Amazing new board running Espruino

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  • "Shrimping"? "shrimping" sounds like a euphemism for some deviant sex act, not something to do with electronics... I've never heard it called that. Also, that page implies that the decoupling caps are optional on AVRs. They are not, and boards that omit them will suffer from unpredictable instability, particularly while programming the chip.

    I've more often seen "shrinkify" for moving devices down onto smaller boards (smaller boards and smaller chips, ie, ATTiny)...

    I'm not really sure what people would shrink to though - you can make something a little cheaper than the pico, but not by much, unless you've got @Gordon's ST connections. The STM32F401 that the Pico uses is like $8 from digikey, and other STM32 chips are in the same ballpark, and since you need your own board made too... It's certainly not like on Arduino, where you can replace a $30 uno with a $2.25 pro mini knockoff or $4 breadboarduino. And there ain't no way you're going to get something physically smaller than the pico!

  • It's not the shrinking... it's a motaphorically for minimalist (also smimplified) - the poor tinkerer's version. It's not a size thing at all... because the small breadboards have about the same footprint as an arduino (uno).

    The challenge with the cheap STM32 boards is the fact that they are STM sponsored/marketing tools to the get develpers - and tinkerers - used to the hardware when on low budget - usually in schoool or while in school in their hobby time - and later, when in real business/workplace, will pick what they have experience with - and finally can materialize their dreams in real setting with elaborate boards. And with the fineprint that does not allow to use such boards as components in a product... a limitation which Espruino does not have - by 'overall design'.

  • Yeah - the cheapest option seems to be a Nucleo board. On that topic, I should be getting some Nucleo-to-sane-pinout (grouped by port, in numeric order, labeled) adapter boards this week. Assuming I didn't botch it, I'll put em up for sale on Tindie - I can't be the only one who can't stand the un-labeled, randomly distributed pinout.

    It's worth noting that in Arduino-land, you can get a pro mini with free shipping from china for like $2.25, which is about what you'd pay for the bare chip. So, so the breadboarduino is not a poor mans option in arduino-land either.

  • I met someone at a UK maker faire that was pushing 'shrimping' - ( I think). I guess the name is supposed to seem more friendly, but it does sound kind of odd :)

    Due to a really shitty decision by UK education authorities, for some electronics projects in school kids absolutely have to use bare chips (no modules allowed), so they're actually very limited with what they can do.

    I think it probably 'feels' better using the bare chips - although I agree about the costs of the Chinese clones. I had to buy the chips for this new batch of Picos, but buying in quantity in China makes a massive difference - I can buy them for at least 1/4 of the price you'd pay if you went to DigiKey or somewhere. I'd be pretty sure that trying to make your own Pico will end up costing you more than the $25 they sell for.

    It's just a shame ST don't do DIP packaged STM32s - they'd be significantly more interesting with Espruino on them :)


    You know those boards have Nucleo.D0/A0/etc defined? Could make your life a bit less tedious :)

  • @allObjects yeah, the whole point was to get that experience, to get a feel for what I was working with.

    Assembling my own boards does turn out a bit cheaper than the pico. Here's a quick breakdown:
    $2.80 - STM32F401RCT6 (lower spec than the pico, but I managed to get some heavily discounted)
    $1.50 - pcb (small run, gets a lot cheaper in large quantities)
    $1.50 - connectors/headers
    $1.00 - regulator
    $2.50 - crystal
    $4.00 - other components

    So it is costing me ~$14 per board when buying parts for 15 to 20 boards at the moment. Getting the STM32's that cheap was a one-off, and because they're lower spec than the pico's means that it'd cost closer to $20 each, ignoring setup costs, accidents and prototyping. Considering assembly, handling, and distributor costs, I'm pretty impressed at the pico's price!

  • Man, I'm clearly getting chips from the wrong place.

  • $8 is about right for individual stm32f4 chips. If you jump onto octopart and get them in some sort of quantity, they go down to $4-$5 (below $4 for bulk). If you find someone trying to dump the last 18 of them that they have in stock, below $4 is possible. :P

  • Btw, something that isn't covered in my cost breakdown is assembly by hand. It takes ages. Economically, I'd definitely be better off grabbing a heap of picos. I'm making my own boards for the form factor, getting the functionality just how I want it, and for fun!

  • Man, I'm clearly getting chips from the wrong place.

    I know, that was really good value! But yes, it's the fun of doing it yourself :)

  • An updated version of my board, using cheaper crystals, usb mini (much sturdier), no more 1.27mm headers and hopefully better trace routing for decoupling (although I have no idea how to check or if I'll ever care). Unfortunately all the silkscreen labels didn't make it onto the board, not sure if they were too small or overlapping parts. Soldering the mcu is getting much easier with practice, it's actually a bit easier than doing all the capacitors! Now I'm just waiting for some daughter boards to be fabricated: a neopixel backpack, a 2x mosfet output, an adjustable boost regulator and one that has a temperature sensor, voltage divider, led and button.

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  • Wow, that looks like a really tidy little board now :)

  • Thanks! Espruino is really what got me to jump from doing these with a Atmega328. Being able to plug in and start talking to sensors using a console interface (plus javascript!) really made prototyping a blast.

    Thanks for the suggestion of the usb dfu bootloader, I gave it a go this time and it worked great.

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Amazing new board running Espruino

Posted by Avatar for the1laz @the1laz