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alsenin

$4.99 Stellaris (Cortex-M4) LaunchPad

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FYI: Some kind of self-promotion ;)

I modified my stellaris Launchpad to work with a single-cell LiPo battery.

Turned out that there is some kind of research involved, instead of just plugging it in.

http://blog.psten.de/post/fuel-for-the-stellaris-rocket

title.JPG?dl=1

 

Nice find. Note though, even though the regulator is a good ldo (<0.1v dropped, 0.15 at high current spikes), it isn't a boost converter. Minimum V-in is Vout+Vdo, so 3.3v + 0.1v. If your lipo goes below 3.4 to 3.3v, the regulator will go in a passthrough mode. Lower than 3.3v and it will possibly damage the regulator though, so a voltage monitor (hell, the stellaris chip can do that) tied to the regulators enable line would be nice.

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A voltage monitor is definetly the right way to go, even though the voltage regulAtor won't be damaged by undervoltage.

It operates down to a Vin of 1.7 V, and its Input range is -0.5V - 5.5V.

But i don't know how the M4 reacts to voltages below 3V :D

My Launchpad Lready did run low on batterys, discharging the lipo below 3V and it stopped working, but Fter a recharge everything is working fine again.

For reference: http://www.ti.com/lit/ds/sbvs038t/sbvs038t.pdf

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FYI: Some kind of self-promotion ;)

I modified my stellaris Launchpad to work with a single-cell LiPo battery.

Turned out that there is some kind of research involved, instead of just plugging it in.

http://blog.psten.de/post/fuel-for-the-stellaris-rocket

title.JPG?dl=1

 

Blue, could you please cross-post this to Stellarisiti. Thanks!

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A voltage monitor is definetly the right way to go, even though the voltage regulAtor won't be damaged by undervoltage.

It operates down to a Vin of 1.7 V, and its Input range is -0.5V - 5.5V.

But i don't know how the M4 reacts to voltages below 3V :D

My Launchpad Lready did run low on batterys, discharging the lipo below 3V and it stopped working, but Fter a recharge everything is working fine again.

For reference: http://www.ti.com/lit/ds/sbvs038t/sbvs038t.pdf

 

Oh, and besides the rgb light not working well (it's powered off vbus, not 3.3v), the extended boosterpack connector j3/j4 also runs off vbus, so any stellaris specific boosterpack might not work properly due to the lower voltage.

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You're totally right about the boosterpack connectors J3 and J4, i forgot to mention this in my post. Although it is called '+VBUS' and not '5V', most boosterpacks with the XL pinout would expect 5V on +VBUS and therefore might not work with this hack if they make use of the 5V ;)

The RGB led however runs happily on a lipo. When it goes dark you propably should recharge the lipo preventing it from undervoltage.

I did not measure the minimum voltage for the led, but I can do some more 'research' on that if you're interested :)

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Boo! They upped the price to 12.99. Glad I ordered an extra 2 a couple of weeks ago - even though they won't ship until December.

 

I did the exact same thing. Ordered 2 extra once I received my first two. I'm happy I did that.

12.99 still isn't bad, but I'd think twice before ordering extra.

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Yeah - below $10 is really my threshold for things I'll order without hesitation. Honestly though - I don't expect to do a ton of projects with it - just bigger projects that require better hardware - I'll probably continue to use my 430's for most of my projects.

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