AN13049

Wi-Fi/Bluetooth/802.15.4 M.2 Key E Pinout Definition
Rev. 4 — 30 May 2023

Application note

Document Information
Information

Content

Keywords

AN13049, Wi-Fi, Bluetooth, 802.15.4, M.2, Pinout, Tri-Radio

Abstract

This document defines M.2 usage for both NXP Wi-Fi/Bluetooth and Tri-Radio M.2 module design.

AN13049

NXP Semiconductors

Wi-Fi/Bluetooth/802.15.4 M.2 Key E Pinout Definition

1 Introduction
M.2 is a form factor for mobile adapters defined by the PCI-SIG (http://www.pcisig.com). The pinouts for M.2
sockets are defined in the PCI Express M.2 Specification.
M.2 sockets with mechanical Key E are used on platforms based on NXP MPUs and MCUs to support wirelessconnectivity modules based on NXP Wi-Fi/Bluetooth/802.15.4 radios.
Some of the signals defined in the pinout are used to connect optional sideband and debug signals used by
NXP Wi-Fi/Bluetooth/802.15.4 radios.
To ensure proper connection for the sideband and debug signals, this document defines the pin assignments forM.2 sockets (mechanical Key E) on platforms based on NXP MPUs and MCUs.
This document defines M.2 usage for both NXP Wi-Fi/Bluetooth and Tri-Radio M.2 module design.
Figure 1 shows NXP Single/Dual Radio M.2 interface block diagram.
Figure 2 shows NXP Tri-Radio M.2 interface block diagram. It must add SPI interface for 802.15.4 device, andadd an I/O expander to support sideband control signals.

PCIe

PCIe

SDIO

SDIO

UART

UART

PCM

I2S/PCMVEN DEF

Wi-Fi
BT

WL_WAKE_IN

PIN 40 (1.8V)

VEN DEF

BT_WAKE_IN

PIN 42 (1.8V)

E

Other Sideband Signals

Figure 1. NXP Single/Dual Radio M.2 interface block diagram

AN13049

Application note

All information provided in this document is subject to legal disclaimers.

Rev. 4 — 30 May 2023

© 2023 NXP B.V. All rights reserved.

2/8

AN13049

NXP Semiconductors

Wi-Fi/Bluetooth/802.15.4 M.2 Key E Pinout Definition

PCIe

PCIe

SDIO

SDIO

UART

UART

PCM

I2S/PCM
Bidirectional Buffer

VEN DEF/RSV

Wi-Fi
BT

SPI/UART2
SPI

PIN 38/40/42/64 (1.8V)#ALERT

SPI_INTPIN 62802.15.4

SPI_EN
RST_IND
I2C

I2C

E

PIN 58/60

I2C GPIOEXPANDER
EXPNDERIND_RST_15.4
WL_WAKE_IN
BT_15.4_WAKE_IN

Other Sideband Signals

Figure 2. NXP Tri-Radio M.2 interface block diagram

Before building your board, check the interface connector specification from the wireless module vendor toconfirm the pinout used by the module.
For the full definition of the socket pinout, see the PCI Express M.2 Specification, available from PCI-SIG
website (http://www.pcisig.com).
Note: All the pins that are not listed in this document are recommended to follow the PCI Express M.2 Type E
specification or should not be connected.

2 Usage signals for Wi-Fi/Bluetooth and Tri-RadioThis section describes the NXP defined sideband control and SPI signals between the NXP Radio module and
MPU/MCU.
Table 1 shows the pin assignments utilized for sideband and SPI signals.
Note: For details on the mandatory and optional lines, see the module data sheet.
Table 1. Sideband and SPI signals
Pin

PCIe M.2
Signal

20

UART_
WAKE#

AN13049

Application note

Type

[1]

I

Voltage Usage for NXP Single/Dual Radio Usage for NXP Tri-Radi
3.3 V

BT_WAKE_OUT:
Bluetooth radio to wake up the
MPU/MCU.
Active Low by default.

All information provided in this document is subject to legal disclaimers.

Rev. 4 — 30 May 2023

BT_15.4_WAKE_OUT:
Bluetooth radio to wake up the
MPU/MCU.
Active Low by default.
© 2023 NXP B.V. All rights reserved.

3/8

AN13049

NXP Semiconductors

Wi-Fi/Bluetooth/802.15.4 M.2 Key E Pinout Definition
Table 1. Sideband and SPI signals...continued
Pin

PCIe M.2
Signal

Type[1]

Voltage Usage for NXP Single/Dual Radio Usage for NXP Tri-Radi
Connect to MPU/MCU GPIO open- Connect to MPU/MCU GPIO opendrain. Pullup required on platform. drain. Pullup required on platform.

21

SDIO_WAKE#

I

1.8 V

WL_WAKE_OUT:
Same as single/dual radio.
Wi-Fi radio to wake up the MPU/
MCU.
Active Low by default.
Connect to MPU/MCU Open-drain.
Pullup required on platform.

23

SDIO_
RESET#O

1.8 V

IND_RST_WL:
Independent software reset for WiFi.
Active Low by default.
Connect to MPU/MCU GPIO.

Same as single/dual radio.

38

VENDOR
DEFINED

O

1.8 V

NC

SPI_TXD: SPI transmit signal.

40

VENDOR
DEFINED

I/O

1.8 V

WL_WAKE_IN:

SPI_RXD: SPI receive signal.
.

VENDOR
DEFINEDO

42

MPU/MCU to wake up the Wi-Fi
radio.
Active Low by default.
Connect to MPU/MCU GPIO.
1.8 V

BT_WAKE_IN:

SPI_CLK: SPI clock signal.

MPU/MCU to wake up theBluetooth radio.
Active Low by default.
Connect to MPU/MCU GPIO.

44

[2]

COEX3

I/O

1.8 V

Talk to NXP support team.

Same as single/dual radio.

46

[2]

COEX2

I

1.8 V

Talk to NXP support team.

Same as single/dual radio.

48

[2]

COEX1

O

1.8 V

Talk to NXP support team.

Same as single/dual radio.

54

W_
DISABLE2#

O

3.3 V

IND_RST_BT: Independent
software reset for Bluetooth.
Active Low by default Connect to
MPU/MCU GPIO.

Same as single/dual radio.

56

W_
DISABLE1#

O

3.3 V

PDn:

PDn:

Full power down for the Wi-Fi/
Bluetooth radio or controls the
PMIC ENABLE signal.
High = Normal
Low = Full Power-down mode
Connect to MPU/MCU GPIO.

Full power down for the Tri-radio or
controls the PMIC ENABLE signal.
High = Normal
Low = Full Power-down mode
Connect to MPU/MCU GPIO.

58

I2C_DATA

I/O

1.8 V

NC

I2C SDA:I2C data for I/O expander.
Open-drain. Pullup required on
platform. See Table 2.

60

I2C_CLK

O

1.8 V

NC

I2C SCL:

AN13049

Application note

All information provided in this document is subject to legal disclaimers.

Rev. 4 — 30 May 2023

© 2023 NXP B.V. All rights reserved.

4/8

AN13049

NXP Semiconductors

Wi-Fi/Bluetooth/802.15.4 M.2 Key E Pinout Definition
Table 1. Sideband and SPI signals...continued
Pin

PCIe M.2
Signal

Type[1]

Voltage Usage for NXP Single/Dual Radio Usage for NXP Tri-Radi
I2C clock from MPU/MCU for I/O
expander. See Table 2.

62

64

[3]

[1]

ALERT#

I

1.8 V

NC

SPI_INT:SPI interrupt signal.
Open-drain. Pullup required on
platform.

RESERVED

O

1.8 V

NC

SPI_FRM:
SPI frame signal.

Type refers to the signal direction:• Type O means signal is an output from the MPU/MCU to the adapter.
• Type I means that the signal is an input to the MPU/MCU from the adapter.
For future use, reserve the sideband signals of coexistence and audio trigger on the M.2 board.
• To avoid the potential risk on which 1.8 V is designed on other platform, optionally add a serial 100-1K ohm resistor on the path from SPI_FRM to M.2
PIN64.
• On the Tri-radio M.2 adapter side for the SPI signals, follow the SPI signal definitions based on M.2 Spec Rev 3.0 in the application note document. Do
not follow the M.2 Spec Rev 4.0 signal definitions.
• On the host side, the SPI signal definitions on M.2 connector should be consistent as mention in the application note document. Otherwise, the802.15.4 transceiver of Tri-radio M.2 adapter cannot work normally. However, this does not impact the Wi-Fi and Bluetooth of the Tri-radio adapter.

[2]
[3]

2.1 I2C I/O expander for sideband signals
For a Tri-Radio M.2 module, it uses an I2C expander to support sideband control signals. It is important to use
an NXP PCAL6408A part. It is an 8-bit general-purpose I/O expander that provides GPIO expansion via the I2C
bus interface. See the I/O expander port assignment or the sideband signals in Table 2.
Table 2. I/O expander function
SymbolType

VoltageNXP Usage

Description

P0

O

VIO

SPI Buffer enable

Enable SPI Buffer when Tri-radio is designed. Active
high by default.
Pull down required on M.2 board.

P1

O

VIO

IND_RST_15.4

Independent software reset for 802.15.4 radio. Active
low by default.

P2

O

VIO

WL_WAKE_IN

MPU/MCU to wake up the Wi-Fi radio. Active low by
default.

P3

O

VIO

BT_15.4_W AKE_IN

MPU/MCU to wake up the Bluetooth and 802.15.4
radio. Active low by default.

P4

I

VIO

RST_IND

Independent software reset indicator output signal to
host.

P5-P7

Reserved

Not used.
Recommend to add test pads on P5-P7.

3 Host and audio interfaces
The wireless connectivity module may support an audio interface.
1

The modules may also support various host interfaces including SDIO, UART , or PCI Express.
1 CTS and RTS flow control lines are requested for Bluetooth control.
AN13049

Application note

All information provided in this document is subject to legal disclaimers.

Rev. 4 — 30 May 2023

© 2023 NXP B.V. All rights reserved.

5/8

AN13049

NXP Semiconductors

Wi-Fi/Bluetooth/802.15.4 M.2 Key E Pinout Definition
For the pin assignments on these interfaces, see the PCI_Express_M.2_Spec document on http://
www.pcisig.com.

4 JTAG debug signals
The JTAG debug signals JTAG_TDI, JTAG_TDO, JTAG_TCK, and JTAG_TMS are used to support Softwaredevelopment. Keeping a JTAG connector (Hirose FH12-10S-0.5SH(55)) or test pads on the M.2 module isrecommended.

5 Revision history
Table 3 summarizes the changes to this document.
Table 3. Revision history
Revision
number

Date

Substantive changes

1

12 November 2020

Initial release.

2

16 September 2021

Updated Section 1 and Section 2.

3

17 January 2022

Added the usage for Tri-Radio design.
Removed the JTAG signals from the M.2 pins.

430 May 2023

Updated Section 2 and added Section 3.

AN13049

Application note

All information provided in this document is subject to legal disclaimers.

Rev. 4 — 30 May 2023

© 2023 NXP B.V. All rights reserved.

6/8

AN13049

NXP Semiconductors

Wi-Fi/Bluetooth/802.15.4 M.2 Key E Pinout Definition

6 Legal information
6.1 Definitions
Draft — A draft status on a document indicates that the content is still
under internal review and subject to formal approval, which may resultin modifications or additions. NXP Semiconductors does not give any
representations or warranties as to the accuracy or completeness of
information included in a draft version of a document and shall have noliability for the consequences of use of such information.

Export control — This document as well as the item(s) described herein
may be subject to export control regulations. Export might require a priorauthorization from competent authorities.

6.2 Disclaimers
Limited warranty and liability — Information in this document is believed
to be accurate and reliable. However, NXP Semiconductors does not give
any representations or warranties, expressed or implied, as to the accuracy
or completeness of such information and shall have no liability for theconsequences of use of such information. NXP Semiconductors takes noresponsibility for the content in this document if provided by an information
source outside of NXP Semiconductors.
In no event shall NXP Semiconductors be liable for any indirect, incidental,
punitive, special or consequential damages (including - without limitation lost profits, lost savings, business interruption, costs related to the removalor replacement of any products or rework charges) whether or not suchdamages are based on tort (including negligence), warranty, breach ofcontract or any other legal theory.
Notwithstanding any damages that customer might incur for any reason
whatsoever, NXP Semiconductors’ aggregate and cumulative liability
towards customer for the products described herein shall be limited inaccordance with the Terms and conditions of commercial sale of NXP
Semiconductors.
Right to make changes — NXP Semiconductors reserves the right tomake changes to information published in this document, including without
limitation specifications and product descriptions, at any time and without
notice. This document supersedes and replaces all information supplied prior
to the publication hereof.
Suitability for use — NXP Semiconductors products are not designed,
authorized or warranted to be suitable for use in life support, life-critical orsafety-critical systems or equipment, nor in applications where failure or
malfunction of an NXP Semiconductors product can reasonably be expected
to result in personal injury, death or severe property or environmental
damage. NXP Semiconductors and its suppliers accept no liability forinclusion and/or use of NXP Semiconductors products in such equipment orapplications and therefore such inclusion and/or use is at the customer’s own
risk.
Applications — Applications that are described herein for any of theseproducts are for illustrative purposes only. NXP Semiconductors makes norepresentation or warranty that such applications will be suitable for the
specified use without further testing or modification.
Customers are responsible for the design and operation of theirapplications and products using NXP Semiconductors products, and NXP
Semiconductors accepts no liability for any assistance with applications or
customer product design. It is customer’s sole responsibility to determine
whether the NXP Semiconductors product is suitable and fit for thecustomer’s applications and products planned, as well as for the planned
application and use of customer’s third party customer(s). Customers should
provide appropriate design and operating safeguards to minimize the risks
associated with their applications and products.
NXP Semiconductors does not accept any liability related to any default,
damage, costs or problem which is based on any weakness or default
in the customer’s applications or products, or the application or use bycustomer’s third party customer(s). Customer is responsible for doing allnecessary testing for the customer’s applications and products using NXP
Semiconductors products in order to avoid a default of the applications
and the products or of the application or use by customer’s third party
customer(s). NXP does not accept any liability in this respect.

AN13049

Application noteTerms and conditions of commercial sale — NXP Semiconductors
products are sold subject to the general terms and conditions of commercial
sale, as published at http://www.nxp.com/profile/terms, unless otherwise
agreed in a valid written individual agreement. In case an individual
agreement is concluded only the terms and conditions of the respective
agreement shall apply. NXP Semiconductors hereby expressly objects toapplying the customer’s general terms and conditions with regard to thepurchase of NXP Semiconductors products by customer.

Suitability for use in non-automotive qualified products — Unless
this data sheet expressly states that this specific NXP Semiconductors
product is automotive qualified, the product is not suitable for automotive
use. It is neither qualified nor tested in accordance with automotive testingor application requirements. NXP Semiconductors accepts no liability forinclusion and/or use of non-automotive qualified products in automotive
equipment or applications.
In the event that customer uses the product for design-in and use inautomotive applications to automotive specifications and standards,
customer (a) shall use the product without NXP Semiconductors’ warrantyof the product for such automotive applications, use and specifications, and(b) whenever customer uses the product for automotive applications beyond
NXP Semiconductors’ specifications such use shall be solely at customer’s
own risk, and (c) customer fully indemnifies NXP Semiconductors for any
liability, damages or failed product claims resulting from customer design anduse of the product for automotive applications beyond NXP Semiconductors’
standard warranty and NXP Semiconductors’ product specifications.
Translations — A non-English (translated) version of a document, including
the legal information in that document, is for reference only. The English
version shall prevail in case of any discrepancy between the translated andEnglish versions.
Security — Customer understands that all NXP products may be subject tounidentified vulnerabilities or may support established security standards or
specifications with known limitations. Customer is responsible for the designand operation of its applications and products throughout their lifecycles
to reduce the effect of these vulnerabilities on customer’s applications
and products. Customer’s responsibility also extends to other open and/or
proprietary technologies supported by NXP products for use in customer’s
applications. NXP accepts no liability for any vulnerability. Customer should
regularly check security updates from NXP and follow up appropriately.
Customer shall select products with security features that best meet rules,
regulations, and standards of the intended application and make theultimate design decisions regarding its products and is solely responsible
for compliance with all legal, regulatory, and security related requirements
concerning its products, regardless of any information or support that may beprovided by NXP.
NXP has a Product Security Incident Response Team (PSIRT) (reachable
at PSIRT@nxp.com) that manages the investigation, reporting, and solution
release to security vulnerabilities of NXP products.
NXP B.V. - NXP B.V. is not an operating company and it does not distributeor sell products.

6.3 Trademarks
Notice: All referenced brands, product names, service names, andtrademarks are the property of their respective owners.
NXP — wordmark and logo are trademarks of NXP B.V.
Bluetooth — the Bluetooth wordmark and logos are registered trademarks
owned by Bluetooth SIG, Inc. and any use of such marks by NXP
Semiconductors is under license.

All information provided in this document is subject to legal disclaimers.

Rev. 4 — 30 May 2023

© 2023 NXP B.V. All rights reserved.

7/8

AN13049

NXP Semiconductors

Wi-Fi/Bluetooth/802.15.4 M.2 Key E Pinout Definition

Contents
1
2
2.1
3
4
5
6

Introduction ......................................................... 2
Usage signals for Wi-Fi/Bluetooth and TriRadio .................................................................... 3
I2C I/O expander for sideband signals .............. 5
Host and audio interfaces .................................. 5
JTAG debug signals ........................................... 6
Revision history .................................................. 6
Legal information ................................................ 7

Please be aware that important notices concerning this document and the product(s)described herein, have been included in section 'Legal information'.

© 2023 NXP B.V.

All rights reserved.

For more information, please visit: http://www.nxp.com
Date of release: 30 May 2023
Document identifier: AN13049