NXP Semiconductors FRDM-KW41Z User guide

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Start-up Guide for FRDM-KW41Z Evaluation Board Bluetooth
Paring example with NTAG I²C plus
Rev. 2.0 — 5 June 2018
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Document information
Info
Content
Keywords
NTAG I²C plus, FRDM-KW41Z
Abstract
This document gives a start-up guide for Bluetooth BLE pairing
demonstration between FRDM-KW41 and NFC mobile device with use of
NTAG I²C plus and also explains how the pairing part is included in the
connectivity stack.

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Contact information
For more information, please visit:
http://www.nxp.com
Revision history
Rev
Date
Description
2.0
20180605
The BT pairing was updated with a different demo application and migrated from Kinetis
Design Studio to MCUXpresso IDE and SDK.
1.2
20180206
Change of the information on how to use the demo in chapter 2
1.1
20170307
Text: LPCXpresso IDE changed to Kinetis Design Studio IDE
1.0
20170307
Initial version

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1. Introduction and HW setup
This document can be divided into three basic parts. This the first one introduces and
describes the HW setting. The second part is a quick startup guide and describes how to
quickly and easily work with the prepared sample of the Bluetooth demo application. The
third part of the document describes how to import NTAG I2C middleware with a NDEF
library into the selected Bluetooth application.
The whole integration process of the NTAG I2C middleware and the NDEF library can be
applied to any customer application.
1.1 HW setup
For the NTAG I2C plus development kit, there are 2 kits that can be attached to the
FRDM-KW41Z board. The first OM5569 [2] is the original and it represents the typical
HW design, the second OM23221ARD [3] is adapted to Arduino pinout. Both kits are fully
fledged and its on the user which is chosen.
1.1.1 NTAG I2C plus board
The HW connection and wiring between the NTAG I2C plus board and FRDM-KW41Z
board is shown at the following picture. RGB LED and micro switches SW3, SW4 which
are used in HID_device demo application (more information is in the chapter 2.2) and
which signal usage of the NTAG I2C chip are mounted directly on the FRDM-KW41Z.
Setting functions and control functions for this LED is a part of the SDK. From this reason
there is not required extra HW setup for these elements (see reference[2]).
Fig 1. HW connection with the NTAG I2C plus board (OM5569)

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Table 1. HW configuration within the integration of the NTAG I2C plus PCB board
Example
Description
GPIO
GPIO direction
specification
I2C – SCL
Interface clock
PTC 2
I2C specific
open drain SCL
I2C – SDA
Interface data
PTC 3
I2C specific
open drain SCL
GND
Ground
GND
output
-
VCC_SW
NTAG I2C Antenna
board power supply
P3V3
output
-
LED – RED
FRDM-KW41Z -
RGB LED driver
PTC 1
output
Default SDK
configuration
LED – GREEN
FRDM-KW41Z
RGB LED driver
PTA 19
output
Default SDK
configuration
LED – BLUE
FRDM-KW41Z
RGB LED driver
PTA 18
output
Default SDK
configuration
SW3
PTC 4
input
Default SDK
configuration
SW4
PTC 5
input
Default SDK
configuration
1.1.2 Arduino NTAG I2C plus board
OM23221ARD development kit with NTAG I²C plus is an easy add-on to many popular
MCU boards. It gives connectivity to any device with Arduino pinout. The HW setting is
the identical with previous description in the chapter 1.1.1 (see reference [3])
Fig 2. HW connection with the Arduino NTAG I2C plus board (OM23221ARD)

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2. Quick start-up the demo application
This chapter provides a procedure how to easily install the development environment
with the necessary components. Next, how to compile and debug a demo application and
finally how to verify it's functionality.
2.1 Installation of the MCUXpresso IDE and SDK
The whole project of the demo application is written for the MCUXpresso IDE, so it is
necessary to install this development environment. The next step is to generate and
import the SDK (Software Development Kit) needed for the application to be compiled
and debugged. The procedure to achieve this is described in the following chapters.
2.1.1 How to download the installation file of the MCUXpresso IDE
The following steps show how to easily download the installation file for the MCUXpresso
IDE.
1.) Open the welcome page of the MCUXpresso site [4]:
https://mcuxpresso.nxp.com/en/welcome
2.) Select the “SOFTWARE AND TOOLS” and press the “Learn More >”
Fig 3. MCUXpresso SDK builder – software tools

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3.) In the next step you will be redirected to the NXP web page
4.) Choose the “DOWNLOADS” tab and press the “Download”
Fig 4. IDE – starting the download
5.) Within the next step is necessary to sign in.
6.) Select the version of the installation file for MCUXpresso. It is recommended to
select the latest version (especially at the start of development) because it
contains the latest updates.
Fig 5. IDE – select a version

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7.) Select the correct type of the operating system that is used by user and
download the installation file.
Fig 6. IDE – select and download
2.1.2 Installation of the MCUXpresso IDE
The installation file was obtained using the procedure in the previous chapter 2.1.1. Once
it is started, it is recommended that user follows the standard recommended installation
setup. Custom installation requires a deeper knowledge of the MCUXpresso IDE.
No additional licenses are required after installing MCUXpresso. The development
environment can be used immediately in its entirety.
2.1.3 How to generate MCUXpresso SDK with Bluetooth and NTAG I2C software
From the reason the ntag_i2c_plus middleware (which covers the NTAG I2C chip
functionality) is missing in the general SDK here is the procedure how to generate the
SDK based on the necessary parts for the Bluetooth demo applications and
ntag_i2c_plus middleware software. Follow the steps bellow.

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1.) Open the welcome page of the MCUXpresso site [4]:
https://mcuxpresso.nxp.com/en/welcome
2.) Select the configurator based the board selection.
Fig 7. MCUXpresso SDK builder – board selection
3.) Sign in to the web page – it is necessary step
Fig 8. MCUXpresso login page

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4.) Enter the keyword “FRDM-KW41Z“ and configure the SDK
Fig 9. KW41Z board selection
5.) Select the SDK components
Fig 10. SDK components selection

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6.) Verify and start SDK building
Fig 11. SDK creating
7.) Download the SDK
Fig 12. SDK downloading
2.1.4 Importing the SDK to the MCUXpresso IDE
The final step that needs to be implemented to achieve a fully functional development
environment is importing the SDK. This step is very simple and it is done in a drag and
drop way. The following procedure shows how to import SDK.
1.) Launch the MCUXpresso IDE and select the workspace via the occurred popup
window.
2.) Switch window to the “Installed SDKs” and via drag & drop technique install the
downloaded SDK (see figure Fig 13).

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Fig 13. SDK installing to the MCUXpresso
2.2 How to show the demo
2.2.1 HID Demo from website
A ready-made version of the HID_device demo application is available on NXP website.
The application consists of integrated ntag_i2c_plus middleware and already supports
the BT pairing.
This sample project can be directly imported into MCUXpresso as an archived project. In
the following chapter is the procedure how to debug this prepared project.
2.2.1.1 MCUXpresso and FRDM-KW41Z SDK
It is necessary to install the MCUXpresso, generate the FRDM-KW41Z SDK and import
the SDK to MCUXpresso in accordance the chapter 2.1.
2.2.1.2 Importing of Archived Project
The archived project is packaged in the ZIP format. This project is then imported through
the "Quickstart menu" and then "Import project(s) from file system..." (see Fig 14).
Fig 14. Setting the archived project

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Find the archived project and continue importing. Project is automatically copied to the
workspace.
Fig 15. Importing of archived project
2.2.2 Demo running/debugging
Debug the application by clicking on the “Quickstart Panel” from the MCUXpresso on
“Debug ’hid_device_frdmkw41z_freertos”. Accept the popup window of the J-link term of
use.
Fig 16. Demo compiling-flashing-debugging

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The debugging starts via pressing the F8 on the keyboard (main menu tabs “Run-
>Resume”), see the Fig 17.
On the FRDM-KW41Z board, the white LED shall be blinking, notifying that the
application is running and is in the standby mode.
Fig 17. Start debugging
2.2.3 Behavior of the demo
By pressing the SW4 button for the first time after startup (now the red LED on KW41Z
board is blinking). After all this the application is ready for usage or testing.
The following states describe the behavior of the HID_device demo application:
•SW3 button pushed and phone is presented to the board:
The FRDM-KW41Z is paired over NFC automatically to the mobile phone.
Depending on the version of Android, the application of FRDM-KW41Z is
automatically connected and this is demonstrated by a moving cursor on your
phone. For some versions of Android, it is needed to go into settings menu, BT-
connections and tab on the paired BT-device. Then the connection to the
application is finally performed.
NOTE: This step was typically implemented from the mobile manufacturer as
they wanted the user to define what the application is allowed to do.
•SW4 button pushed and phone is presented to the board:
The NTAG I²C plus chip has now the URL of the NTAG I2C demo app written in an
NDEF container. It automatically opens up either playstore or the app on the
phone.

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3. How to add NTAG I2C to the HID_device demo project
For using the NTAG I2C chip the ntag_i2c_plus middleware package should be added to
the HID Bluetooth demo application. In the next chapters there is procedure how to add
the ntag_i2c_plus middleware to the FRDM-KW41Z demo application.
3.1.1 HID_device – The demo application
The demo application, which we took as a basis for adding NTAG I2C is hid_device. This
demo is based on operation system FreeRTOS or like “bare metal” (without operation
system). We will take the version with the FreeRTOS. The demo shows a moving arrow
on the smart phone display.
3.1.2 Import the HID_device demo application
The HID_device demo application is imported from the SDK. This step assumes that the
MCUXpresso and SDK are installed in accordance with chapter 2.1. Then import the
project will be done in the following steps.
1.) In the “Quickstart menu” click the “Import SDK example(s)…”. The “SDK Import
Wizard” window is open. Select the required SKD (frdmkw41z) and press
“Next”.
Fig 18. SDK selection
2.) In the “Examples” window search the “wireless_examples” and then
“bluetooth” directory (see Fig 19).

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Fig 19. Finding the required project
3.) Then search “hid_device” demo application and select the freeRTOS version
only.
4.) Press the “Finish” button and the project should be imported.
Fig 20. Importing the required project

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3.1.3 “ntag_i2c_plus” middleware
The procedure how to add the NTAG middleware package is universal for all demo
applications which supports FRDM-KW41Z development board. The name of the
middleware package for NTAG I2C chip is ntag_i2c_plus and the actual version has the
extension ntag_i2c_plus_1.0.0. It contains whole support software for NTAG I2C chip.
The directory with middleware should be located at following directory path, directly in the
SDK zip file:
SDK_2.2_FRDM-KW41Z.zip\middleware\ntag_i2c_plus_1.0.0
The internal structure of middleware should has following structure:
Fig 21. File structure of the ntag_i2c_plus_1.0.0
3.1.4 How to add the ntag_i2c_plus middleware to the Bluetooth demo
To have a HW support of the NTAG middleware SW there is necessary to add following
to the Bluetooth demo application:
•setting for GPIO pins for communication interface I2C
•add the NTAG software handler declaration in to the application source C file
•implement the NTAG timer
•add #includes to the C sources of the BT demo application
NOTE: Parts of C code which have been added for support the NTAG I2C chip are
separated by following conditional define:
#ifdef NTAG_I2C
#endif //NTAG_I2C
or following comment is added behind the C code, at the end of the line
#include "fsl_common.h" // added for NTAG middleware
3.1.4.1 GPIO pins setting
The NTAG I2C chip has, in addition to I2C pins, field detection (FD pin) and voltage out
(Vout pin - energy harvesting). Only I2C bus is used to connect the NTAG I2C chip to the
FRDM-KW41Z development kit. Other pins will remain unoccupied.
I2C pins

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GPIO pins of the I2C interface are generally defined in the pin_mux.c file in the function
BOARD_InitI2C(void) and should not be redefined in another location. GPIO pins for
both I2C interfaces (I2C0 or I2C1) are set to I2C mode within this function.
3.1.4.2 NTAG SW and HW initialization
SW and HW initialization is called in the main_task() function in the ApplMain.c file.
First the HW initialization is performed by the function hardware_init() and there
should be added following C-code, bellow the initialization DCDC module:
/* Init DCDC module */
BOARD_DCDCInit();
#ifdef NTAG_I2C
/* Init I2C pins for NTAG communication */
BOARD_InitI2C();
#endif // NTAG_I2C
Second is the SW initialization performed by function HAL_I2C_InitDevice() and
NTAG I2Chandler (ntag_handle) is filled by the NFC_InitDevice() function.
At the following C-code lines the SW initialization have to put before application thread
calling (App_Thread()) in main_task() function.
#ifdef NTAG_I2C
/* Initialize I2C for NTAG communication */
HAL_I2C_InitDevice(HAL_I2C_INIT_DEFAULT, I2C_MASTER_CLK_SRC,
NTAG_I2C_MASTER_BASEADDR);
SystemCoreClockUpdate();
/* Initialize the NTAG I2C components */
ntag_handle = NFC_InitDevice((NTAG_ID_T)0, NTAG_I2C_MASTER_BASEADDR);
#endif // NTAG_I2C
}
/* Call application task */
App_Thread( param );
}
The last step will be to insert the ntag_handle declaration at the beginning of the
ApplMain.c file.
/**********************************************************************
* Public memory declarations
**********************************************************************/
#ifdef NTAG_I2C
NFC_HANDLE_T ntag_handle; // NTAG handle
#endif // NTAG_I2C

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3.1.4.3 Added #includes to the BLE demo application
Using the “ntag_i2c_plus” middleware requires include of headers into BLE demo
application source code. Here is the list of files which require to include new headers:
ApplMain.c
#ifdef NTAG_I2C
/* NTAG middleware module */
#include "HAL_I2C_driver.h"
#include "app_ntag.h"
#endif //NTAG_I2C
hid_device.c
#ifdef NTAG_I2C
/* NTAG handler */
#include "app_ntag.h"
#endif //NTAG_I2C
3.1.4.4 Added new application NTAG files
There were created 2 application files (app_ntag.c and app_ntag.h) that creates an
interface between NTAG middleware SW and common demo application.
The app_ntag.c source file contains sample functions for working with NDEF
messages. Function NFC_MsgWrite() creates and writes the NDEF message in the
Type-2 Tag format to the NTAG I2C chip through the ntag_i2c_plus middleware. The
write algorithm is NFC-Forum compliance. Function NDEF_Pairing_Write() contains
a procedure to create a BTSSP record via using the NDEF library. The same is
performing function NDEF_Demo_Write() function. Here is shown how to create NDEF
multi-record that contains several types of NDEF records.
The app_ntag.h header file contains predefined blocks of constants (constant fields of
data) that are written to the NTAG I2C chip by default during the communication which
requires set the default content to the chip’s registers or erase the NTAG I2C chip user
memory and registers of lock bytes.
3.1.5 BLE Demo Application Extension
The body and state machine of the HID_device demo application is in the
hid_device.c file. Its extension for BLE pairing and writing NDEF messages to NTAG
I2C chip is added to the function BleApp_HandleKeys().This is because the writing
of NDEF messages is done by pressing microswitch SW3 and SW4.
3.1.5.1 NDEF Timer
Within the extension of the HID_device demo application there was necessary to create
NDEF timer. This one performs the time counter from the moment when SW3 or SW4
button is pressed. The timer counter is set to 2 seconds. During this time, it is indicated
to write the NDEF administration to the NTAG I2C chip. The timer has no other function.
To add the timer, it is necessary to add the following C-code to the hid_device.c file:
Add the declaration of the timer handler
This declaration is placed at the beginning to the hid_device.c file in to the part
“Private memory declarations”.
/************************************************************************************
* Private memory declarations

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************************************************************************************/
#ifdef NTAG_I2C
static tmrTimerID_t mNDEFTimerId;
static bool boNDEFState = FALSE;
#endif
Add the declaration of the timer callback function
NDEF timer callback function declaration is placed to the part “Private functions
prototypes”.
/************************************************************************************
* Private functions prototypes
************************************************************************************/
#ifdef NTAG_I2C
static void NDEFTimerCallback(void *);
#endif
Allocate / Initialize the timer
There are 3 timers used within the HID_device demo application. The NDEF timer is also
necessary to allocate in the function BleApp_Config() in the hid_device.c file, at
the same place as the common timers are allocated. Function TMR_AllocateTimer()
returns timer ID value which is stored in the variable mNDEFTimerId. The timer ID
allocation must be added behind the other timer as it is done at following C-code printout
/* Allocate application timers */
mAdvTimerId = TMR_AllocateTimer();
mHidDemoTimerId = TMR_AllocateTimer();
mBatteryMeasurementTimerId = TMR_AllocateTimer();
#ifdef NTAG_I2C
mNDEFTimerId = TMR_AllocateTimer();
#endif
Add the timer callback function
There is necessary add the NDEFTimerCallback() function at the end of the
hid_device.c file. If NDEF timer counter expires timer is stop. Then RGB LED is
switched off. There is the printout of the call back function at the following lines.
#ifdef NTAG_I2C
/*! *********************************************************************************
* \brief Handles timer callback for writing NDEF messages
*
* \param[in] pParam callback parameters.
*
********************************************************************************** */
static void NDEFTimerCallback(void * pParam)
{
/* Stop Advertising Timer */
TMR_StopTimer(mNDEFTimerId);
/* switch off the LED indication */
TurnOffLeds ();
}
#endif // NTAG_I2C

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3.1.6 Security change
The sample project for adding NTAG I2C middleware is hid_device and is described in
chapter 3.1.1. This project requires to enter the password “999999” during the Bluetooth
pairing. From this reason is necessary to degrease the security level to remove the
password sequence.
Security level is a part of the configuration and is set in the app_config.c file. In this file
following parameter must be changed
gSecurityMode_1_Level_3_c
to the new parameter
gSecurityMode_1_Level_1_c
Parameter gSecurityMode_1_Level_3_c is used on several places within the
app_config.c file. Use the FIND function (short key is “CTRL+F”) of the KDS IDE to find it
and update.
There are last two parameters of the gPairingParameters structure which are
necessary to change.
parameter:
.securityModeAndLevel = gSecurityMode_1_Level_3_c,
has to be changed to:
.securityModeAndLevel = gSecurityMode_1_Level_1_c,
parameter:
.localIoCapabilities = gIoDisplayOnly_c,
has to be changed to:
.localIoCapabilities = gIoNone_c,
parameter
.leSecureConnectionSupported = TRUE,
has to be changed to
.leSecureConnectionSupported = FALSE,