HW for low-power(!) ANT+ data acquisiton device

[Gábor Ziegler]

Hi all,

Do you have any concrete board + shield recommendation that can be used

1. to collect ANT sensor data,like a head unit, or sports watch does

2. which is strictly low power, i.e., suitable for battery operation, like the Adafruit Feather nRF52

3. has sufficient storage support for the collected data, say a couple of MB non-volatile memory (i.e., which holds already recorded data even in case of battery failure)

4. can connect to other Arduino sensors/shields (like GPS, like barometric altimeter,etc.)?

In other word, I would like to create a portable, battery operated ANT+ fittness sensor data acquisition device.

Thanks,

Gábor

[Curtis Malainey]

Hello Gabor,

If you are intent on staying on Arduino then probably the nRF52 feather is your best bet if you can figure out how to load the ANT Softdevice onto the chip. I actually just got my device in the mail today and hope to publish a how to eventually and then bring up the ANT native API. If that is not up your alley then you could use the ANT Featherwing but that board does not have any of the power saving features (such as the suspend pin) broken out. In theory you can always just strap a bigger battery to your project to get around these issues. Add a data logger feather board and you would be fine. That being said the ANT featherwing board and a GPS board will not work together as they both occupy the serial bus. (watch out as this bus is used by a lot of items) You can use broken out (but unlabeled and not very breadboard friendly) D52's on digikey with the ANT firmware preloaded if you want to use ANT externally.

If you want to go the extra mile I would recommend using another board such as the nRF52-DK. I have gotten the soft device running in arduino on it (about 2 years ago so I don't remember much.) The benefit being that you could run mbed (vs arduino) which has proper power management APIs. You would need to avoid powering the debugger on the board (i think you can do that) so it definitely is more complex for setup. If i remember correctly though, the board is designed to accept the arduino shield form factor (the only issue being you need to make sure your shield is 3.3v compatible.

I think you will be hard pressed to find a board with a couple MBs of spare flash onboard. The alternative is you could use a flash chip if you don't want to step it up all the way to a SD card reader.

So I guess what I am saying is, the complexity of your design depends on your constraints.

Hope that helps, let me know if you have any other questions.

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[Gábor Ziegler]

Thanks Curtis,

Do you know this card? https://www.elfa.se/en/nrf52840-mini-bluetooth-development-board-sparkfun-electronics-dev-15025/p/30152822?queryFromSuggest=true

It also claims ANT support and it looks as an Adafruit compatible dev-kit....

Thanks,

Gabor

[Gábor Ziegler]

Hmm,

Interesting findings:

• The manufacturer's page, where they explicitly claim arduino, C and CircuitPython support for nRF52840 Mini - Bluetooth Development Board : https://www.sparkfun.com/products/15025
• SparkFun Mini GPS Shield (also a datalogger with uSD card slot): https://www.sparkfun.com/products/14030
• ..and the corresponding GPS receiver: https://www.sparkfun.com/products/13670

What do you think about this combo? As a beginner in HW tinkering I would appreciate your insights

Thanks,

Gabor

[Curtis Malainey]

Personally my last few experiences with Sparkfun have left me disappointed, but maybe they have gotten things working. The docs claim the bootloader is based heavily off the adafruit one, so its possible that you may be able to flash the ANT softdevice. Just remember that my library is not setup (yet) to handled native ANT. That being said, the base code is there if you want to try and finish it. I will happily accept pull requests :) 

Make sure you read the "Software or Hardware Serial?" section of the nRF52 guide as it directly relates to your GPS radio and will likely save you a lot of headaches when debugging your connections.

This is likely your best chance outside of doing a similar setup with the adafruit feather system and crossing your fingers you can in fact flash the softdevices (hopefully its easier these days.)

I am planning to ramp up my contributions again in february and hopefully I can land this feature. Let me know if you have any other questions.

Curtis

[Gábor Ziegler]

Thanks Curtis!

Meanwhile I got response from SparkFun, it seems that Adafruit, or one of the DevKits from NordicSemi might be much easier solution. (Emphasis in the quote are from me):

"Hello from SparkFun Technical Support,

The GPS Mini Shield was designed to mate with the Arduino Pro Mini as the Hookup Guide covers (https://learn.sparkfun.com/tutorials/mini-gps-shield-hookup-guide). The GPS Mini Shield will not mate directly with the nRF52840 Development Board without modifying the board files to make it pin-compatible with the regular Pro Mini, unfortunately. Also, the Arduino libraries used for the GPS Mini Shield may not be compatible with the nRF52840. I would recommend reviewing the documentation for the libraries linked in the guide above to see if they will work.

Have a great day!"

I tend to be biased toward the Adafruit, though, due to the smaller form factor (better portability) and the built in LiPo battery support (compared to the meager C2032 batteries of the NordicSemi devkits).

Meanwhile I start to become greedy feature wise: after ANT+ sensor data I might want to add map-based navigation with a somewhat bigger screen, that might mean I will try to mate my existing RaspPi  and my no-name micro size ANT+ USB stick, then  I'll look for some RaspPi GPS shield and a color screen-shield

Thanks a lot for your advices,

Gabor

[P Gi]

Hi,

do you have the answer for this question " Do you have any concrete board + shield recommendation that can be used"?

I would like to start doind some  ANT+ fittness sensor

[Curtis Malainey]

Hi P,

Sorry it looks like our conversation completely fell off the mailing list. Gabor, Ryan and myself got ANT working adafruit nRF52 boards in the end. He posted about it in his blog here about how to get it working. That is probably among the lowest power solution, other than that, you can use an external Serial or SPI interfacing with the D52 module I list in my wiki on my ant-arduino lib and use a full featured serial/spi interface (e.g. CTS/RTS signaling) to get as much power savings as possible. Let me know if you have any other questions.

Curtis

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