Our New KickStarter! Espruino Pico

It's just launched, and it's awesome!

https://www.kickstarter.com/projects/gfw/espruino-pico-javascript-on-a-usb-stick

Please think about supporting me - the one's really cool, and I'd love to see it succeed!

Hurray - that new prototype looks really good. Got any pictures of the underside of it?

The bit about the 10 year runtime on an AA-sized lithium - might want to clarify that. Most people will assume that means " Lithium", the 1.5v alkaline replacements, not the 3.6v lithium thionyl chloride cells that I assume you had in mind.

Looks really cool - looking forward for mine to arrive in April!

I liked some of the ideas (the use of the plastic pipe & end stops was imaginative)

Have you thought of offering solderless pins?

https://www.sparkfun.com/products/10527

Thanks!

@DrAzzy - Ahh, I didn't even realise they did AA sized lithiums that weren't 3v :) I've just updated it. I've been avoiding posting pictures of the other side because the silkscreen says 'Espruino Mini' :) I can't find a picture right now, but the attached PCB image might actually be more interesting?

Basically there are no components, but there are pads for a JST connector, as well as 0.05' spaced pads for JTAG/NRST so you can use a hardware debugger on it with a bit of soldering.

@DaveNI - I did look at solderless pins (I ordered some, there's a post on it somewhere), but they're actually really hard to push in. So much so that if you're not careful you could easily damage yourself/the boards. You really need a vice.

I could make the holes in the board just a tad bigger so the pins fitted better, but I asked the pin manufacturers and:

• They really weren't interested in selling me sensible quantities (not even 100,000)
  
• They said they couldn't recommend using bigger holes, and weren't really willing to make any comment on it.
  
  

It sucks really - it would have been perfect but I tried to contact 3 different manufacturers and nobody was really very interested at all.

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What would it take to enable Pico to be - reverse - sticked into a Wifi USB adapter like pictured below? (I'm sure power could be of concern: Pico saving the world, and the adapter wasting it...). These things are now dirt cheap and readily available.

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Hi Gordon,

Congrats! We will reach the 50k goal for sure. Can't wait for a real socket support.

Sacha

@Sacha, thanks!

@allObjects I think it'd require quite a lot I'm afraid (USB OTG support would have to be added, and that may need some other components to be done properly). Nice idea though! The ESP8266 is about the same price and should still fit on pretty easily though.

Hello,

The Espruino and Espruino Pico are really interesting projects. So I supported you by backing an Espruino Pico yesterday and received an Espruino 1V4 from Limetrace last Monday.

The Espruino board is the best choice when it comes to battery operated applications such as data loggers.
A proper ESP8266 module, solving the very tight power management issues, is still my best choice to IOT. A GPIO could just shut it down until sending data is a necessity... This module is a game changer and Espruino is very well suited to interconnect it with sensors!

Go on with your projects!

Congrats Gordon!

I like the new pico already.

Thanks for all the support!

Ic... (OTG). I was less thinking about price, but more of change of connectivity/connectivity
and pin reuse at the same time: not to have the USB (board) plug and chip pins sitting idling there while not plugged in (as USB slave) and not being able to use the 'pins' (chip and board)... reusing space and pins in pico context means a lot.

The bit about the 10 year runtime on an AA-sized lithium - might want
to clarify that. Most people will assume that means " Lithium", the
1.5v alkaline replacements, not the 3.6v lithium thionyl chloride cells that I assume you had in mind.

Current draw in sleep: <0.1mA - over 2.5 years on a 2500mAh battery.

Whoa ...The minimum "Pico" input is 3.5-20 vdc.

Are we talking 1 or multiple batteries?
Are you using a booster on the battery(s)?
What type of battery are you using?
Are we reducing the capacity 8% per month for self discharge? (for lipos) Varies between other battery chemistry.

Lithium Thionyl Chloride batteries are not lipo batteries. They use a different chemistry, and are not rechargable. They have (according to the manufacturers, so take w/salt) ~1% self discharge per year. They also don't handle high current very well (they're the batteries they use in, for example, those new 12-year disposable smoke detectors, that never need new batteries).

I doubt they'd actually be putting out 3.5v by the end, though they've got a pretty flat discharge curve, and I think they'd be close enough that it'd still work. The STM32F401CC is spec'ed to run at 1.8-3.6v, it looks like.

On another topic... shouldn't one of the kits include an esp8266? That'd be a great selling point, Wi-Fi connectivity included in the kit

Thanks @DrAzzy - it seems some people are taking real issue with the 10 year figure, but just to show my calculations:

• 2.5Ah@3.6v is standard for these batteries
  
• STM32 is 12uA in sleep (datasheet says as low as 10uA, but let's be careful :)
  
• XC6206 regulator is 1uA
  
• Waking every 60s for 10ms is 30mA*0.010s / 60 = 5 uA average
  
• So 18uA average
  
  

That's 2500mAh / 0.018mA = 138888 hours = 15.8 years

So quoting 10 years leaves 5.8 for self-discharge/etc :)

I was very tempted by adding ESP8266 to a kit... I may add it later - I just want to get it working first and to make sure that it's properly reliable :)

Gordon, 10 years lifetime of a battery means you lost 33% due to self-discharge after 10 years @ 25 C. So after 10 years you only have 0.66 * 2500 = 1650mAh. So 10 years working is not a problem.

BUT: If your continues current drain is larger than your self-discharge you can ignore your self-discharge current. Self-discharge current is simply the result of a chemical reaction always taking place even if there is no load . If you do have a load current that is larger the self-discharge effect is much smaller than if you have no load at all.

Paul.

The Pico is awesome!

Little questions:

I just noticed the line about the onboard FET - Is this connected to one of the pins? Which one? What type of FET?

What're the two pads right next to the resonator (or crystal?) for?

What's it clocked at? 84mhz I'm guessing from the datasheet?

Hey, have you thought of using the newer 411? It is a bit more efficient and fits in the same footprint.

@DrAzzy the FET is the same FET that's used for battery switching (I think it's connected to B0 right now, but that might change). The idea is if you're plugged into USB then you can use that same FET to get a powered output. It only pulls up to VUSB, but it's still pretty handy.

The pads next to the resonator can take a 32kHz crystal - I was considering pre-installing them, but they're surprisingly expensive when that size (way more than the resonator) and I'm not sure it'll be that useful - The F4 can do RC calibration against the high speed oscillator, so for most things it'll be more than accurate enough. And yes, 84Mhz. I got the impression that you can overclock it to 168Mhz (like other F4 parts) but that's not really a priority right now :)

@FyberChris the 411 looks interesting - I hadn't considered it before. To be honest the 401 is still pretty good for power usage when in sleep mode. The only UFPQFN48 right now seems to be the STM32F411CE though, and that's basically 2x the price :(

Well done on getting it funded :-)

The pads next to the resonator can take a 32kHz crystal - I was considering pre-installing them, but they're surprisingly expensive when that size (way more than the resonator) and I'm not sure it'll be that useful

Wow, yeah, crystal prices go way up when you want them tiny like that. If people are going to be soldering them on at home, wouldn't we likely be using a radial can type, like we do now on the Espruino1v3, not the miniscule SMD ones? It looks like there's plenty of room to bend it over the resonator. In that case, why not leave holes for a radial can type, instead of SMD pads?

Just a thought, if the only item on the back of the board is a connector for external power why not replace this with a micro SD card connector like this http://uk.mouser.com/ProductDetail/Hirose-Connector/DM3D-SF Then you would have the same functionality as the current Espruino. If people needed external power they could use the USB connector and a power injector something like this http://linitx.com/product/5v-power-injector-for-usb-on-rb411uahr-and-rb493g/12849

How often do you think the external power connector would be used?

"What would it take to enable Pico to be - reverse - sticked into a Wifi USB adapter like pictured below?"

The problem with these types of module is they offload a lot of processing to the host PC I understand. OK for a PC to handle no so much for an Espruino.

Congratulations on funding. I got some samples from my rep. I was originally worried it was a replacement, but ST is planning to keep both lines. Honestly, I am not sure which to finalize design on either. I think both are going to require factory orders as neither seems popular enough at the moment for distributors to keep on hand. Arrow has been really good to me with their quotes, but it may be the specific Seattle sales office.

why not leave holes for a radial can type, instead of SMD pads?

I'll have a look at that - routing is a bit tight so I'm using SMD wherever possible - but IIRC there may be some free space around there.

SD card

I think the battery is more useful than the SD card - most switchmodes in USB power packs aren't that efficient (designed for 1-2A loads) and will kill the battery life. Also when you do that you have to disconnect the device from power in order to power it from a battery - it's nice (especially with the RTC) to be able to keep it running.

Also I'm not convinced there's space for a micro SD card. I may do a plug-in board with one on, but I'm not sure you can get a connector on without the micro SD interfering with the soldered-on pins.

@FyberChris I've been talking to ST, and they seem pretty happy to do a deal on the F401CD for me - so that really narrows it down. Hopefully I'll announce it on the KickStarter soon. Also I have the 401 working fine, but I saw someone trying to get the 411 working with Espruino last week and he wasn't having much luck (I think support only got added via the new STM32 cube stuff).