AudioMoth: Difference between revisions

From RevSpace
Jump to navigation Jump to search
 
(11 intermediate revisions by the same user not shown)
Line 13: Line 13:
Ideas:
Ideas:
* general clean-up
* general clean-up
** fix white space, remove many of the empty lines (earlier CR/LF mistake?)
** fix white space, remove many of the empty lines (earlier CR/LF mistake?), like these https://github.com/bertrik/AudioMoth-Firmware-Basic/blob/master/main.c#L154
** fix sprintf statements
** fix sprintf statements, like these https://github.com/bertrik/AudioMoth-Firmware-Basic/blob/master/main.c#L167
** fix complicated and non-portable casts (sensitive to endianness)
** fix complicated and non-portable casts (sensitive to endianness), like this https://github.com/bertrik/AudioMoth-Firmware-Basic/blob/master/main.c#L161
* update tool-chain to newer version
* update tool-chain to newer version
** update gcc
** update gcc
Line 26: Line 26:


== Hardware ==
== Hardware ==
[[File:SPM0408LE5H_response.png|thumb|right|Frequency response]]
See https://circuithub.com/projects/OpenAcoustics/AudioMoth
See https://circuithub.com/projects/OpenAcoustics/AudioMoth


The microphone is SPM0408LE5H, [https://www.mouser.com/datasheet/2/218/-532499.pdf datasheet].
The microphone is a [https://www.mouser.com/datasheet/2/218/-532499.pdf SPM0408LE5H].
Can't find much about it's ultrasonic performance. The official graph shows a hint of resonance above 10k so it does have sensitivity.
Can't find much about its ultrasonic performance. The official graph shows a hint of resonance above 10k so it does have ultrasonic sensitivity.
For frequencies higher than the resonance peak the response of a typical microphone drops of with 6 dB/octave.
For frequencies higher than the resonance peak the response of a typical microphone drops off steeply with 6 dB/octave.
I have been able to record some pipistrelle bats with it (40 - 50 kHz).
I have been able to record some pipistrelle bats with it (40 - 50 kHz).


The processor is EFM32WG380F256, [https://www.silabs.com/mcu/32-bit/efm32-wonder-gecko/device.efm32wg380f256-qfp100 link]
The processor is EFM32WG380F256, [https://www.silabs.com/mcu/32-bit/efm32-wonder-gecko/device.efm32wg380f256-qfp100 link]
Where is the schematic?


== Software ==
== Software ==
My fork on github: https://github.com/bertrik/AudioMoth-Project
My fork on github: https://github.com/bertrik/AudioMoth-Project
=== Suggested trigger extension ===
A bat specific trigger is desireable because this way we only get "interesting" files.
The idea is that bat signals are, in general:
* ultrasonic, frequency above 10 kHz
* organised in short pulses, e.g. 8 pulses per second of 5 ms each for a pipistrelle
Challenges:
* crickets, sound is also at least partly ultrasonic, overlapping with the calls of some of the larger bats and with social bat calls in general
Proposed algorithm:
# Apply a high-pass filter at about 10 kHz, this needs not be super-sharp filter. Perhaps just a simple 1-pole IIR (easy to calculate).
# Calculate the energy in each millisecond by summing the squared amplitude of the high-pass filtered signal over this millisecond. Perhaps we can also just calculate variance here and forget about step 1).
# Calculate a running average energy over several (say 500) of these milliseconds values.
# If the millisecond energy exceeds the average energy by a factor X (the sensitivity of the trigger) for a duration of Y consecutive milliseconds, consider the trigger to be active.


=== Running the tools ===
=== Running the tools ===
Running the tools (configuration tool, flash tool, etc) requires the --no-sandbox option (at least on my system), for example
Running the AudioMoth tools (configuration tool, flash tool, etc) requires the --no-sandbox option (at least on my system), for example
   ./AudioMothConfigurationAppSetup1.2.5.AppImage --no-sandbox
   ./AudioMothConfigurationAppSetup1.2.5.AppImage --no-sandbox


=== IDE for development ===
=== IDE for development ===
A brave attempt for all the steps to get the firmware compiled was written here:
A description of all steps to get the firmware compiled is written here:
https://github.com/OpenAcousticDevices/AudioMoth-Project/wiki/AudioMoth
https://github.com/OpenAcousticDevices/AudioMoth-Project/wiki/AudioMoth



Latest revision as of 09:43, 7 April 2021

Project AudioMoth
Audiomoth.png
Status In progress
Contact bertrik
Last Update 2021-04-07

What

I have an AudioMoth board, and plan to improve its software:

Ideas:

Hardware

Frequency response

See https://circuithub.com/projects/OpenAcoustics/AudioMoth

The microphone is a SPM0408LE5H. Can't find much about its ultrasonic performance. The official graph shows a hint of resonance above 10k so it does have ultrasonic sensitivity. For frequencies higher than the resonance peak the response of a typical microphone drops off steeply with 6 dB/octave. I have been able to record some pipistrelle bats with it (40 - 50 kHz).

The processor is EFM32WG380F256, link

Where is the schematic?

Software

My fork on github: https://github.com/bertrik/AudioMoth-Project

Suggested trigger extension

A bat specific trigger is desireable because this way we only get "interesting" files.

The idea is that bat signals are, in general:

  • ultrasonic, frequency above 10 kHz
  • organised in short pulses, e.g. 8 pulses per second of 5 ms each for a pipistrelle

Challenges:

  • crickets, sound is also at least partly ultrasonic, overlapping with the calls of some of the larger bats and with social bat calls in general

Proposed algorithm:

  1. Apply a high-pass filter at about 10 kHz, this needs not be super-sharp filter. Perhaps just a simple 1-pole IIR (easy to calculate).
  2. Calculate the energy in each millisecond by summing the squared amplitude of the high-pass filtered signal over this millisecond. Perhaps we can also just calculate variance here and forget about step 1).
  3. Calculate a running average energy over several (say 500) of these milliseconds values.
  4. If the millisecond energy exceeds the average energy by a factor X (the sensitivity of the trigger) for a duration of Y consecutive milliseconds, consider the trigger to be active.

Running the tools

Running the AudioMoth tools (configuration tool, flash tool, etc) requires the --no-sandbox option (at least on my system), for example

 ./AudioMothConfigurationAppSetup1.2.5.AppImage --no-sandbox

IDE for development

A description of all steps to get the firmware compiled is written here: https://github.com/OpenAcousticDevices/AudioMoth-Project/wiki/AudioMoth

Compiling

platformio

It compiles and produces a firmware.bin file, but it's not recognized by the flashing tool as a valid file.

Use this platformio.ini file:

 [platformio]
 src_dir = src,fatfs_src
 include_dir = inc,fatfs_inc
 [env:default]
 framework = zephyr
 platform = siliconlabsefm32
 board = efm32wg_stk3800

Install platformio:

 sudo apt install python3-pip
 sudo pip3 install platformio
 sudo pip3 install -U PyYAML

Compile it:

 pio run