RAK18032 WisBlock Audio Ultrasonic Microphone Module Datasheet

Overview

Description

RAK18032 is a WisBlock Audio that extends the WisBlock system based on the SPH0655LM4H-1 module from Knowles. This module is an ultrasonic 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: 40 uA ~ 690 uA
  • Chipset: SPH0655LM4H-1
  • Ultrasonic PDM Microphone
  • Left or right channel selection
  • Flat frequency response: 20 kHz - 80 kHz
  • Low distortion
  • High SNR
  • Bottom port
  • Omnidirectional sensitivity

• Module Size

  • 15 x 25 mm

Specifications

Overview

Figure 4075: RAK18032 WisBlock Audio Ultrasonic Microphone Module top and bottom view

Mounting

Mount to WisBlock Base

Figure 2 shows the mounting mechanism of the RAK18032 module on a WisBlock Base board. The RAK18032 module can be mounted on the IO slots.

Figure 4076: RAK18032 mounted to the WisBlock Base

Mount to WisBlock Audio Stack

With the use of WisBlock Audio Spacer, the RAK18032 can be mounted to any other WisBlock Audio module. Figure 3 shows the mounting mechanism of the RAK18032 on a WisBlock Audio Stack.

Figure 4077: RAK18032 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 RAK18032 Audio Ultrasonic Microphone Module.

Chipset

Vendor	Part number
SPH0655LM4H-1	Knowles

Pin Definition

WisBlock IO Connector

The RAK18032 WisBlock Audio Ultrasonic Microphone Module comprises a standard WisBlock connector. The WisBlock connector allows the RAK18032 module to be mounted to a WisBlock Base board. The pin order of the connector and the pinout definition is shown in Figure 4.

Figure 4078: RAK18032 WisBlock Module pinout diagram

NOTE

• 3V3 and GND are power supplies 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 RAK18032 WisBlock Audio PDM Microphone comprises a standard FPC connector. The FPC connector allows the RAK18032 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 5.

Figure 4079: RAK18032 FPC connector pinout diagram

NOTE

• 3V3 and GND are power supplies 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 RAK18032 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 (@ Fclock = 1.2 MHz)	-	650	690	uA
Isleep	Current consumption in Sleep Mode	-	40	45	uA
Sensitivity	94 dB SPL @ 1 kHz	-38	-37	-36	dBFS
SNR	Signal-to-noise ratio (94 dB SPL @ 1 kHz, A-weighted, Fclock = 1.2 MHz)	-	64.5	-	dB(A)
Clock	Input clock frequency	1.1	-	4.8	MHz
Top	Operating temperature range	-40	-	+100	°C

Figure 6 shows the RAK18032 typical free field ultrasonic response.

Figure 4080: RAK18032 typical free field ultrasonic response

Mechanical Characteristics

Board Dimensions

Figure 7 shows the dimensions and the mechanical drawing of the RAK18032 module.

Figure 4081: RAK18032 WisBlock Sensor mechanical drawing

WisBlock Connector PCB Layout

Figure 4082: WisBlock Connector PCB footprint and recommendations

Schematic Diagram

Digital Microphone

The Pin 2 of the SPH0655LM4H-1 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 RAK18032 is the right channel. But, you can remove the 10K Ohms 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 4083: RAK18032 WisBlock Ultrasonic Microphone schematic diagram

Figure 10 shows the full schematic diagram of the RAK18032 Audio PDM Microphone module.

Figure 4084: RAK18032 schematic diagram