGA2560 reference design pretty much as-is: not even move the components that aren't necessary to move, don't add anything that isn't unnecessary - i didn't even touch the tracks as they came out of the original pin-headers unless it was absolutely necessary.

yesterday (was it yesterday? i lose track of time when focussing this hard...) i did the MCU pinouts by literally dropping the 417 as a "shadow" on top of the 2560, as a way to check what pins would best suit.

... the irony is: after connecting 25% of the pins i realised that actually the layout would be much much better if i rotated the 417 through 90 degrees... :)
Which CAD system did you use?
eagle. not my favourite. biiig climb-down from PADS. messes up my automated keyboard-and-mouse-don't-have-to-think reflexes too :) even my ability to correctly and instinctively use zoom-in and zoom-out goes out the window! with PADS it's very senslble: the mouse automatically jumps to the centre of the screen on every click. that's *incredibly* handy and highly intuitive. eagle and other f***-wit programs: you have to think, "oh f*** where the f*** should i put the f*****g mouse to get the f*****g zoom to move what i want into the centre of the f*****g picture. f***!" :) [ha! might have beaten rusty russell for "most number of swearwords on one linux kernel commit line" there....]

lkcl
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Re: Is anyone interested in helping to make an Arduino Due which uses a 144-pin STM32F072 (or something else more suitab

Post by lkcl » Sun Oct 01, 2017 3:43 am

lkcl wrote:
Sat Sep 30, 2017 7:06 am
ChrisMicro wrote:
Sat Sep 30, 2017 3:46 am
Just throwing in another thought:
I found it quite useful to have an micro-sd-card-connector directly on the board ( like on the F407black or some discovery boards ).
This could be another benefit of the F4-Due.
about the on-board micro-sd card idea: i really like it! except.... i used the 100-pin variant not the 144-pin one and it would be a complete from-scratch redesign! whoops... :)
ok so i thought it through, chris... and i think it might actually be doable, because there's 2 spare pins that i *MIGHT* be able to route without too much disruption: one can be used for CS, the other for CD.

with the fact that the CS line could be permanently disabled (off in software), functionality is not disrupted i.e. it doesn't stop the board from being "arduino-mega-compatible" because... SPI is a shared bus with individual CS lines.

the MicroSD card can sit right next to the ICSP header... which coincidentally is right where SPI is... there also happens to be a 3.3v supply... so we're good!

also... i checked: the entire left side of the board between the processor and the right-most pinheader (2x18) is entirely free of components with the exception of the RESET switch and that 6-pin ICSP (SPI) header. so... there's actually room for a MicroSD card slot, yay.

also they're only around $USD 0.30 in shenzhen so it's not going to be costly: i have another project i'm ordering 1,500 for...

... so... good call man. will let you know how it goes.

lkcl
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Re: Is anyone interested in helping to make an Arduino Due which uses a 144-pin STM32F072 (or something else more suitab

Post by lkcl » Sun Oct 01, 2017 12:47 pm

hmmm... still struggling to find a schematic for the 471 with recommendations on how to do the XTAL. am i right in thinking that the 471 has auto-synchronisation from the 32.768kHz XTAL? that would be a nice feature.

lkcl
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Re: Is anyone interested in helping to make an Arduino Due which uses a 144-pin STM32F072 (or something else more suitab

Post by lkcl » Sun Oct 01, 2017 2:36 pm

https://list.tmall.com/search_product.htm?q=ch340g+IC

https://list.tmall.com/search_product.htm?q=FT232RL+IC

yowser what a massive price-difference. $USD 0.30 for the CH340G vs nearly TWO for the FT232RL. i'm staring at a china arduino 2560 clone wondering why they use the CH340G... not any more. hmmm i wonder where i could get a full board / schematic design which contains the CH340G... oh look! https://learn.sparkfun.com/tutorials/se ... okup-guide ta-daaa, eagle files 'n'all...

lkcl
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Re: Is anyone interested in helping to make an Arduino Due which uses a 144-pin STM32F072 (or something else more suitab

Post by lkcl » Mon Oct 02, 2017 9:15 am

hiya roger i wanted to create a wiki page for the stl47o, to document the pinouts - would that be ok? (reason i ask is, there's no way to create an account named lkcl on the wiki. i assume you got fed up of harvesting spam....)

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