Sunny Vario

Solar powered audio only variometer using MSP430 and MS5611

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Simple solar powered audio only variometer using MSP430G2 and MS5611. Based on the earlier schematic by Hari Nair ( Layout uses SMD parts and pads that can be soldered by hand.

The design was formatted in a 1" square to enter it in the square inch project competition.

This solar powered vario for paragliding is an adapted from the design by Hari Nair. It includes his original solar charging of a super capacitor, with an updated pressure sensor and a microprocessor selected with the minimal pins and memory needed for the design. In addition, the USB charging circuit was removed, but can be added using the spare solar panel connector.

The original design by Hari Nair used two 6V 16 mA solar panels. There is provision on the PCB to connect two, but I am using a single slightly larger 5.5V solar panel instead. This reduces the total charge on the capacitor, but gives a slightly larger headroom to prevent over charging of the capacitor by the solar panel. The diode D1 drops the voltage by approx 0.6V or less at low current which makes it a bit to close to the capacitor voltage rating if using 6V solar panels.

The super capacitor will fit any 5mm lead spacing package. The size of 0.22F was selected to give a run time of around 15 minutes without solar access. A larger capacitor can be used if you spend a lot of time in the shade at cloud base. But only testing will confirm if the selected capacitor is sufficient for real flight. The 0.22F capacitor greatly reduces the part cost over larger sizes. Maxim has a good tool for calculating run times from capacitors (

  • 1 × MSP430G2553IPW20R Microprocessors, Microcontrollers, DSPs / ARM, RISC-Based Microcontrollers
  • 1 × MS5611-01BA03 Pressure sensor
  • 1 × LP2985-25 Power Management ICs / Linear Voltage Regulators and LDOs
  • 1 × 0.22 uF 5.5 V super capacitor
  • 2 × BLM18AG601SN1D 0605 EMI-RFI Suppression and Shielding / Ferrites

View all 16 components

  • Board assembled

    Alex12/22/2015 at 08:30 0 comments

    I assembled the first version of this board. The solar charge works already and the board powers up. Still working on the firmware. Setting the pin registers in the msp430 is painfully slow and time is scarce in the lead up to Xmas.

    No problem on the vario volume tho, I tested it at 3V and it was too loud (on shoulder strap), louder than my full size digifly vario.

  • Schematics added

    Alex12/02/2015 at 01:58 0 comments

    Adding the schematics, BOM and design files for the one square inch project deadline. I wanted to wait until I tested the boards before uploading them here. But as this is what i have sent to manufacture i will upload it as is. You can find a pdf version on the git repo I just created for the project Suny_Vario.

  • Time to start building

    Alex11/24/2015 at 06:14 0 comments

    The PCBs have arrived from I am very happy with the isolation around the pins on the MSP430. Time to put the parts on. As always there are obvious improvements in the silkscreen that I will make for the next version. I better get cracking on the firmware.

View all 3 project logs

Enjoy this project?



alpha_ninja wrote 12/21/2015 at 07:55 point

Please make sure to upload photographic or video proof of this project's PCBs working by the next deadline (in about two days!)

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Alex wrote 12/22/2015 at 08:36 point

I posted my progress to date. Not sure if this is enough to keep me in the running?

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alpha_ninja wrote 12/22/2015 at 17:59 point

You should be fine :)

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Blecky wrote 12/08/2015 at 03:31 point

[verified: no design files missing]

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Blecky wrote 12/07/2015 at 01:44 point

Just a friendly reminder to please upload your complete design documents by 23:59 UTC on Dec 8, 2015 to be in the running for #The Square Inch Project! (You seem to be missing your drill files).

  Are you sure? yes | no

Alex wrote 12/08/2015 at 03:27 point

The drill file is formatted for OSHpark. It can be found in the git as Sunny_Vario/Version1.0/kicadSolarVario/gerbers/solarVario.xln or in the zip file in the gerbers folder that can be uploaded straight to OSHpark. You can rename it whatever extension the board shop wants.

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Blecky wrote 12/08/2015 at 03:30 point

Ah I see them!

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alpha_ninja wrote 12/02/2015 at 00:42 point

This is your one-week reminder to upload design documents:

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Timothée wrote 11/24/2015 at 09:02 point

Just to save you some time, I made such software opensource:

For a commercial product:

With exactly the same CPU  and sensor.

May I suggest you that direct driving of the piezzo will be to weak; you need much  higher voltage that 3.3V to drive a piezzo.

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Alex wrote 11/24/2015 at 20:17 point

Thanks Timothee, That is a nice looking vario. Hari has also made his firmware available so I am working from that. I will have a read of your firmware to hunt for any improvements.

Re the piezo volume, this vario is running at 2.5V, but the piezo is driven in a push/pull arrangement giving a much higher volume than otherwise and avoiding the need for higher voltages or extra parts. There is a good explination in the link above.

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