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Motion measruament
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Please be positive and constructive with your questions and comments.

Motion measruament

by flaviaelia on Wed Jun 21, 2017 7:49 am

Hey there! Im making a project to measure acceleration from a soccer player!

I got a wearable FLORA V3 board, combined with a Flora accelerometer/gyroscope/magnetometer.
It works properly with the USB, however I have some other doubts:

1 - Since it is wearable, I would like to use a very discreet coin cell battery. But it should last for the whole match (90 minutes at least). Do you recommend me any specific?
2 -The end prototype should be wireless. Is it possible to do this with the FLORA board or only with the GEMA bluetooth? Could you advise me better on that?

If you have any other comments, please let me know so I can improve my project!

Thank you!
Flávia.

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Re: Motion measruament

by adafruit_support_bill on Wed Jun 21, 2017 7:56 am

1 - Coin cells do not have much capacity and do not do well at all with higher current loads such as writing to an SD card or transmitting via wireless. I'd recommend one of the smaller LiPo cells instead. https://www.adafruit.com/category/574
2 - For wireless, I'd recommend one of the Feather processors with a built-in wireless module: https://www.adafruit.com/category/835

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Re: Motion measruament

by flaviaelia on Thu Jun 22, 2017 7:43 am

Thank you for your reply!
1 - We made a calculation that the sensor and the Flora would need 30mAh together and the usage would be for 2 hours. We came to a value of a battery of 6V. Do you still think the coin cells wouldnt be enough?

2 - Since our project is a wearable for an athlete, the board would be too much to add in the textile. Do you think the GEMA is still too weak for the project?

3 - One more thing, we are using the conductive yarn 3ply for embroidery. Is the resistance ok for this project?

Thanks!

flaviaelia
 
Posts: 2
Joined: Wed Jun 21, 2017 7:45 am

Re: Motion measruament

by adafruit_support_bill on Thu Jun 22, 2017 8:01 am

We made a calculation that the sensor and the Flora would need 30mAh together and the usage would be for 2 hours. We came to a value of a battery of 6V.

Volts and milliamps are two completely different things. More volts won't give you a longer run-time. it will just make your processor's voltage regulator get hotter.

The Flora is a 3.3v processor, so anything more than that is just wasted as heat by the voltage regulator. A 3.7v LiPo cell is pretty close to perfect for powering 3.3v devices like the Flora.

Capacity is measured in milli-amp-hours (mAh). If you need 30mA for 2 hours, you need a battery with at least 30ma * 2h = 60mAh capacity. This one is 100mAh, so it should do the job. https://www.adafruit.com/product/1570

But if you want to transmit wirelessly, you need to calculate the current requirements for that too. For example, the ATWINV1500 WiFi module requires 172mA to transmit. You probably won't be transmitting 100% of the time. You will need to define how much data you will be sending and how frequently you will be sending it. From that you can estimate the battery capacity required for wireless operation.
https://www.adafruit.com/product/2999

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