Hardware setup
There are different possibilities to use the microSoundRecorder:
1.) with one or two I2S MEMS microphones (tested with the ICS43434) --> ACQ == _I2S_32 or ACQ == _I2S_32_MONO [BOTH TESTED !]
| Teensy 3.6 | -- | Mic1 | Mic2 | Mic3 | Mic4 |
|---|---|---|---|---|---|
| GND | GND | GND | GND | GND | |
| 3.3V | VCC | VCC | VCC | VCC | |
| Pin9 | BCLK | CLK | CLK | CLK | CLK |
| Pin23 | FS | WS | WS | WS | WS |
| Pin13 | RXD0 | SD | SD | -- | -- |
| Pin38 | RXD1 | -- | -- | SD | SD |
| GND | L/R | -- | L/R | -- | |
| 3.3V | -- | L/R | -- | L/R |
Example of two ICS43434 mics connected to the Teensy 3.6:
These are lousy prototype cable connections! For field use, it is highly recommended to:
- use as short connections as possible
- use shielded cables for the I2S connections
- use soldered connections
- use an RC lowpass filter (100µF electrolytic cap to GND, 1000 Ohm series resistor) to filter the 3.3V line from the Teensy before connecting it to the 3.3 Volts line of the ICS43434 PCB --> this reduces the noise by more than 10dB and increases your recording SNR to 65dB
The black bit in the lower left corner is a 3V lithium battery connected to GND = minus and Vbat = plus to power the built-in real time clock. The other two black bits are the two microphones (one of them has the header pins doubled in order to plug in the connections from the other mic)
The tiny little hole in the PCB is where the sound enters the mic
waterproof setup in zip plastic bag :-)
2.) with microphones connected to the Teensy audio board --> ACQ == _I2S [UNTESTED !]
tbd
3.) with microphones connected to TWO Teensy audio boards for quad channel audio --> ACQ == _I2S_QUAD [UNTESTED !]
tbd
4.) by connecting microphones to the ADC inputs [TESTED with ultrasonic mic]
_ADC_0 --> single ended ADC0
MEMS mic connected to microphone preamp and connected to ADC pin A2
NOT TESTED:
_ADC_D --> differential ADC0
_ADC_S --> stereo ADC0 and ADC1
Refer to the PJRC homepage for appropriate hardware biasing of the ADC inputs !