DIGILENT DIGIL 410-312 User guide

The Digilent Pmod MIC3 (Revision A) is small microphone module with a digital interface. With a Knowles Acoustics
SPA2410LR5H-B MEMs microphone and Texas Instrument's ADCS7476 12-bit Analog-to-Digital Converter, you can
capture your audio inputs with ease.

Pmod MIC3 Reference Manual

PDF

MEMSMicrophone module with digital interface
Transform audio inputs with 12-bitA/Dconverter
Adjust incoming volume with on-board potentiometer
Up to 1 MSPS of data
6-pin Pmod port with SPI interface
Follows Digilent Pmod Interface Specification Type 2

Download This Reference Manual

Features

The Pmod MIC3 is designed to digitally report to the host board whenever it detects any external noise. By sending a 12-bit
digital value representative of frequency and volume of the noise, this number can be processed by the system board and
have the received sound accurately reproduced through a speaker. The on-board potentiometer can be used to modify the
gain from the microphone into the ADC.

The Pmod MIC3 communicates with the host board via theSPI protocol. The 12 bits of digital data are sent to the system
board in 16 clock cycles with the most significant bit first. For the ADC7476, each bit is shifted out on each falling edge of
the serial clock line after the chip select line is brought low with the first four bits as leading zeroes and the remaining 12
bits representing the 12 bits of data. Thedatasheet for the ADC7476recommends that for faster microcontrollers or DSPs
that the serial clock line is first brought to a high state before being brought low after the fall of the chip select line to
ensure that the first bit is valid.

The Pmod MIC3 is capable of converting up to 1 MSa per second of 12-bit data, making it an ideal Pmod to use in
conjunction with thePmodI2Sfor an audio development application.

Any external power applied to the Pmod MIC3 must be within 3V and 5.5V to ensure that the on-board chips operate
correctly; however, it is recommended that Pmod is operated at 3.3V.

A sample timing diagram taken from the ADCS7476 datasheet representing the data that will be received by the system
board from the Pmod is provided below:

Pin Signal Description

1 SS Chip Select

2 NC Not Connected

3 MISO Master-In-Slave-Out

4 SCK Serial Clock

5 GND Power Supply Ground

6 VCC Power Supply (3.3V/5V)

Functional Description

Interfacing with the Pmod

Pinout Table Diagram

Timing Diagram

The pins on the pin header are spaced 100 mil apart. The PCB is 1.1 inches long on the sides parallel to the pins on the pin
header and 0.8 inches long on the sides perpendicular to the pin header.

The schematics of the Pmod MIC3 are availablehere. Additional information about theADCincluding communication
modes and specific timings of the chip can be found by checking out its datasheethere. The datasheet for the microphone
can be foundhere.

Example code demonstrating how to get information from the Pmod MIC3 can be foundhere.

If you have any questions or comments about the Pmod MIC3, feel free to post them under the appropriate section (“Add­on Boards”) of theDigilent Forum.

Physical Dimensions

Additional Information