Pinoccio with a Solar Panel

marekpetrik 2014-09-08 03:27:25 UTC #1

Is there any way to stop the pinoccio from rebooting when it loses USB power? I am trying to use it with a solar panel, but I get frequent reboots.

marekpetrik 2014-09-08 13:18:46 UTC #2

Putting a large capacitor (47 \mu F) between the RST and GND pins seems to do the trick.

jingman 2014-09-08 16:17:05 UTC #3

Good to know! I was wondering about this myself - thanks for the tip on a fix.

Matthijs 2014-09-08 23:25:27 UTC #4

Hmm, interesting to know. I suspected that pulling the USB plug would interrupt the VCC line for too long, but apparently the problem is that the capacitor between RESET and DTR (and also pulled down to GND) is empty (DTR is normally high, but gets disconnected when the USB power is removed), causing RESET to be pulled to GND while the capacitor charges. Adding the capacitor you mentioned should help here, though it might also prevent uploads from working (not 100% sure though).

miotang 2014-09-11 11:45:18 UTC #5

Hi,

Is it possible to have the schema of your solar panel solution ?

Thank

Mio

miotang 2014-09-16 13:59:43 UTC #6

Is it possible to have the schema of your solar panel solution ?

marekpetrik 2014-09-24 01:45:51 UTC #7

There is really no schema to talk about. I simply connected the positive lead of the capacitor to RST and the negative one to GND.

I have tried capacitors as low as 100nF. Lower capacitance did not prevent resets, but 100nF seems to work fine. Right now, I have been running my Scout off a solar panel for almost 40 hours without reboots.

miotang 2014-09-24 17:58:03 UTC #8

Thank you.

Wich model of solar panel are you using ?

wminarik 2014-10-14 16:05:35 UTC #9

Here's one option for connecting a solar panel to Pinoccio. I used an Adafruit solar LiPo charger. This board has a 'Load' output, but since it could be anywhere from 6V (the maximum of the panel I'm using) to 3.1 V (the low voltage LiPo battery cutoff), it can't be connected directly to the VUSB input of Pinoccio.

The charger's 'Battery' outputs 3.1-4.2 V and so can be connected to Pinoccio's VBAT, but requires an adapter cable. Pinoccio uses a JST-SFH connector for the battery, while the solar LiPo charger and many LiPo batteries use the JST-PH connectors (a link to sourcing the JST-SFH connects is on the topic http://discuss.pinocc.io/t/recommendation-for-battery-socket/81). I soldered up a Y-cable to attach both the Pinoccio and a LiPo battery to the charger board. A separate adapter cable converts JST-SFH to JST-PH so that I can use the default Pinoccio battery if I wish.

The JST-SFH sockets seem to only be available as surface mount parts. The leads can be carefully bent up in order to solder wires to them; bending more than about 45° risks breaking the lead. On my adapter cable I added an extra outer shrink-wrap layer for strength; hot-glue could be used as well.

The maximum output of the LiPo charger is set to 500 mA (this can be changed), but the panel can only output a maximum of ~330 mA in bright sun, so it's safe for the Pinoccio battery or a larger one. Note that the Adafruit 2W solar panel requires a barrel jack adapter to plug into the charger jack. A larger battery will allow continuous operation during a string of cloudy winter days.

This modification bypasses Pinoccio's onboard LiPo charging chip, but I think that the MAX17048 will still read accurately since it uses battery voltage.

wminarik 2014-10-14 16:51:14 UTC #10

… and a few photos of the modification:
1) The JST-SFH socket leads bent up and soldered before insulated with heat shrink:

2) The adapter cables:

3) Solar charging a Scout using the standard LiPo battery:

4) Solar charging a Scout using a larger external LiPo battery:

Eric 2014-10-14 19:10:45 UTC #11

This is amazing! Excellent writeup too!

Yep, wished there was an SFH through-hole version, but alas only surfacemount. This might be a really great candidate for a breakout board project on OSHPark.

Very cool stuff! Thanks for sharing.

miotang 2014-10-15 01:22:55 UTC #12

Wow !!!

It will be great for our project... We need infinity power.

Thank's again

Matthijs 2014-10-15 13:23:24 UTC #13

Awesome project.

Thinking on it, could you not just have used the VBAT pin on the Scout? If I'm reading the schematic right, it's directly connected to the battery. Alternatively, there's two holes under the SFH socket that connect to the battery too.

wminarik 2014-10-15 15:23:11 UTC #14

Thank you all for the support.

The VBAT pin on the header would work, but I'd still need a Y-cable to connect both an external LiPo battery and the Scout to the charger board. Using VBAT would complicate the use of backpack boards, and would tie up the GND pin too. VBAT is also useful as an output for powering higher current devices (motors, etc.).

I expect that the upcoming Solar Energy Harvester backpack, or an equivalent backpack with a battery socket will be a more elegant solution.

I also thought about soldering a JST-PH socket directly to the two holes under the current battery socket. Unfortunately, the JST-PH has a 2mm pin spacing (the holes are spaced 0.1"/ 2.54 mm) and the extra socket would interfere with the regular battery arrangement.

bitcoinsdk 2014-10-21 15:28:33 UTC #15

Very nice! @wminarik Do you offer help with projects? Would love to chat. Please contact me shawn at fuzionshares dot org

alexglow 2014-10-21 18:05:06 UTC #16

Awesome tutorial, @wminarik! I've featured it in our Projects section with a link back here; please feel free to claim it and edit if you see fit.

So cool to see solar power implemented before we even get the backpack out!

miotang 2015-02-06 22:43:41 UTC #17

Hi,

I'm looking for JST-SFH connector and I didn't find IT anywhere....

Do you know where I can buy it ?

Tank's

Mario

Matthijs 2015-02-09 18:34:34 UTC #18

@miotang, see http://discuss.pinocc.io/t/recommendation-for-battery-socket/81/2?u=matthijs

Kurdman 2015-02-11 08:02:45 UTC #19

Thanks a stack (South African for a great deal,,) for the share. I will definitely try this out