microPAM concept

Requirements

• commercial off the shelf (COTS) components

• low cost

• easy programmable

• easy to setup

Using COTS components minimizes the need for hardware development. The resulting system may be somewhat more expensive than a monolitic system, but offers the advantage that COTS compents are typically produced in quantity with an acceptable cost margin.

The microPAM consists of four major components

• microphone

• control processor (MCU)

• data storage

• power supply

microPAM-T4

Using a Teensy4.1 as MCU, the data storage in form of a microSD card is already integrated.

microPAM-pico

using a RP2040 as MCU, the data storage must be added using a seperate microSD card

Constraints

There are two major constraints on any PAM system:

• data quantity

• power supply

The concept of the microPAM is based on microSD cards, the capacity of which may mowadays reach 1000 GByte, or equivalently >130 days continuous 16-bit CD quality (44.1 kHz) recording. Loss-less compression may increase this by a factor 2 or 3, depending on the background noise level.

The power supply is still a major issue as batteries are typically heavy and bulky. For the microPAM, the concept is to seperate the power supply from the microPAM proper (microphone + storage + micro controller) as much as possible. This way the microPam proper can then be made very compact.

The hardware implementation, therefore, should be as flexible as possible.

Software setup

The easiest way to setup a software environment is to follow

• the Arduino instructions https://docs.arduino.cc/software/ide-v2/tutorials/getting-started/ide-v2-downloading-and-installing for setting up Arduino 2.x

• the Teensy instructions https://www.pjrc.com/teensy/td_download.html for setting up the Teensy environment

• the RP2040 instructions earlephilhower/arduino-pico for setting up the RP2040 environment

While these instructions are agnostic of each other they can easily co-exist by copying both package indices

• earlephilhower/arduino-pico

• https://www.pjrc.com/teensy/package_teensy_index.json

into seperate lines in the “Additional Boards Manager URLs” field of the “File->Preferences->Settings” tab

Obviously, if only Teensy is used, the RP2040 software must not be installed, and vice versa.

Once Arduino is installed, it is useful to check “Show files inside sketches” in the “File->Preference->Settings” tab. This allows to open/edit fils that in the subdirectories of the sketch.