Azure IOT Hub nRF24L01 Windows 10 IoT Core Field Gateway with BorosRF2

A couple of BorosRF2 Dual nRF24L01 Hats arrived earlier in the week. After some testing with my nRF24L01 Test application I have added compile-time configuration options for the two nRF24L01 sockets to my Azure IoT Hub nRF24L01 Field Gateway.

Boros RF2 with Dual nRF24L01 devices
public sealed class StartupTask : IBackgroundTask
{
   private const string ConfigurationFilename = "config.json";

   private const byte MessageHeaderPosition = 0;
   private const byte MessageHeaderLength = 1;

   // nRF24 Hardware interface configuration
#if CEECH_NRF24L01P_SHIELD
   private const byte RF24ModuleChipEnablePin = 25;
   private const byte RF24ModuleChipSelectPin = 0;
   private const byte RF24ModuleInterruptPin = 17;
#endif

#if BOROS_RF2_SHIELD_RADIO_0
   private const byte RF24ModuleChipEnablePin = 24;
   private const byte RF24ModuleChipSelectPin = 0;
   private const byte RF24ModuleInterruptPin = 27;
#endif

#if BOROS_RF2_SHIELD_RADIO_1
   private const byte RF24ModuleChipEnablePin = 25;
   private const byte RF24ModuleChipSelectPin = 1;
   private const byte RF24ModuleInterruptPin = 22;
#endif

private readonly LoggingChannel logging = new LoggingChannel("devMobile Azure IotHub nRF24L01 Field Gateway", null, new Guid("4bd2826e-54a1-4ba9-bf63-92b73ea1ac4a"));
private readonly RF24 rf24 = new RF24();

This version supports one nRF24L01 device socket active at a time.

Enabling both nRF24L01 device sockets broke outbound message routing in a prototype branch with cloud to device(C2D) messaging support. This functionality is part of an Over The Air(OTA) device provisioning implementation I’m working o.

Adafruit.IO nRF24L01 Windows 10 IoT Core Field Gateway with BorosRF2

A couple of BorosRF2 Dual nRF24L01 Hats arrived earlier in the week. After some testing with my nRF24L01 Test application I have added compile-time configuration options for the two nRF24L01 sockets to my Adafruit.IO nRF24L01 Field Gateway.

Boros RF2 with Dual nRF24L01 devices
public sealed class StartupTask : IBackgroundTask
{
   private const string ConfigurationFilename = "config.json";

   private const byte MessageHeaderPosition = 0;
   private const byte MessageHeaderLength = 1;

   // nRF24 Hardware interface configuration
#if CEECH_NRF24L01P_SHIELD
   private const byte RF24ModuleChipEnablePin = 25;
   private const byte RF24ModuleChipSelectPin = 0;
   private const byte RF24ModuleInterruptPin = 17;
#endif

#if BOROS_RF2_SHIELD_RADIO_0
   private const byte RF24ModuleChipEnablePin = 24;
   private const byte RF24ModuleChipSelectPin = 0;
   private const byte RF24ModuleInterruptPin = 27;
#endif

#if BOROS_RF2_SHIELD_RADIO_1
   private const byte RF24ModuleChipEnablePin = 25;
   private const byte RF24ModuleChipSelectPin = 1;
   private const byte RF24ModuleInterruptPin = 22;
#endif

private readonly LoggingChannel loggingChannel = new LoggingChannel("devMobile AdaFruit.IO nRF24L01 Field Gateway", null, new Guid("4bd2826e-54a1-4ba9-bf63-92b73ea1ac4a"));
private readonly RF24 rf24 = new RF24();

For this initial version only one nRF24L01 device socket active at a time is supported.

Windows 10 IoT Core BorosRf2 – Dual nRF24L01 pHat/Hat

I have a couple of nRF24L01P Raspberry PI projects (primarily my Adafruit.IO and Azure IoT Hubs/Central Windows 10 IoT Core telemetry field gateways) and recently Boros Lab a vendor of suitable Raspberry PI Hats opened a store on Tindie.com.

I ordered a couple of BorosRf2 – Dual nRF24L01 pHat/Hat + RTC for Pis (mine were without the Real-time clock(RTC)) for testing. The vendor’s github repository had details of the GPIO pins used so it was relatively quick and easy to modify my Windows 10 IoT nRF24L01 test harness to work with a single port on the hat.

Single port configuration

By setting a conditional compile option (CEECH_NRF24L01P_SHIELD, BOROS_RF2_SHIELD_RADIO_0 or BOROS_RF2_SHIELD_RADIO_1) my test application could be configured to support the Boros or Ceech (with a modification detailed here) shields.

namespace devmobile.IoTCore.nRF24L01BackGroundTask
{
	public sealed class StartupTask : IBackgroundTask
	{
		// nRF24 Hardware interface configuration
#if CEECH_NRF24L01P_SHIELD
      private const byte ChipEnablePin = 25;
      private const byte ChipSelectPin = 0;
      private const byte InterruptPin = 17;
#endif
#if BOROS_RF2_SHIELD_RADIO_0
      private const byte ChipEnablePin = 24;
      private const byte ChipSelectPin = 0;
      private const byte InterruptPin = 27;
#endif
#if BOROS_RF2_SHIELD_RADIO_1
      private const byte ChipEnablePin = 25;
      private const byte ChipSelectPin = 1;
      private const byte InterruptPin = 22;
#endif
      private const string BaseStationAddress = "Node1";
      private const byte nRF24Channel = 20;
      private RF24 Radio = new RF24();
      private BackgroundTaskDeferral deferral;
      private ThreadPoolTimer timer;


Both vendors’ shields worked well with my test application, the ceech shield (USD9.90 April 2019) is a little bit cheaper, but the Boros shield (USD15.90 April 2019 ) doesn’t require any modification and has a socket for a second nRF24 device.

Easy Sensors Wireless field gateway Arduino Nano client

After not much development on my nrf24L01 AdaFruit.IO and Azure IOT Hub field gateways for a while some new nRF24L01 devices arrived in the post last week.

This sample client is an Arduino Nano clone with an Arduino Nano radio shield for NRF24L01+.

I use the shield’s onboard SHA204A crypto and authentication chip, and a Seeedstudio Temperature & Humidity sensor with the data uploaded to adafruit.io.

/*
  Copyright ® 2018 September devMobile Software, All Rights Reserved

  THIS CODE AND INFORMATION IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY
  KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
  IMPLIED WARRANTIES OF MERCHANTABILITY AND/OR FITNESS FOR A PARTICULAR
  PURPOSE.

  You can do what you want with this code, acknowledgment would be nice.

  http://www.devmobile.co.nz

*/
#include <RF24.h>
#include <sha204_library.h>
#include <TH02_dev.h>

// RF24 radio( ChipeEnable , ChipSelect )
RF24 radio(9, 10);
const byte FieldGatewayChannel = 15 ;
const byte FieldGatewayAddress[] = {"Base1"};
const rf24_datarate_e RadioDataRate = RF24_250KBPS;
const rf24_pa_dbm_e RadioPALevel = RF24_PA_HIGH;

// Payload configuration
const int PayloadSizeMaximum = 32 ;
char payload[PayloadSizeMaximum] = "";
const byte DeviceIdPlusCsvSensorReadings = 1 ;
const byte SensorReadingSeperator = ',' ;

// ATSHA204 secure authentication, validation with crypto and hashing (only using for unique serial number)
atsha204Class sha204(A3);
const int DeviceSerialNumberLength = 9 ;
uint8_t deviceSerialNumber[DeviceSerialNumberLength] = {""};
const int LoopSleepDelaySeconds = 10 ;

void setup()
{
  Serial.begin(9600);
  Serial.println("Setup called");

  // Retrieve the serial number then display it nicely
  sha204.getSerialNumber(deviceSerialNumber);

  Serial.print("SNo:");
  for (int i = 0; i < sizeof( deviceSerialNumber) ; i++)
  {
    // Add a leading zero
    if ( deviceSerialNumber[i] < 16)
    {
      Serial.print("0");
    }
    Serial.print(deviceSerialNumber[i], HEX);
    Serial.print(" ");
  }

  Serial.println();

  // Configure the Seeedstudio TH02 temperature & humidity sensor
  Serial.println("TH02 setup");
  TH02.begin();
  delay(100);

  // Configure the nRF24 module
  Serial.println("nRF24 setup");
  radio.begin();
  radio.setChannel(FieldGatewayChannel);
  radio.openWritingPipe(FieldGatewayAddress);
  radio.setDataRate(RadioDataRate) ;
  radio.setPALevel(RadioPALevel);
  radio.enableDynamicPayloads();

  Serial.println("Setup done");
}

void loop()
{
  int payloadLength = 0 ;
  float temperature ;
  float humidity ;

  Serial.println("Loop called");
  memset( payload, 0, sizeof( payload));

  // prepare the payload header with PayloadMessageType (top nibble) and DeviceID length (bottom nibble)
  payload[0] = (DeviceIdPlusCsvSensorReadings << 4) | sizeof(deviceSerialNumber) ;
  payloadLength += 1;

  // Copy the device serial number into the payload
  memcpy( &payload[payloadLength], deviceSerialNumber, sizeof( deviceSerialNumber));
  payloadLength += sizeof( deviceSerialNumber) ;

  // Read the temperature, humidity & battery voltage values then display nicely
  temperature = TH02.ReadTemperature();
  Serial.print("T:");
  Serial.print( temperature, 1 ) ;
  Serial.print( "C" ) ;

  humidity = TH02.ReadHumidity();
  Serial.print(" H:");
  Serial.print( humidity, 0 ) ;
  Serial.println( "%" ) ;

  // Copy the temperature into the payload
  payload[ payloadLength] = 't';
  payloadLength += 1 ;
  dtostrf(temperature, 6, 1, &payload[payloadLength]);
  payloadLength += 6;

  payload[ payloadLength] = ',';
  payloadLength += 1 ;

  // Copy the humidity into the payload
  payload[ payloadLength] = 'h';
  payloadLength += 1 ;
  dtostrf(humidity, 4, 0, &payload[payloadLength]);
  payloadLength += 4;

  // Powerup the nRF24 chipset then send the payload to base station
  Serial.print( "Payload length:");
  Serial.println( payloadLength );

  Serial.println( "nRF24 write" ) ;
  boolean result = radio.write(payload, payloadLength);
  if (result)
    Serial.println("Write Ok...");
  else
    Serial.println("Write failed.");

  Serial.println("Loop done");
  delay(LoopSleepDelaySeconds * 1000l);
}

Arduino monitor output

NanoArduinoNrf24

Prototype hardware

ArduinoNanonRF24

Bill of materials (prices as at Sep 2018)

  • Arduino Nano clone USD4.70
  • Easy Sensors Arduino Nano Radio Shield for nRF24L01 USD13
  • Seeedstudio Temperature and Humidity Sensor Pro USD11.50
  • Seeedstudio 4 pin Male Jumper to Grove 4 pin Conversion Cable USD2.90

Adafruit.IO temperature display when I moved the sensor outside.

NanoNrf24

Azure Meetup-Budget tank of 91 IoT

The premise of my Azure Meetup presentation was could you build an interesting project on a rainy weekend afternoon with a constrained budget (tank of 91 octane petrol) and minimal soldering .

Budget

Our family car is a VW Passat V6 4Motion which has a 62 Litre tank. The driver usually doesn’t usually stop to fill up until the fuel light has been on for a bit which helped.

PetrolReceipt

Based on the most recent receipt the budget was NZD132.

Where possible I purchased parts locally (the tech equivalent of food miles) or on special.

My bill of materials (prices as at 2018-06) was on budget.

The devDuino V2.2 and nRF24L01 module were USD26.20 approx. NZD37.50 (including freight) from elecrow.

Tradeoffs

I powered my Raspberry PI with a spare cellphone charger (make sure it can supply enough current to reliably power the device).

The devDuino V2.has an ATSHA204A which provides a guaranteed unique 72-bit serial number (makes it harder to screw up provisioning devices in the field).

I use a 32G MicroSD rather than a 16G MicroSD card as I have had issued with 16G cards getting corrupted by more recent upgrades (possibly running out of space?)

The Raspberry PI shield requires a simple modification to enable interrupt driven operation.

My sample devDuino V2.2 client uses an external temperature and humidity sensor, modifying this code to use the onboard temperature sensor an MCP9700 will be covered in another post.

The devDuino V2 is a little bit cheaper USD15.99 NZD37.31, has the same onboard temperature sensor as the V2.2 but no unique serial number chip.

The devDuino V4.0 has an onboard HTU21D temperature + humidity sensor but no unique serial number and the batteries are expensive.

The code and deployment instructions for the nRF24L01 field gateway applications for AdaFruit.IO and Azure IoT Hub/Azure IoT Central are available on hackster.IO.

RPiWithnRF24Plate

AdaFruit.IO has free and USD10.00/month options which work well for many hobbyist projects.

AdaFruitIO

Azure Meetup Christchurch notes

For the people who came to my Azure meetup session this evening

Sources of sensors and development boards

http://www.adafruit.com
http://www.elecrow.com (watering kits)
http://www.ingenuitymicro.com (NZ based dev boards)
http://www.netduino.com (.NetMF development boards)
http://www.makerfabs.com
http://www.seeedstudio.com
http://www.tindie.com

nRF24Shields for RPI devices
http://www.tindie.com/products/ceech/new-raspberry-pi-to-nrf24l01-shield/

nRF24Shields for *duino devices in AU
embeddedcoolness.com

Raspberry PI Source in CHC
http://www.wavetech.co.nz

RFM69 & LoRa Modules
http://www.wisen.com.au

local sensor and device resellers quick turnaround
http://www.mindkits.co.nz
http://www.nicegear.co.nz

http://www.diyelectricskateboard.com

The watch development platform
http://www.hexiwear.com

http://www.gowifi.co.nz (Antennas & other wireless kit based in Rangiora)

my projects
http://www.hackster.io/KiwiBryn
io.adafruit.com/BrynHLewis/dashboards/home-environment

Wireless field gateway Netduino client V2

This revised client is a Netduino V2Plus/V3 Ethernet/V3 Wifi device with a Silicon Labs SI7005 temperature & humidity sensor. These devices when used as sensor nodes can be battery powered and I use the Mac Address as the unique device identifier.

In this version of the protocol the message type & device identifier are nibbles packed into the first bye of the message. This saved a byte but limits the number of message types and device identifier length

//---------------------------------------------------------------------------------
// Copyright (c) 2018, devMobile Software
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//---------------------------------------------------------------------------------
using System;
using System.Net;
using System.Text;
using System.Threading;
using Microsoft.SPOT;
using Microsoft.SPOT.Hardware;
using Microsoft.SPOT.Net.NetworkInformation;
using devMobile.NetMF.Sensor;
using Gralin.NETMF.Nordic;
using SecretLabs.NETMF.Hardware.Netduino;

namespace devMobile.IoT.FIeldGateway.Netduino.Client
{
   class Client
   {
      private const byte nRF24Channel = 10;
      private const NRFDataRate nRF24DataRate = NRFDataRate.DR250kbps;
      private readonly byte[] nRF24ClientAddress = Encoding.UTF8.GetBytes("T&H01");
      private readonly byte[] nRF24BaseStationAddress = Encoding.UTF8.GetBytes("Base1");
      private static byte[] deviceIdentifier;
      private readonly OutputPort led = new OutputPort(Pins.ONBOARD_LED, false);
      private readonly NRF24L01Plus radio;
      private readonly SiliconLabsSI7005 sensor = new SiliconLabsSI7005();

      public Client()
      {
         radio = new NRF24L01Plus();
      }

      public void Run()
      {
         // Configure the nRF24 hardware
         radio.OnDataReceived += OnReceive;
         radio.OnTransmitFailed += OnSendFailure;
         radio.OnTransmitSuccess += OnSendSuccess;

         radio.Initialize(SPI.SPI_module.SPI1, Pins.GPIO_PIN_D7, Pins.GPIO_PIN_D3, Pins.GPIO_PIN_D2);
         radio.Configure(nRF24ClientAddress, nRF24Channel, nRF24DataRate);
         radio.Enable();

         // Setup the device unique identifer, in this case the hardware MacAddress
         deviceIdentifier = NetworkInterface.GetAllNetworkInterfaces()[0].PhysicalAddress;
         Debug.Print(" Device Identifier : " + BytesToHexString(deviceIdentifier));

         Timer humidityAndtemperatureUpdates = new Timer(HumidityAndTemperatureTimerProc, null, 15000, 15000);

         Thread.Sleep(Timeout.Infinite);
      }

          private void HumidityAndTemperatureTimerProc(object state)
      {
         led.Write(true);

         double humidity = sensor.Humidity();
         double temperature = sensor.Temperature();

         Debug.Print("H:" + humidity.ToString("F1") + " T:" + temperature.ToString("F1"));
         string values = "T " + temperature.ToString("F1") + ",H " + humidity.ToString("F0");

         // Stuff the single byte header ( payload type nibble & deviceIdentifierLength nibble ) + deviceIdentifier into first byte of payload
         byte[] payload = new byte[ 1 + deviceIdentifier.Length + values.Length];
         payload[0] =  (byte)((1 <> 4];

            // Mask off the upper 4 bits to get the rest of it.
            hexString += hexChars[bytes[b] & 0x0F];
         }

         return hexString;
      }
   }
}

Bill of materials (prices as at March 2018)