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Feather accelerometer, RF transmitter, data logging project.
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Re: Feather accelerometer, RF transmitter, data logging proj

by wahleworld on Thu Nov 29, 2018 3:31 pm

What type of power consumption in general can be expected from the feather MO? I need sub 5 mA consumption average, but can alot for more consumption during detect/write/transmit, with the potential of 2500 mAh system capacity via 3 AA batteries in series.

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Re: Feather accelerometer, RF transmitter, data logging proj

by adafruit_support_bill on Thu Nov 29, 2018 3:44 pm

For the Feather M0 itself, sub-5mA should be possible in sleep mode - and much lower in deep-sleep mode.

For most efficient operation of the Feather, a 3.7v LiPo is recommended. There is a built-in LiPo charger circuit for automatic recharge when plugged in via USB.

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Re: Feather accelerometer, RF transmitter, data logging proj

by wahleworld on Thu Nov 29, 2018 4:06 pm

Bill, thank you again for all of the input.

I don't have the greatest understanding of the sleep-modes and device functionality. I'm wondering, if the device were in sleep-mode, would the accelerometer attached via protowing be able to detect motion, and quickly wake the board, and write the data to storage, and transmit an RF signal in a short period of time?

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Re: Feather accelerometer, RF transmitter, data logging proj

by adafruit_support_bill on Thu Nov 29, 2018 5:50 pm

I'm not familiar with all the details of the M0 power management. But typically power management capabilities will include the ability to be awakened via an interrupt or other external signal. And some of the accelerometers can be configured to generate an interrupt based on free-fall or some acceleration threshold.

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Re: Feather accelerometer, RF transmitter, data logging proj

by wahleworld on Fri Nov 30, 2018 3:20 am

Here are my thoughts on a possible "wake-up" scenario for the M0. I will figure out how to code the process, but I'm wondering if the general process seems feasible using the following equipment.

Hardware
A. Feather MO RFM69HCW
B. Protowing mounted to feather, with accelerometer attached

PROCESS: UPON IMPACT OF SENSOR UNIT
1. acceleration detection above specified threshold would act as interrupt and awaken MCU, optimally within sub-0.1s timeframe.
2. Immediately following interrupt signal/mcu "wake up", Raw accelerometer data would be stored, and RF signal would be transmitted.

Does this seem feasible, if a given impact lasts less than a second

I'm not familiar with the size of an average code file. Would I be able to store the device code, and several packets of data with the 256k Flash?

Thanks in advance.

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Re: Feather accelerometer, RF transmitter, data logging proj

by adafruit_support_bill on Fri Nov 30, 2018 7:13 am

That sounds feasible.

Would I be able to store the device code, and several packets of data with the 256k Flash?

You can store a lot of code in the Flash. But your collected data would go in RAM. The M0 has 32K of that.
https://learn.adafruit.com/memories-of- ... o-memories

Some RAM will be needed for stack, heap and radio communication buffers. But based on my calculations above, .5 seconds of 1KHz data would need just 3K.

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Re: Feather accelerometer, RF transmitter, data logging proj

by wahleworld on Fri Dec 07, 2018 11:36 pm

Are the feather boards durable to a reasonable extent?

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Re: Feather accelerometer, RF transmitter, data logging proj

by adafruit_support_bill on Sat Dec 08, 2018 8:07 am

They are not "mil-spec", but they are built to pretty high standards for a 'commercial-grade' circuit using a thicker than average fiberglass board.

If it will be subjected to repeated high physical stress, you might consider conformal coating or potting for added protection.

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Re: Feather accelerometer, RF transmitter, data logging proj

by wahleworld on Sun Dec 16, 2018 6:16 pm

Do you happen to know what voltage regulator is used on the Feather Boards? Or perhaps how much quiescent current on average is consumed by it?

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Re: Feather accelerometer, RF transmitter, data logging proj

by adafruit_support_bill on Mon Dec 17, 2018 6:46 am

The schematics are linked in the guide: https://learn.adafruit.com/adafruit-fea ... /downloads
The datasheet for the regulator is here: https://www.diodes.com/assets/Datasheets/AP2112.pdf

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Re: Feather accelerometer, RF transmitter, data logging proj

by wahleworld on Fri Dec 21, 2018 3:09 pm

Thanks!

I've started soldering a few of the components together, and am currently looking at the LIS3DH accelerometer. I'm wondering what the pins labeled A1, A2, A3 are for? I don't see any information on the pinout page.

Thanks

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Re: Feather accelerometer, RF transmitter, data logging proj

by adafruit_support_bill on Fri Dec 21, 2018 3:52 pm

Those are connected to the auxiliary ADC inputs. There is only passing mention in the data sheet:
https://cdn-shop.adafruit.com/datasheets/LIS3DH.pdf

But a little more detail in section 10 of the app note:
https://cdn-shop.adafruit.com/datasheet ... =100,0,116

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Re: Feather accelerometer, RF transmitter, data logging proj

by wahleworld on Fri Dec 21, 2018 5:03 pm

Thank you.

Just to clarify, those pins are for various analog sensor attachment, with the purpose of converting their analog signal to digital?

In my case, I will not be using any analog sensor, and therefore won't be using the A1, A2, A3 pins, correct?

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Re: Feather accelerometer, RF transmitter, data logging proj

by adafruit_support_bill on Fri Dec 21, 2018 5:29 pm

That is correct. They are not well documented by the manufacturer and I don't know of anyone that is actually using them. But we had space on the board, so we decided to add breakout holes for them.

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Re: Feather accelerometer, RF transmitter, data logging proj

by wahleworld on Fri Dec 21, 2018 5:31 pm

Seems appropriate to have them just in case.. Thanks again, Bill.

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