ESP32-Paxcounter

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

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

Currently supported IoT boards:

• Heltec LoRa-32
• TTGOv1
• TTGOv2
• Pycom LoPy
• Pycom LoPy4
• LoLin32 with LoraNode32 shield
• LoLin32 Lite with LoraNode32-Lite shield

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 and TTGOv2, for example.

Power consumption:

• Heltec ~650mW
• TTGOv1 ~650mW
• TTGOv2 ~670mW
• LoPy with expansion board: ~530mW
• LoPy pure, without expansion board: ~460mW
• LoLin32 with LoraNode32 shield: TBD
• LoLin32 Lite with LoraNode32-Lite shield: TBD

These results where metered with software version 1.2.0 during active wifi scan, no LoRa TX’ing, OLED display off, 5V USB powered.

Building

Use PlatformIO with your preferred IDE for development and building this code.

Before compiling the code, create file loraconf.h in the /src directory from the template loraconf.sample.h and populate it with your personal APPEUI und APPKEY for the LoRaWAN network. Only OTAA join is supported, not ABP. The DEVEUI 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 you enter a DEVEUI in loraconf.h it will be used instead.

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 board needs to be set manually. See these instructions how to do it.

For the LoPy/LoPy4 the original Pycom firmware is not needed here, so there is no need to update it before flashing Paxcounter. Just flash the paxcounter code on your LoPy/LoPy4. If you want to go back to the Pycom firmware, no problem. 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)

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.

Payload format description

FPort1:

byte 1:			16-bit Wifi counter, MSB
byte 2:			16-bit Wifi counter, LSB
byte 3:			16-bit BLE counter, MSB
byte 4:			16-bit BLE counter, LSB

FPort2:

see remote command set

Remote command set

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 Wifi scan RSSI limit

1 ... 255 used for wifi scan radius (greater values increase wifi scan radius, values 50...110 make sense)
0 = Wifi 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 screen saver mode

0 = screen saver off [default]
1 = screen saver on

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.

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 Wifi scan cycle and payload transmit cycle

0 ... 255 duration of a wifi scan cycle in seconds/2, after this payload is sent
e.g. 120 -> 1 cycle runs for 240 seconds [default]

0x0B set Wifi channel switch interval timer

0 ... 255 timeout for scanning 1 wifi channel in seconds/100
e.g. 50 -> each channel is scanned for 0,5 seconds [default]

0x0C set BLE scan cycle timer

0 ... 255 duration of a BLE scan cycle in seconds
e.g. 15 -> 1 cycle runs for 15 seconds [default]

0x0D set BLE scan cycle frequency

run BLE scan once after 0 ... 255 full wifi scans
e.g. 2 -> BLE scan runs once after each 2nd wifi scan [default]

0x0E set BLE scan mode

0 = disabled
1 = enabled [default]

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

0 = internal antenna [default]
1 = external antenna

0x10 set RGB led luminosity (works on LoPy/LoPy4 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 globals.h with the following definition:

byte 1:			Lora SF (7..12)
byte 2:			Lora TXpower (2..15)
byte 3:			Lora ADR (1=on, 0=off)
byte 4:			Screensaver status (1=on, 0=off)
byte 5:			Display status (1=on, 0=off)
byte 6:			Counter mode (0=cyclic unconfirmed, 1=cumulative, 2=cyclic confirmed)
bytes 7-8:		RSSI limiter threshold value (negative)
byte 9:			Wifi scan cycle duration in seconds/2 (0..255)
byte 10:		Wifi channel switch interval in seconds/100 (0..255)
byte 11:		BLE scan cycle duration in seconds (0..255)
byte 12:		BLE scan frequency, do once after (0..255) full wifi scans
byte 13:		BLE scan mode (1=on, 0=0ff)
byte 14:		Wifi antenna switch (0=internal, 1=external)
byte 15:		RGB LED luminosity (0..100 %)
bytes 16-25:		Software version (ASCII format)

0x81 get device uptime

bytes 1-7:		Uptime in seconds (little endian format)

0x82 get device cpu temperature

bytes 1-3:		chip temperature in celsius (little endian format)

RGB Led color description

Description of the RGB LED color (Lopy and Lolin32 only):

• Yellow quick blink
  • LoRaWAN join
• Blue blink
  • LoRaWAN transmit (including receive windows)
• Magenta each blink
  • BLE Scan, seen a device (new or not)

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 Charles Hallard (https://github.com/hallard) for major contributions to this project.