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RoadTest: Integrating NFC with the NXP PN7150

Author: cjsieh

Creation date: 23 Apr 2019

Evaluation Type: Development Boards & Tools

Did you receive all parts the manufacturer stated would be included in the package?: True

What other parts do you consider comparable to this product?:

What were the biggest problems encountered?: The version of the FRDM-K41Z board provided uses the IRQ and VEN Arduino pinout also for the SWD Debug interface. This makes the pn7150 Arduino board incompatible with the FRDM-K41Z unless jumper wires are used instead of mounting in on top. Software changes were then needed to indicate what CPU pin the IRQ and VEN pins moved to.

Detailed Review:

Review of the NXP PN7150

PROPOSAL

In my proposal for this review I suggested replacing the RFID RC522 Reader with the PN7150 from a previously built RFID scanner.  This RFID scanner reads  MiFare Tags and publishes the UID data from the tag to a MQTT Broker via a WiFi connected ESP32.  A Google AIY Voice Kit(Raspberry Pi based) subscribed to the MQTT UID data and would "SAY" the UID data.

RC522 RFID Scanner to MQTT Broker

I also proposed that I research the use of the PN7150 with a Raspberry Pi.

The Data Flow

RESULTS with ESP32

Basic NXP PN7150 Functionality with MCUXpresso PN7150 Example Code

I was able to replace the 522 RFID reader with the PN7150.  This required the software provided in SW4325 as described in PN7150 Application Note 11990  MCUXpresso Examples be ported to the ESP32.  The basis was the bare metal version intended for the OM13058 LPC11U68 as described in Section 2.3 .  In Section 6.1 and 6.2 it describes  how I2C and GPIO is used .   I provided equivalent Arduino IDE ESP32 functions to all of the calls to I2C  and GPIO code as used in the TML as described in section 5.3  .  I provided replacement headers files for the hardware definitions of the IRQ and VEN GPIO locations .  The following functions were replaced with code for  ESP32.  All of these were calls to the Hardware of the LPC11U68 originally.

• i2c_Write
• i2c_Read
• i2c_begin
• gpio_GetValue
• gpio_SetValue
• gpio_SetDir

Thus I did not have to change any of the NXP code.

Adding MQTT Functionality to MCUXpresso PN7150 Example Code

Since I was learning about NFC I wanted to know more about NTAG's .  My research showed that it was very easy to add "data" to a NTAG as NDEF records  using the NXP TagWriter Android App.  The NFC Data Exchange Format (NDEF) is a standardized data format that can be used to exchange information between any compatible NFC device and another NFC device or tag .  I decided to add NDEF Text records to my NTAG's and send this to the MQTT Broker.   Google AIY Voice Kit would then "SAY" the NDEF Text that it received via MQTT.

MQTT is a publish-subscribe messaging protocol.  It is designed for connections with remote locations where a "small code footprint" is required or the network bandwidth is limited.  It is very popular in the IOT community.

To implement MQTT with the PN7150 I had to add a call to my  "MQTT code"  after the NXP code had determined that the NDEF record was of type Text.  All other NDEF records were just printed to the serial port as the original NXP code did.

The following video shows a PN7150 reading  NTAG216, NTAG215 and NXP LPC8N04 M0/NTAG chip and sending the NDEF Text record to a MQTT Broker via a ESP32.  A Google AIY Voice Kit then uses text to voice technology to "SAY" the Text.

I am very impressed with the LPC8N04 ,  it is a M0 Microprocessor and a NTAG on the same chip.  I obtained it at a "NXP Technology Days" exhibit from Future Electronics.  Since it is just a NTAG the PN7150 can read the data on it just fine.

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One thing that the PN7150 did that was better than the 522 was that the distance that was needed for a good scan was  farther away than the 522.  The 522 you had to touch the tag to the 522.  With the PN7150 i could be much farther away.

FINAL SUMMARY

I got the PN7150 to work with the ESP32 and a Raspberry Pi Zero W and send NDEF Text data to a MQTT Broker where a Google AIY Voice Kit would "SAY" the NDEF Text.

I sure learned a lot about NTAG's and NDEF Text records and how easy they are to to write.  The Linux Demo App can also write NTAG's NDEF Records.

I did not know that there are Dynamic NTAG's where a Micro can change the contents of the NTAG on the fly.  I see this as a very powerful technology.

RESEARCH

Provided Hardware from Element14/NXP

     PN7150 Arduino OM5578

     FRDM-KW41Z kit

I started this research with getting the  work with the software described in  OM5578 Application Note 11841 .  To do this I needed one of the supported development boards.  Choices from Section 3 show  OM13071, OM13074 or OM13058 or FRDM-K64F.  I already had a FRDM-K64F so used that first.

NXP FRDM-K64F

• Worked out of box.  Was very happy.
• Was not familiar with the MCUXpresso IDE so first installed and tested some of the examples
  • NXP-NCI MCUXpresso Example Software Application Note  11990

• Installed the SW4325 PN7150 Example Software
  • NXP-NCI MCUXpresso Example Software SW4325 Download

NXP FRDM-KW41Z

• This board was NOT one of the boards mentioned in Section 3 of OM5578 Application Note 11841 mentioned above.  That was not expected since these boards were provided with the Road Test .
  • Found a port of the Example software at
  • FRDM-KW41Z PN7150 Community software example
  • This software did NOT work.  Bummer.

• Conflict of Arduino Pinout of OM5578 board vs provided  Rev A3 FRDM-KW41Z board
• Pin IRQ and Pin VEN conflict with SWD Debug Pinout
• Community Software Web page did mention that it needed a Rev B1
• Took quite a bit of time to determine that problem was a because of A3 board since documentation made it hard to determine what Rev board we had
• Had to change which pin IRQ and VEN were connected to on the FRDM-KW41Z via jumper wires instead of plugging the PN7150 into the FRDM-KW41Z board
• This required a 1 line software change to the Community software example
• See below for details

FRDM-KW41Z Hardware Pinout

Raspberry Pi Zero W

Raspberry Pi Hardware Pinout

Raspberry Pi Software

I used the PN71xx Linux Software Stack Integration Guidelines AN11697 on how to use the Raspberry Pi with the PN7150.  There were 3 options for building the software

• pn5xx_i2c
  • kernel driver
  • need to build new kernel
• alt
  • sys/class/gpio
  • /dev/i2c-dev
• LPCUSBSIO
  • USB HID interface

I used option "alt" for building the software.   I picked the "easiest" choice as I did not want to rebuild a kernel and there was not much documentation on how to use LPCUSBSIO.   I had to enable the I2C option in /boot/config using " sudo raspi-config" . 

This software worked just fine.

I added MQTT support to the Demo App provided at  https://github.com/NXPNFCLinux/linux_libnfc-nci/tree/master/demoapp

There is also a Raspberry Pi "image" which I did not try.  I wanted to find out how hard it was to build the PN7150 library and Demo App.  The documentation in AN11697 provide enough detail.  You just have to read it very carefully as they clearly added changes later that might seem out of place.

ESP32 LolinD32

LolinD32 Hardware Pinout

• Pull up resisters needed on I2C SCL and I2c SDA since they are NOT provided on ESP32 LolinD32 board or OM5578 board

ESP32 LolinD32 Software

I ported the MCUXpresso PN7150 Example software for the LPC11U68 over to the ESP32 Arduino IDE.  I added replacement functions for the I2C and GPIO routines used in the MCUXpresso PN7150 Example code.  See above for more details. I added my MQTT code from my original 522 RFID Scanner.

REFERENCE DOCUMENTS

• OM5578 Development Kit
• PN7150 NFC Controller SBC Kit User Manual
• OM29110 NFC's SBC Interface Boards User Manual
• PN7150 Arduino SBC Kit Quick Start Guide
• PN7150 Raspberry Pi SBC Quick Start Guide
• PN7150 Data Sheet
• PN7150 User Manual