ESP32-Paxcounter

Wifi & Bluetooth driven, LoRaWAN enabled, battery powered mini Paxcounter built on cheap ESP32 LoRa IoT boards

--> see development branch of this repository for latest alpha version <--

Use case

Paxcounter is a proof-of-concept device for metering passenger flows in realtime. It counts how many mobile devices are around. This gives an estimation how many people are around. Paxcounter detects Wifi and Bluetooth signals in the air, focusing on mobile devices by filtering vendor OUIs in the MAC adress.

Intention of this project is to do this without intrusion in privacy: You don't need to track people owned devices, if you just want to count them. Therefore, Paxcounter does not persistenly store MAC adresses and does no kind of fingerprinting the scanned devices.

Bonus of this project is that metered data is transferred via a LoRaWAN network, not via usual GSM/LTE or Wifi uplink.

You can build this project battery powered and reach a full day uptime with a single 18650 Li-Ion cell.

This can all be done with a single small and cheap ESP32 board for less than $20.

Hardware

Supported ESP32 based LoRa IoT boards:

• Heltec LoRa-32
• TTGOv1
• TTGOv2
• TTGOv2.1
• TTGO T-Beam
• Pycom LoPy
• Pycom LoPy4
• Pycom FiPy
• LoLin32 + LoraNode32 shield
• LoLin32 Lite + LoraNode32-Lite shield

Depending on board hardware following features are supported:

• LED
• OLED Display
• RGB LED
• button
• silicon unique ID
• battery voltage monitoring
• GPS

Target platform must be selected in platformio.ini.
Hardware dependent settings (pinout etc.) are stored in board files in /hal directory.

3D printable cases can be found (and, if wanted so, ordered) on Thingiverse, see Heltec, TTGOv2, TTGOv2.1 for example.

Power consumption was metered at around 1000mW, depending on board (i.e. has display or not) and user settings in paxcounter.conf. If you are limited on battery, you may want to save around 30% power by disabling bluetooth (commenting out line #define BLECOUNTER in paxcounter.conf).

Preparing

Before compiling the code,

• edit paxcounter.conf and taylor settings in this file according to your needs and use case. Please take care of the duty cycle regulations of the LoRaWAN network you're going to use.

• create file loraconf.h in your local /src directory using the template loraconf.sample.h and populate it with your personal APPEUI und APPKEY for the LoRaWAN network. If you're using popular TheThingsNetwork you can copy&paste the keys from TTN console or output of ttnctl.

To join the network only method OTAA is supported, not ABP. The DEVEUI for OTAA will be derived from the device's MAC adress during device startup and is shown as well on the device's display (if it has one) as on the serial console for copying it to your LoRaWAN network server settings.

If your device has a fixed DEVEUI enter this in your local loraconf.h file. During compile time this DEVEUI will be grabbed from loraconf.h and inserted in the code.

If your device has silicon Unique ID which is stored in serial EEPROM Microchip 24AA02E64 you don't need to change anything. The Unique ID will be read during startup and DEVEUI will be generated from it, overriding settings in loraconf.h.

Building

Use PlatformIO with your preferred IDE for development and building this code. Make sure you have latest PlatformIO version.

Uploading

To upload the code to your ESP32 board this needs to be switched from run to bootloader mode. Boards with USB bridge like Heltec and TTGO usually have an onboard logic which allows soft switching by the upload tool. In PlatformIO this happenes automatically.

The LoPy/LoPy4/FiPy board needs to be set manually. See these instructions how to do it. Don't forget to press on board reset button after switching between run and bootloader mode.

The original Pycom firmware is not needed, so there is no need to update it before flashing Paxcounter. Just flash the compiled paxcounter binary (.elf file) on your LoPy/LoPy4/FiPy. If you later want to go back to the Pycom firmware, download the firmware from Pycom and flash it over.

Legal note

Depending on your country's laws it may be illegal to sniff wireless networks for MAC addresses. Please check and respect your country's laws before using this code!

(e.g. US citizens may want to check Section 18 U.S. Code § 2511 and discussion on this)

(e.g. UK citizens may want to check Data Protection Act 1998 and GDPR 2018)

(e.g. Citizens in the the Netherlands may want to read this article and this article)

Note: If you use this software you do this at your own risk. That means that you alone - not the authors of this software - are responsible for the legal compliance of an application using this or build from this software and/or usage of a device created using this software. You should take special care and get prior legal advice if you plan metering passengers in public areas and/or publish data drawn from doing so.

Privacy disclosure

Paxcounter generates identifiers for sniffed MAC adresses and collects them temporary in the device's RAM for a configurable scan cycle time (default 240 seconds). After each scan cycle the collected identifiers are cleared. Identifiers are generated by salting and hashing MAC adresses. The random salt value changes after each scan cycle. Identifiers and MAC adresses are never transferred to the LoRaWAN network. No persistent storing of MAC adresses, identifiers or timestamps and no other kind of analytics than counting are implemented in this code. Wireless networks are not touched by this code, but MAC adresses from wireless devices as well within as not within wireless networks, regardless if encrypted or unencrypted, are sniffed and processed by this code. If the bluetooth option in the code is enabled, bluetooth MACs are scanned and processed by the included BLE stack, then hashed and counted by this code.

LED blink pattern

Mono color LED:

• Single Flash (50ms): seen a new Wifi or BLE device
• Quick blink (20ms on each 1/5 second): joining LoRaWAN network in progress or pending
• Small blink (10ms on each 1/2 second): LoRaWAN data transmit in progress or pending
• Long blink (200ms on each 2 seconds): LoRaWAN stack error

RGB LED:

• Green each blink: seen a new Wifi device
• Magenta each blink: seen a new BLE device
• Yellow quick blink: joining LoRaWAN network in progress or pending
• Blue blink: LoRaWAN data transmit in progress or pending
• Red long blink: LoRaWAN stack error

Payload format

You can select different payload formats in paxcounter.conf:

• Plain uses big endian format and generates json fields, e.g. useful for TTN console

• Packed uses little endian format and generates json fields

• CayenneLPP generates MyDevices Cayenne readable fields

If you're using TheThingsNetwork (TTN) you may want to use a payload converter. Go to TTN Console - Application - Payload Formats and paste the code example below in tabs Decoder and Converter. This way your MQTT application can parse the fields pax, ble and wifi.

To track a paxcounter device with on board GPS and at the same time contribute to TTN coverage mapping, you simply activate the TTNmapper integration in TTN Console. The formats plain and packed generate the fields latitude, longitude and hdop required by ttnmapper.

Hereafter described is the default plain format.

LoRaWAN Port #1:

Paxcounter data

byte 1-2:	Number of unique pax, first seen on Wifi
byte 3-4:	Number of unique pax, first seen on Bluetooth [0 if BT disabled]

GPS data (only, if GPS is present and has a fix)

bytes 5-8:	GPS latitude
bytes 9-12:	GPS longitude
bytes 13-14:	GPS number of satellites
bytes 15-16:	GPS HDOP
bytes 17-18:	GPS altitude [meter]

LoRaWAN Port #2:

- see remote control -

plain_decoder.js

function Decoder(bytes, port) {
  var decoded = {};

  if (port === 1) {
    var i = 0;
    decoded.wifi = (bytes[i++] << 8) | bytes[i++];
    decoded.ble =  (bytes[i++] << 8) | bytes[i++];
    if (bytes.length > 4) {
      decoded.latitude =  ( (bytes[i++] << 24) | (bytes[i++] << 16) | (bytes[i++] << 8) | bytes[i++] );
      decoded.longitude = ( (bytes[i++] << 24) | (bytes[i++] << 16) | (bytes[i++] << 8) | bytes[i++] );
      decoded.sats = 	  (  bytes[i++] );
      decoded.hdop = 	  (  bytes[i++] << 8)  | (bytes[i++] );
      decoded.altitude =  (  bytes[i++] << 8)  | (bytes[i++] );
    }
  }

  return decoded;
}

plain_converter.js

function Converter(decoded, port) {
  
  var converted = decoded;

  if (port === 1) {
    converted.pax = converted.ble + converted.wifi;
    if (converted.hdop) {
      converted.hdop /= 100;
      converted.latitude /= 1000000;
      converted.longitude /= 1000000;
    }
  }

  return converted;
}

Remote control

The device listenes for remote control commands on LoRaWAN Port 2. Each command is followed by exactly one parameter. Multiple command/parameter pairs can be concatenated and sent in one single payload downlink.

Note: all settings are stored in NVRAM and will be reloaded when device starts. To reset device to factory settings press button (if device has one), or send remote command 09 02 09 00 unconfirmed(!) once.

0x01 set scan RSSI limit

1 ... 255 used for wifi and bluetooth scan radius (greater values increase scan radius, values 50...110 make sense)
0 = RSSI limiter disabled [default]

0x02 set counter mode

0 = cyclic unconfirmed, mac counter reset after each wifi scan cycle, data is sent only once [default]
1 = cumulative counter, mac counter is never reset
2 = cyclic confirmed, like 0 but data is resent until confirmation by network received

0x03 set GPS data on/off

0 = GPS data off
1 = GPS data on, appends GPS data to payload, if GPS is present and has a fix [default]

0x04 set display on/off

0 = display off
1 = display on [default]

0x05 set LoRa spread factor

7 ... 12 [default: 9]

0x06 set LoRa TXpower

2 ... 15 [default: 15]

0x07 set LoRa Adaptive Data Rate mode

0 = ADR off
1 = ADR on [default]

Note: set ADR to off, if device is moving, set to on, if not.
If ADR is set to on, SF value is shown inverted on display.

0x08 do nothing

useful to clear pending commands from LoRaWAN server quere, or to check RSSI on device

0x09 reset functions

0 = restart device
1 = reset MAC counter to zero
2 = reset device to factory settings

0x0A set LoRaWAN payload send cycle

0 ... 255 payload send cycle in seconds/2
e.g. 120 -> payload is transmitted each 240 seconds [default]

0x0B set Wifi channel switch interval timer

0 ... 255 duration for scanning a wifi channel in seconds/100
e.g. 50 -> each channel is scanned for 500 milliseconds [default]

0x0C set Bluetooth channel switch interval timer

0 ... 255 duration for scanning a bluetooth advertising channel in seconds/100
e.g. 8 -> each channel is scanned for 80 milliseconds [default]

0x0D (NOT YET IMPLEMENTED) set BLE and WIFI vendorfilter mode

0 = disabled (use to count devices, not people)
1 = enabled [default]

0x0E set Bluetooth scanner

0 = disabled
1 = enabled [default]

0x0F set WIFI antenna switch (works on LoPy/LoPy4/FiPy only)

0 = internal antenna [default]
1 = external antenna

0x10 set RGB led luminosity (works on LoPy/LoPy4/FiPy and LoRaNode32 shield only)

0 ... 100 percentage of luminosity (100% = full light)
e.g. 50 -> 50% of luminosity [default]

0x80 get device configuration

device answers with it's current configuration. The configuration is a C structure declared in file main.h with the following definition:

byte 1:			Lora SF (7..12) [default 9]
byte 2:			Lora TXpower (2..15) [default 15]
byte 3:			Lora ADR (1=on, 0=off) [default 1]
byte 4:			Screensaver status (1=on, 0=off) [default 0]
byte 5:			Display status (1=on, 0=off) [default 0]
byte 6:			Counter mode (0=cyclic unconfirmed, 1=cumulative, 2=cyclic confirmed) [default 0]
bytes 7-8:		RSSI limiter threshold value (negative) [default 0]
byte 9:			Lora Payload send cycle in seconds/2 (0..255) [default 120]
byte 10:		Wifi channel switch interval in seconds/100 (0..255) [default 50]
byte 11:		Bluetooth channel switch interval in seconds/100 (0..255) [efault 10]
byte 12:		Bluetooth scanner status (1=on, 0=0ff) [default 1]
byte 13:		Wifi antenna switch (0=internal, 1=external) [default 0]
byte 14:		Vendorfilter mode (0=disabled, 1=enabled) [default 0]
byte 15:		RGB LED luminosity (0..100 %) [default 30]
byte 16:		GPS send data mode (1=on, 0=ff) [default 1]
bytes 17-27:		Software version (ASCII format, terminating with zero)

0x81 get device status

bytes 1-2:		Battery voltage in millivolt, 0 if unreadable
bytes 3-10:		Uptime in seconds
bytes 11-14:		Chip temperature in degrees celsius

0x84 get device GPS status

bytes 1-4:		Latitude
bytes 5-8:		Longitude
byte 9:			Number of satellites
byte 10-11:		HDOP
bytes 12-13:		altidute [meter]

License

Copyright 2018 Oliver Brandmueller ob@sysadm.in

Copyright 2018 Klaus Wilting verkehrsrot@arcor.de

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.

NOTICE: Parts of the source files in this repository are made available under different licenses, see file LICENSE.txt in this repository. Refer to each individual source file for more details.

Credits

Thanks to

• Oliver Brandmüller for idea and initial setup of this project
• Charles Hallard for major code contributions to this project
• robbi5 for the payload converter