Node Specifications

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The electronics of the City of Things experiment nodes

There is currently only a single type of node available in the City of Things testbed. It consists of of an apu2c4 embedded pc with two WiFi interfaces and a number of additional radio modules that are connected through USB. Depending on the specific node, it supports the following technologies out of the box:

  • WiFi 802.11ac on 2.4 GHz and 5GHz (ath10k and/or intel wifi)
  • WiFi 802.11n on 2.4 GHz and 5GHz (ath9k)
  • Bluetooth 4.0 with full BLE Support
  • IEEE 802.15.4 on 2.4 GHz and IEEE 802.15.4g 868MHz
  • Dash7 on 433MHz and 868MHz
  • LoRaWAN on 868MHz (client only)

An overview of which nodes are equipped with what hardware can be found here.

Node Hardware

Each node uses a PCEngines apu2c4 board as a central controller. This board is equipped with the following hardware:

  • CPU: AMD GX-412TC 1GHz Quad-core CPU (onboard)
  • Memory: 4GB DDR3-1333 MHz (onboard)
  • Storage: 240GB Samsung EVO 850 SSD (mSATA)

The apu2c4 is also equipped with two of the following WiFi cards. See this page for a list of which hardware is present in each node.

Compex WLE900VX
  • Atheros (ath10k) QCA9880 Chipset
  • Supports IEEE 802.11 a/b/g/n/ac
  • Operates on both 2.4GHz and 5GHz
  • Connected to three dual-band antennas (3x3 MIMO is supported).
  • Known as interface wlp1s0 in linux
Compex WLE200NX
  • Atheros (ath9k) AR9280 Chipset
  • Supports IEEE 802.11 a/b/g/n
  • Operates on both 2.4GHz and 5GHz
  • Connected to two dual-band antennas (2x2 MIMO is supported).
  • Known as interface wlp5s0 in linux
Intel 7260 WiFi-AC + Bluetooth
  • Intel 7260 Chipset
  • Supports WiFi a/b/g/n/ac and Bluetooth 4.0
  • Operates on both 2.4GHz and 5GHz (client mode only)
  • Connected to two dual-band antennas (2x2 MIMO is supported).
  • Known as interface wlp5s0 in linux

Connected USB Devices

Each experiment node is equipped with a number of embedded wireless devices connected trough USB. These devices usually consist of a microcontroller with either an embedded or an add-on wireless radio. Each device is equipped with a JTAG/SWD-debugger for programming the device. If the device does not have an on-board debugger a standalone JTAG/SWD-debugger is provided for the device. Likewise each device is also equipped with a USB-to-serial converter to allow the device to communicate with the host. As with the JTAG-debugger the device is connected to a standalone USB-to-serial converter if it does not have one onboard.

OpenUSB (IEEE 802.15.4)

The OpenUSB board used in the experiment nodes

The OpenUSB mote consists of an OpenMote-CC2538 connected to an OpenUSB base board. It has the following features:

  • MCU: TI CC2538 SoC (32K ram, 512K flash)
  • 2.4 GHz radio: IEEE 802.15.4 tranceiver embedded in the MCU
  • 868 MHz radio: TI CC1200 general purpose tranceiver (compatible with IEEE 802.15.4g)

Serial & JTAG Interface:

Please note that the JTAG debugger is (1) only supported in windows, (2) not required to flash/erase the OpenUSB mote and (3) only present to allow the system administrators to recover bricked OpenUSB motes. Flashing / Erasing the OpenUSB mote is done through the serial port. See the OpenUSB Tutorial for more information.

EZR USB (Dash 7)

The 433Mhz EZR USB board used in the experiment nodes
The 868Mhz EZR USB board used in the experiment nodes

The experiment node contains two EZRUSB boards. These boards are identical except that one is equipped with a 433MHz radio front-end and the other one is equipped with an 868MHz radio front-end. These boards have the following features:

  • MCU: Silabs Leopard Gecko EZR32LG330F60G SoC (32K ram, 256K flash)
  • Radio: general purpose, Dash7 compatible, 433MHz/868Mhz tranceiver embedded in the MCU

Serial & JTAG Interface:

Please note that, for security reasons, the USB-port of the EZR USB is not connected to the host. Communication with the EZR USB module is only possible over the serial interface.

EFM32GG+RFM95W (LoRa)

The Lora module used in the experiment nodes

LoRa(WAN) connectivity is provided through a EFM Giant Gecko development board connected to an RFM95W LoRa tranceiver.

Serial & JTAG Interface:


Antennas

The antennas of the City of Things experiment nodes

Each experiment node is equiped with a number of different antennas (10 in total). These antennas are housed in a separate plastic enclosure to ensure that the placement of the antennas is consistent. Each radio interface is connected to one or more antennas using low loss coax cable. Depending on the operating frequency of the radio interface, a different type of antenna is used.