Audio hub demonstration kit supporting the M45DT02, MP34DB01

AN4227
Application note
Audio hub demonstration kit supporting the MP45DT02,
MP34DB01, and MP34DT01 microphones
Introduction
This document provides a brief description of the audio hub demonstration board STEVALMKI138V1 available from www.st.com along with simple steps to use the board with the
APWorkbench software tool.
The purpose of this board is twofold:
1.
It can be used as an STSmartVoice interface. In combination with this board
(STEVAL-MKI126Vx), it manages the signal coming from the onboard microphones.
The STSmartVoice board hosts up to six microphones and the STA321MPL
microphone processor converts the PDM signals from them into the common I2S audio
format. (For additional details, please refer to AN4146 “STSmartVoice demonstration
board STEVAL-MKI126Vx” available from www.st.com). Basically the audio hub, using
the STM32F107RC microcontroller, is able to program the STA321MPL device via the
I2C and decodes the I2S into a USB stream in order for the PC to manage the sound
captured by the microphones. Multiple features for using the microphones on the
STSmartVoice demonstration board are listed and accessible thanks to the
APWorkbench software tool.
2.
It can be used as a USB sound card. As shown in Figure 1, the audio hub board hosts
either the MP45DT02 or MP34DT01 (top-port digital microphones) and the MP34DB01
which is a bottom-port digital microphone. The board is able to host both types of
microphones as shown below. The task of the STM32 microcontroller is to decode the
PDM signals coming from the microphones and stream the audio via the USB.
Figure 1. STEVAL-MKI138V1
Entire board (top and bottom views)
MP45DT02
MP34DB01
MP34DT01
Microphone section (zoom)
March 2013
DocID024106 Rev 1
1/13
www.st.com
Contents
AN4227
Contents
1
Hardware description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2
Software description (getting started with APWorkbench) . . . . . . . . . . 6
2.1
STSmartVoice interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.2
USB voice recorder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Appendix A Schematics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Appendix B Layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3
2/13
Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
DocID024106 Rev 1
AN4227
Hardware description
The connection is done through a USB cable that supplies the board and also streams the
audio collected by the microphones to the PC.
Figure 2. Block diagram - microphone USB demonstration board
ST Audio HUB
MCLK
Mic_Vdd
SEL
MIC_DATA12
Vdd
Vdd
Out
Clk
L/R
J1
LRCK
BICK
SDO12
SDO34
SDO56
Mic_Vdd
MIC_CK
12.288 MHz
SDA
SCL
1
Hardware description
Out
gnd
I2C
I2S
µC_Vdd
L/R
gnd
STM32F107RC
SEL
Mic_Vdd
SPI
SPI_CK
MIC_CK
Clk
SEL
MCO
J5
Mic_Vdd
Timer
USB I/F
3.3V
12.288 MHz
OSC
µC_Vdd
Mic_Vdd
Regulator
3.3V
5V
USB
Connector
D1
D2
D3
D4
D5
Referring to Figure 2:
•
The supply section of the board is made up of one voltage regulator that steps down
the 5 V of the USB connection to 3.3 V. The supply voltage ranges of the digital
microphones are given below in Table 1.
Table 1. Supply voltage range of microphones
•
Part number
Min.
Typ.
Max.
MP45DT02
1.64
1.8
3.6
MP34DB01
1.64
1.8
3.6
MP34DT01
1.64
1.8
3.6
Regarding the microphone sections, the MEMS outputs are a PDM signal, which is a
high-frequency (1 to 3.25 MHz) stream of 1-bit digital samples. The “Functionality”
section of each microphone datasheet (available on www.st.com) provides details
concerning the connections of the microphone in single channel configuration or stereo
configuration by setting the LR pin. This pin sets the validity of the output data on the
high level of the clock or on the low level as shown in Table 2.
Table 2. L/R channel selection
L/R
Clock low
Clock high
GND
Data valid
High impedance
VDD
High impedance
Data valid
DocID024106 Rev 1
3/13
Hardware description
AN4227
In this board the microphones are used in stereo configuration, so the two digital outputs are
shorted (Mic_DATA12, refer to schematic) and the two MEMS LR pins must be respectively
set one to GND and the other one to VDD. On the board, the resistors R1 and R13 already
set the LR pin of the microphones, R1 and R42 give the user the possibility to change the
MEMS polarity. Note that the PCB sections hosting the MEMS microphones are detachable.
This option has been considered to let the user put the microphones in the desired position
(i.e. for a display application in which the microphones are placed at the edges of the
display).
•
The hardware relative to the STM32F107RC microcontroller has been chosen to
support both modes of usage listed above (either STSmartvoice interface or USB
sound card).
The board hosts two clock devices, the first one is a crystal quartz at 12.288 MHz and
the other one is an active oscillator at 12.288 MHz as well. The first one, connected to
the OSC_IN and OSC_OUT pins, serves to generate the entire internal clock of the
microcontroller (STM32 clock tree). Once the clock tree has been set, all the internal
peripherals of the microcontroller have their own clocks.
If the ST audio hub is used as the STSmartVoice interface, the internal clock tree
provides the clock for the USB, for the I2C cell, for the I2S cell and also provides the
clock for the daughterboard through the MCO pin (12.288 MHz as well). The
microcontroller is used to program the STA321MPL via I2C and also is used to decode
the I2S coming from the daughterboard and to stream the audio via the USB. For this
reason dedicated STM32 pins are connected to the connector physically interfacing the
STSmartVoice board. An additional clock device (active oscillator) has been mounted
for debugging purposes only. In the default configuration, the selector composed of
R42, R21, and R17 is set to connect the MCLK trace to the MCO pin (refer to the
schematic).
If the ST Audio hub is used as a USB sound card, the clock tree is used to provide the
MIC_CK and SPI_CK thanks to internal timers and a dedicated loop trace on the board
(short between pin 21 and pin 27). The STM32 samples the output data of the
microphones using the synchronous serial port (SPI1). The microphone signal
MIC_DATA12 is a stereophonic signal and the SPI must be able to sample both
channels. Since MIC_DATA12 is synchronous with its clock, SPI_CK must be doubled.
Summarizing, the timer generates:
–
MIC_CK = 3.072 MHz
–
SPI_CK = 6.144 MHz
The supported microcontroller USB interface allows streaming the audio on the USB
peripheral, rendering this demonstration board compatible with any laptop or desktop.
4/13
DocID024106 Rev 1
AN4227
Hardware description
•
Some LEDs have been mounted on the board, thus allowing a real-time check of what
the demonstration board is performing. LEDs D1 and D5 give feedback about the
supply and successful enumeration while the purpose of D2, D3 and D4 is to check the
status of the board. D2 and D3 will alternately blink while the STM32 is in DFU mode
(before the dedicated firmware has been correctly loaded into the flash memory of the
microcontroller). Checking the PC “Device Manager”, the STM device in DFU mode will
appear (see Figure 3 below).
Figure 3. Device manager when STM32 is in DFU mode
The audio hub boards are provided by ST with the firmware already loaded; the DFU
section has been included to allow a firmware update by the user with no need for flash
loader kits and is directly supported by the APWorkbench tool. The status of LEDs D1-D5 is
summarized in the table below.
Table 3. LED status
D1
ON: USB
enumeration
successful
D2
D3
Blinking: DFU mode
Blinking: DFU mode
Off: Firmware correctly Off: Firmware correctly
downloaded
downloaded
DocID024106 Rev 1
D4
D5
Off: Firmware correctly
ON: Board supplied
downloaded
5/13
Software description (getting started with APWorkbench)
2
AN4227
Software description (getting started with
APWorkbench)
The firmware of the ST audio hub supports two different audio frameworks. In the first case
the board can be used as the interface for the STSmartVoice, allowing the I2C programming
and the decoding of the I2S coming from the daughterboard. When the board is used for this
purpose, it will be recognized as "STAudioHub interface"(a). The other possibility is the use
of the board essentially as a PDM decoder that allows the couple of microphones on the
board to be interfaced directly to the PC via the USB in which case the board will be
recognized by the operative system as "STM32 Capture PDM mode".
The APWorkbench tool allows choosing one of these modes by following these simple
steps:
2.1
1.
Run the tool
2.
Click on the "MEMS Microphones Demo Kit" button
3.
Select the mode in the "Microphone Kit selection" box
4.
Click on the "Run Selected Application…" button
STSmartVoice interface
If the user wants to operate the board as the STSmartVoice interface, the corresponding
mode must be selected as shown in Figure 4.
Figure 4. APWorkbench launch wizard (STSmartVoice demonstration kit)
a. APWorkbench is compatible with Windows XP, Windows Vista and Windows 7.
6/13
DocID024106 Rev 1
AN4227
Software description (getting started with APWorkbench)
After this selection, the setup wizard panel of the STSmartVoice supported configurations
will appear. For a detailed description of the meaning of the configurations listed in Figure 5,
please refer to AN4146 "STSmartVoice demonstration board STEVAL-MKI126Vx" available
on www.st.com.
Figure 5. STSmartVoice - setup wizard
DocID024106 Rev 1
7/13
Software description (getting started with APWorkbench)
2.2
AN4227
USB voice recorder
If the user wants to operate the board as a USB voice recorder, the proper mode must be
selected as depicted in Figure 6.
Figure 6. APWorkbench launch wizard (USB digital voice recorder)
Once this selection has been run, a dedicated panel will appear. If the user wants to operate
the board as a USB voice recorder, the tool shows the panel performing either FFT or scope
monitoring. It is also possible to record the signal sensed by the microphones on the board.
Figure 7. USB voice recorder - FFT monitoring
8/13
DocID024106 Rev 1
Schematics
AN4227
Appendix A
Figure 8. Board schematic (power supply and JTAG connector)
<Power Supply>
UC_VDD
VCC_USB
UC_VDD
1
R23
10k
1K
1
D1
LED-1
180
2
E
R38
1k
2
C41
10nF
C40
1
VCC_USB
D5
LED-1
2
DocID024106 Rev 1
J7
VBUS 1
D- 2
D+ 3
ID 4
GND 5
Mini TypeB
U8
1 I/O1
I/O1 6
2 GND
VBUS 5
3 I/O2
I/O2 4
USBLC6-2
2
2
R6 22
R12 22
1
3
1
2
2
UC_VDD
A_VDD
BEAD
1
C39
100nF
L6
BEAD
L1
U4
L4
2
MIC_VDD
BEAD
LD1117
+
C3
10uF
C49
100nF
1
1
R8
1.5K
33uF
+
2
BEAD
R26
4
E
R22
36k
GND
Q2
B
1
2
Vout
2
2
2
R24
1
Vin
1
C
1
3.3V
L3
INDUCTOR2
R27
0R0 NC
Q1
B
2
USB_DISC
VCC_USB
1
C
2
Vout
R25
47k
2
1
1
USBDM
1
USBDP
C5
100nF
<JTAG>
UC_VDD
1
1
R2
10K
1
R3
10K
2
R4
10K
2
UC_VDD
2
JTMS
JTCK
STM32_I2S_BICK
STM32_I2S_LRCK
NRST
2
3
6
5
8
7
1
R15
10K
2
9
J2
9/13
Schematics
JRST
4
10
1
JP3
JP
5X2_HEADER
2
1
<Mangusta option>
R39
0R0 NC
C29
2.2uF
STM32_I2S_BICK
2
L/R
MIC1LR
MIC1LR
2
4
MIC_DATA12
DATA
VDD
1
GND
2
LR
3
GND
VDD
6
DOUT
5
CLK
4
0R
MIC_DATA12
R42
MIC1CK
1
MIC_VDD
MP45DT01
MP34DT01
2
1
R28
100
C26
15pF
MIC_CK
C25
15pF
R18
0R
2
3
4
I2S_BICK
5
6
7
8
9
10
44
43
11
12
USBDM
13
14
MCLK
15
2
MCO
TP2
39
TP3
38
STM32_I2S_MCLK
37
STM32_I2S_MCLK
36
STM32_I2S_DATA12
1
R1
0R NS
SDA
FAIL
MIC2LR
C6
NS
C7
10pF
5
CLK
4
2
C20
15pF
R29
C19 100
15pF
MIC_DATA12
MIC2CK
1
MIC_CK
U11
MIC2CK
U9
VDD
4
DATA
5
4
3
3
L/R
2
CLK
1
MP34DB01
3
4
CLK
DATA
L/R
VDD
2
1
MIC2LR
MIC_VDD
MP34DT01
4
MIC_DATA12
1
3
2
1
MIC_CK
MIC_DATA12
J6
CON4
12.288_CK
MIC_DATA12
MIC_CK
3
1
J10
CON4
2
MIC_VDD
1
J8
CON4
R14
0R0
UC_VDD
DOUT
C8
10pF
J15
2
2
6
MCO
4
MIC_VDD
STM32_LQFP64
GND
STM32_I2S_MCLK
3
STM32_I2S_LRCK
LR
3
VDD
MP45DT01
12.288_CK
2
33
2
16
MIC_VDD
STM32_I2S_BICK
GND
STBY
35
34
R41
0R
RESET
1
2
42
40
R19 100
2
1
USBDP
USB_DISC
41
1
R20100
C21
100nF
U1
I2S_LRCK
GND
45
2
SCL
MUTE
VSS_CAP
C22
10uF
MIC_VDD
I2S_DAT_34
5
JTMS
0R
46
2
50
51
1
GND
47
LED3
UC_VDD
I2S_DAT_12
I2S_DAT_56
2
C16
4.7uF
4
VDD_1
48
32
PB11
31
30
29
VSS_1
PB12
PB10
PA2
PB2
PB13
PB1
3.3V
C15
100nF
MIC_VDD
<Connectors>
49
PA14
PA15
52
PC11
PC10
53
54
55
PB3
PD2
PC12
58
57
60
56
PB4
PB5
PB7
PB6
59
62
63
61
PB8
BOOT0
PB9
PB14
PA1
2
L5
BEAD
VSS_3
PA0-WKUP
PB0
16
PB15
27
LED2
VDDA
28
15
PC6
17
1
C9
100nF
14
VSSA
26
C10
10uF
LED1
MIC_CK
PC7
PC5
L2
820nH
PC8
PC3
PC4
13
PC9
PC2
25
2
PC1
PA3
1
PA8
U5
24
12
PA9
PC0
PA7
11
NRST
PA6
10
FAIL
PA10
23
MUTE
PD1_OSC_OUT
22
9
PA11
PA5
8
STBY
PD0_OSC_IN
PA4
7
RESET
PA12
20
A_VDD
C4
100nF
PC15-OSC32_OUT
21
BUT1
TACT2
2
NRST
VDD_3
64
6
PA13
VDD_4
UC_OSC_OUT
VSS_2
PC14-OSC32_IN
VSS_4
2
UC_OSC_IN
5
VDD_2
PC13-TAMPER-RTC
19
4
R5
10K
VBAT
18
3
1
DocID024106 Rev 1
2
CLK
5
UC_VDD
JTCK
R17
1
LED3
LED2
LED1
UC_VDD
1
3
C23
100nF
U2
0R NS
C27
100nF
XT_ACTIVE
12.288_CK
MCO
C1
100nF
4
C24
10uF
MIC_VDD
SCL
JRST
1
MIC_VDD
SDA
2
UC_VDD
1
R13
MIC1CK
C31
18pF
STM32_I2S_LRCK
R33
10K
C18
4.7uF
CLK
MP34DB01
U10
Y1
12.288MHz
2
3
R21
C17
100nF
R34
1k
DATA
2
0R NS
1
D4
LED-1
1
STM32_I2S_DATA34
R40
2
D3
LED-1
2
R35
1k
2
1
D2
LED-1
U3
1
0R NS
1
2
1
2
2
UC_VDD
R32
100
4
MIC_DATA12
L/R
1
R31
100
UC_OSC_OUT
2
1
R30
100
1
VDD
1
R37
10k
UC_VDD UC_VDD
1
C2
18pF
UC_OSC_IN
1
3
GND
UC_VDD
C28
2.2uF
1
<Microphones>
MIC_VDD
1
5
UC_VDD
<Clock Generators>
U7
2
VSS_CAP
GND
<uController STM32>
AN4227
Figure 9. Board schematic (STM32 microcontroller, Mangusta option, clock generators, connectors, and microphones)
J9
CON4
R16
0R NS
MIC_DATA12
C11
100nF
C12
4.7uF
C14
4.7uF
C13
100nF
VSS_CAP
TP1
SPI1_Clock
2
1
R36
0R0
I2S_DAT_12
I2S_DAT_34
I2S_BICK
I2S_LRCK
2
2
0R0 R9
0R0 R7
1
1
0R0 R11
2
1
2
0R0 R10
1
STM32_I2S_DATA12
STM32_I2S_DATA34
STM32_I2S_BICK
STM32_I2S_LRCK
Schematics
10/13
AN4227
Appendix B
Layout
Layout
Figure 10. Board layout - top view
Figure 11. Board layout - bottom view
DocID024106 Rev 1
11/13
Revision history
3
AN4227
Revision history
Table 4. Document revision history
12/13
Date
Revision
22-Mar-2013
1
Changes
Initial release.
DocID024106 Rev 1
AN4227
Please Read Carefully:
Information in this document is provided solely in connection with ST products. STMicroelectronics NV and its subsidiaries (“ST”) reserve the
right to make changes, corrections, modifications or improvements, to this document, and the products and services described herein at any
time, without notice.
All ST products are sold pursuant to ST’s terms and conditions of sale.
Purchasers are solely responsible for the choice, selection and use of the ST products and services described herein, and ST assumes no
liability whatsoever relating to the choice, selection or use of the ST products and services described herein.
No license, express or implied, by estoppel or otherwise, to any intellectual property rights is granted under this document. If any part of this
document refers to any third party products or services it shall not be deemed a license grant by ST for the use of such third party products
or services, or any intellectual property contained therein or considered as a warranty covering the use in any manner whatsoever of such
third party products or services or any intellectual property contained therein.
UNLESS OTHERWISE SET FORTH IN ST’S TERMS AND CONDITIONS OF SALE ST DISCLAIMS ANY EXPRESS OR IMPLIED
WARRANTY WITH RESPECT TO THE USE AND/OR SALE OF ST PRODUCTS INCLUDING WITHOUT LIMITATION IMPLIED
WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE (AND THEIR EQUIVALENTS UNDER THE LAWS
OF ANY JURISDICTION), OR INFRINGEMENT OF ANY PATENT, COPYRIGHT OR OTHER INTELLECTUAL PROPERTY RIGHT.
ST PRODUCTS ARE NOT AUTHORIZED FOR USE IN WEAPONS. NOR ARE ST PRODUCTS DESIGNED OR AUTHORIZED FOR USE
IN: (A) SAFETY CRITICAL APPLICATIONS SUCH AS LIFE SUPPORTING, ACTIVE IMPLANTED DEVICES OR SYSTEMS WITH
PRODUCT FUNCTIONAL SAFETY REQUIREMENTS; (B) AERONAUTIC APPLICATIONS; (C) AUTOMOTIVE APPLICATIONS OR
ENVIRONMENTS, AND/OR (D) AEROSPACE APPLICATIONS OR ENVIRONMENTS. WHERE ST PRODUCTS ARE NOT DESIGNED
FOR SUCH USE, THE PURCHASER SHALL USE PRODUCTS AT PURCHASER’S SOLE RISK, EVEN IF ST HAS BEEN INFORMED IN
WRITING OF SUCH USAGE, UNLESS A PRODUCT IS EXPRESSLY DESIGNATED BY ST AS BEING INTENDED FOR “AUTOMOTIVE,
AUTOMOTIVE SAFETY OR MEDICAL” INDUSTRY DOMAINS ACCORDING TO ST PRODUCT DESIGN SPECIFICATIONS.
PRODUCTS FORMALLY ESCC, QML OR JAN QUALIFIED ARE DEEMED SUITABLE FOR USE IN AEROSPACE BY THE
CORRESPONDING GOVERNMENTAL AGENCY.
Resale of ST products with provisions different from the statements and/or technical features set forth in this document shall immediately void
any warranty granted by ST for the ST product or service described herein and shall not create or extend in any manner whatsoever, any
liability of ST.
ST and the ST logo are trademarks or registered trademarks of ST in various countries.
Information in this document supersedes and replaces all information previously supplied.
The ST logo is a registered trademark of STMicroelectronics. All other names are the property of their respective owners.
© 2013 STMicroelectronics - All rights reserved
STMicroelectronics group of companies
Australia - Belgium - Brazil - Canada - China - Czech Republic - Finland - France - Germany - Hong Kong - India - Israel - Italy - Japan Malaysia - Malta - Morocco - Philippines - Singapore - Spain - Sweden - Switzerland - United Kingdom - United States of America
www.st.com
DocID024106 Rev 1
13/13