LiPower Sheild?

[yukivx]

I'm not familiar with Digispark. Therefore I try various studies now.

Probably Digispark works alone if there is a power supply. If Digispark can easily work with LiPo battery like LilyPad LiPower, I'm glad. It is because LiPo cells is very small. It's nice if Digispark uses the LiPower Sheild and allows you to charge 3.7V LiPo cells.

LilyPad LiPower
https://www.sparkfun.com/products/11260

LiPo charger
https://www.sparkfun.com/products/11231
http://www.seeedstudio.com/depot/lipo-rider-p-710.html

Polymer Lithium Ion Battery - 110mAh (Weight: 2.65g)
https://www.sparkfun.com/products/731

[MichaelMeissner]

The digispark runs at 5v.  In theory, if you use the boost shield, it should allow you to connect a 3.7v battery, but be sure to check with others about the specs of the boost shield.

[sparr]

One LiPo battery on a boost shield is an efficient but more complex option. Two LiPo batteries in series can use the onboard regulator directly.

[yukivx]

Thank you sparr and MichaelMeissner,

I was able to understand it as a more complex options. I will buy two LiPo.

[Bluebie]

Speaking speculatively, the microprocessor used in the DigiSpark can run on as little as 2.7 volts, and can easily be powered by a lipo battery or even a lithium button battery.  This is complicated a little by the clock speed, but if you set the OSCAL register to a lower value as soon as your program begins, it\'ll only be running out of spec for the duration of the bootloader. This leaves only one further potential complication - if the digispark team enable the brown-out detector, it might not work at these lower voltages. Hopefully if they do enable brown-out detection, they\'ll set it to 2.7v, though I\'d rather see brown out detection disabled entirely as it consumes a small amount of power when the device is asleep, shortening it\'s sleeping battery life - we\'ll see when the final devices start being delivered.

[Lami]

All that said, I would like to see LiPo charger/boost combined shield, just for simplicity. Something accepting external power (wall adapter, solar, whatever), can charge connected LiPo battery and supplies power for a digispark. One can simply clone mentioned SeedStudio\'s LiPo rider, but those less experienced (as I am) prefer to leave design job to professionals

[digistump]

@Lami - a charger/boost combo is on my to do list once we ship the kickstarter rewards

[ChrisMouse]

This item should work well to power a Digispark from a LiPo battery.
https://www.sparkfun.com/products/11260

[Crump]

I\'ve been taking a stab at designing this but short of having a jumper or switch for changing from battery to charging I don\'t see a good way (read: simple enough to fit it all in the space of a normal shield) to both power/boast from the lipo to the 5v pin then also let the 5v pin charge when the DigiSpark is plugged in to USB power.

If you think it would be ok to put a switch on there and trust the user to change it before plugging it in. Then great, I have the design done

Now a using a small switch, so we wouldn\'t have to remove the batteries all the time may be a good thing. Lord knows the jst connectors are PitA! So maybe it just is called the power/charge switch and we put some kind of reverse bias on the boaster and also make it trigger the EN of the boaster to low... that way it wouldn\'t break things if you forgot to flip the switch and wouldn\'t drain the battery... but it also wouldn\'t charge it till you did.

SO does anyone with better knowledge of this sort of circuit design know of a good way to both power and charge on the same pin? we need a fancy gate keeper.

[jmcmahon443]

@Crump


This is the problem I want to solve as well. I will let you know of anything I learn!

[defragster]

I got a PRO reward LiPo unit yesterday and today it is working.

I'll look to post this in a current place - but my search landed me here so far and thought it might be of interest.