RAK18031 WisBlock Audio PDM Microphone Module Datasheet

Overview

Description

RAK18031 is a WisBlock Audio that extends the WisBlock system based on the MP34DT06JTR module from ST. This module is a mono PDM microphone module, where the analog audio is converted to a Pulse Density Modulation (PDM) output. When used with other WisBlock modules, you can achieve rich applications such as audio monitoring, recording, and even voice control functions.

Features

• Sensor Specifications

  • Voltage supply: 3.3 V ~ 3.6 V
  • Current consumption: 5 uA ~ 650 uA
  • Chipset: MP34DT06JTR
  • PDM Microphone
  • Left or Right Channel Selection
  • Flat frequency response: 100 Hz - 10,000 Hz
  • Low distortion of 6% at 120 dB SPL
  • 64 dB(A) Signal-to-Noise Ratio
  • Omnidirectional sensitivity

• Module Size

  • 15 x 25 mm

Specifications

Overview

Figure 1: RAK18031 WisBlock Audio PDM Microphone Module top and bottom view

Mounting

Mount to WisBlock Base

Figure 2 shows the mounting mechanism of the RAK18031 module on a WisBlock Base board. The RAK18031 module can be mounted on the IO slots.

Figure 1: RAK18031 mount to WisBlock Base

Mount to Enclosure

If you want to use the RAK18031 with an enclosure, there are two (2) mounting screw holes that are provided to mount the microphone module up against a hole in the enclosure. In this case, an FPC or a WisBlock IO Extension Cable is required to connect the RAK18031 to the WisBlock system.

NOTE

• The FPC with the Audio Interposer board is recommended as it provides a better mechanical mounting than the IO extension cable.

Figure 1: RAK18031 mounted to the enclosure

Mount to WisBlock Audio Stack

With the use of WisBlock Audio Spacer, the RAK18031 can be mounted to any other WisBlock Audio module. Figure 4 shows the mounting mechanism of the RAK18031 on a WisBlock Audio Stack.

Figure 1: RAK18031 mounted to the WisBlock Audio Stack

Hardware

The hardware specification is categorized into five (5) parts. It shows the chipset of the module and discusses the pinouts and their corresponding functions and diagrams. It also covers the electrical and mechanical parameters that include the tabular data of the functionalities and standard values of the RAK18031.

Chipset

Vendor	Part number
MP34DT06JTR	ST

Pin Definition

WisBlock IO Connector

The RAK18031 WisBlock Audio PDM Microphone comprises a standard WisBlock connector. The WisBlock connector allows the RAK18031 module to be mounted to a WisBlock Base board. The pin order of the connector and the pinout definition is shown in Figure 5.

Figure 1: RAK18031 WisBlock Module pinout diagram

NOTE

• 3V3 and GND are power supply from the WisBlock Base.
• MIC_CTR_IO1 is the GPIO from WisBlock Core. The MIC can be controlled as a left or right channel.
• MIC_PDM1_Data and MIC_PDM1_CLK are PDM signals.

WisBlock FPC Connector

The RAK18031 WisBlock Audio PDM Microphone comprises a standard FPC connector. The FPC connector allows the RAK18031 module to be connected to a WisBlock Audio Interposer board, such as RAK18003. The pin order of the connector and the pinout definition is shown in Figure 6.

Figure 1: RAK18031 FPC connector pinout diagram

NOTE

• 3V3 and GND are power supply from the WisBlock Audio Interposer board.
• MIC_CTR_IO1 is the GPIO from the Interposer board. The MIC can be controlled as a left or right channel.
• MIC_PDM1_Data and MIC_PDM1_CLK are PDM signals.
• MIC_Check is a signal to let the Interposer board know if the RAK18031 exists or is connected.

Electrical Characteristics

Acoustic and Electrical Specifications

Symbol	Description	Min.	Nom.	Max.	Unit
VDD	Supply voltage	1.6	3.3	3.6	V
Idd	Current consumption in normal mode (VDD = 1.8 V, Clock = 2.4 MHz)	-	650	-	uA
Isleep	Current consumption in Sleep Mode	-	-	5	uA
Sensitivity	94 dB SPL @ 1 kHz	-27	-26	-25	dBFS
SNR	Signal-to-noise ratio (94 dB SPL @ 1 kHz, A-weighted)	-	64	-	dB(A)
Clock	Input clock frequency	1.2	2.4	3.25	MHz
Top	Operating temperature range	-40	-	+85	°C

Mechanical Characteristics

Board Dimensions

Figure 7 shows the dimensions and the mechanical drawing of the RAK18031 module.

Figure 1: RAK18031 WisBlock Sensor mechanical drawing

WisBlock Connector PCB Layout

Figure 1: WisBlock Connector PCB footprint and recommendations

Schematic Diagram

Digital Microphone

The Pin 2 of the MP34DT06JTR is used to control the MIC as a left or right channel.

• The MIC is the left channel when Pin 2 is HIGH.
• The MIC is the right channel when Pin 2 is LOW.

By default, the RAK18031 is the right channel. But, you can remove the 10 kΩ resistor on R9 and connect it to R8 to change the MIC to the left channel as its default. You may also use MIC_CTR_IO1 to select the MIC as the right or left channel.

Figure 1: RAK18031 Digital Microphone schematic diagram

Figure 10 below shows the full schematic diagram of the RAK18031 Audio PDM Microphone module.

Figure 1: RAK18031 schematic diagram