This repository contains a description of the NanoSEC switch matrix, as well as all the relevant source code, to control the board. The material in this repository corresponds to the paper:

F. Frank et al., "A Dedicated Mixed-Signal Characterisation and Testing Framework for Novel Digital Security Circuits That Use Carbon-Nanotube-Based Physical Unclonable Functions," 2022 11th International Conference on Modern Circuits and Systems Technologies (MOCAST), 2022, pp. 1-4, doi: 10.1109/MOCAST54814.2022.9837567

The circuit is subdivided into two parts, a control part and a measurement part. The measurement part consists of a 12 V power supply forwarded to four darlington arrays (ULN2003APW), which are responsible for switching the Finder 40.41 relays. Single lines on the darlington arrays are controlled by two 2/16 ADG726 multiplexers. The multiplexer transform a four bit input address signal to a parallel output signal which selects a specific row and column relay over the Darlington arrays. The multiplexers are controlled by a Arduino Nano.

The measurement part consists of four BNC connectors I_D, V_DS, V_GS and GND. V_DS connects is forwarded to each CNT_FETs on the matrix not switched. I_D is forwarded to the selected row. GND is forwarded to the selected column. V_GS is connected to the global gate.

This table contains an overview of the components on the Motherboard. Each component is identified by a Symbol ID.

The following tables contain the connections between the components described in 1.1.

Routed on the Backside. Common length of 316 mm.

Routed on the Backside. Common length of 140 mm.

Connect the Arduino Nano to the NanoSEC Switch Matrix like shown in the following picture. Use a Micro USB cable to connect the arduino to the computer. The Arduino is working if the green 'ON' led is green. If the Arduino was flashed once the firmware is automatically restarted on the device when it's connected to the power supply of the computer. The Arduino should show up in the device manager. On linux the device should be registered as '/dev/ttyUSB0'.

A DC power supply must be connected to drive the relays. The power supply can be connected by the barrel jack connector on the left buttom of the board or by connecting jumper cables to the power supply pins below the barrel jack connector.

Please check the maximum ratings like described in the following table.

When two relays are switched a current of 83mA can be observed on a DC power supply like shown in the subsequent figure.

The board contains several Jumpers for debugging purposes or to execute differnt types of measurements.

TODO add jumper descriptions.

The code is basically subdivided into two different components.

• The Arduino Firmware which is the code executed on the Arduino Nano. It accepts commands via an UART interface and forwards the commands to the multiplexers, which switch the corresponding rows and columns.
  
  
• The Client Side API is executed on the computer responsible for the test execution and communicates the commands to the Arduino Nano via an UART interface.

On Windows:

Follow the link:
https://git-scm.com/download/win
And install the executable.

On Linux:

# apt-get install git

$ git clone https://github.com/FlorianFrank/measurement_switch_matrix.git
Cloning into 'measurement_switch_matrix'...
Username for 'https://github.com': test
Password for 'https://[email protected]': test123

 $ git pull

Updates the current working copy to the current version on the repo.

First hte avr-gcc compiler must be installed. Therefore, go to Arduino_Firmware/Toolchain/SysGCC and execute avr-gcc5.3.0.exe . You see an installation dialog. Like shown the in the figure below. Select the Arduino_firmware/Toolchain/ directory and install the compiler.

Further tools like cmake and ninja are already included in the repository in the Toolchain folder and do not have to be installed manually.

We are using AVRDude to flash the firmware image on the Arduino Nano. You can find the installation under Toolchain/AVRDude.

On Windows:
There is alredy a precompiled version under AVRDude/bin/Win32 so the files don't need to be compiled

On Linux:
Go to AVRDude and run:

./compile_linux.sh

Afterwareds you will find the avr compilation under bin/amd64.

Press the windows button on the keyboard and go to the device manager. The device should be listed as "USB Serial Port (COM[ID])". In a next step adjust the settings.cmake.

In the Arduino_Firmware folder you can find a settings.cmake file.
These contain the most important properties of the firmware. To build and flash the Arduino firmware. Only the USB_Port must be adjusted. You can check out the correct 'COM' port in the device manager.

option(BUILD_DOCUMENTATION "BUILD_DOCUMENTATION" OFF)
option(ARDUINO_NANO_OLD "BUILD for old Arduino Nano Board (blue)" ON)
option(USB_PORT "Set the USB port on Linux /dev/ttyUSB0 on windows COM<comID>" "COM6")
option(ARDUINO_PROGRAMMER "Set the programmer to be used to flash the Arduino Nano" "avrispmkii")
option(ETHERNET_SUPPORT "Enable Ethernet utilizing using the AZ delivery ENC28J60 Ethernet Shield. Disable UART" ON)

When using the old version of the Arduino Nano (blue PCB) the flag ARDUINO_NANO_OLD must be set to ON.

option(ARDUINO_NANO_OLD "BUILD for old Arduino Nano Board (blue)" OFF)
# uses the atmega328 programmer

option(ARDUINO_NANO_OLD "BUILD for old Arduino Nano Board (blue)" ON)
# uses the atmega328old programmer

When using the old version of the Arduino Nano (blue PCB) the flag ARDUINO_NANO_OLD must be set to ON. To compile the firmware for the new version (green PCB) this flag must be disabled. Set the BUILD_DOCUMENTATION option to automatically build the Code Documentation as HTML and Latex files.

On Linux run:

cd ./Arduino_Firmware
./compile.sh

On Windows run:

cd ./Arduino_Firmware
./compile.bat

After comiling you find a folder ./build in the Arduino Firmware directory containing the firmware to be flashed on the Arduino Nano. The firmware is build sucessfully when you see an output similar to the command line output below:

[100%] Linking CXX executable nanosec_crossbar_controller.elf
Generating EEP image
Generating HEX image
Calculating image size
Firmware Size:  [Program: 8186 bytes (25.0%)]  [Data: 641 bytes (31.3%)] on atmega328p
EEPROM   Size:  [Program: 0 bytes (0.0%)]  [Data: 0 bytes (0.0%)] on atmega328p

[100%] Built target nanosec_crossbar_controller

On Linux run after compiling:

cd ./Arduino_Firmware
./flash.sh

On Windows after compiling:

cd ./Arduino_Firmware
./flash.bat

fterwards you should see following output:

avrdude: Version 6.4
         Copyright (c) Brian Dean, http://www.bdmicro.com/
         Copyright (c) Joerg Wunsch

         System wide configuration file is "/home/florianfrank/Documents/Research/Projects/NanoSec/measurement_switch_matrix/Arduino_Firmware/Toolchain/AVRDude/config/avrdude.conf"
         User configuration file is "/home/florianfrank/.avrduderc"
         User configuration file does not exist or is not a regular file, skipping

         Using Port                    : /dev/ttyUSB0
         Using Programmer              : arduino
         Overriding Baud Rate          : 115200
         AVR Part                      : ATmega328P
         Chip Erase delay              : 9000 us
         PAGEL                         : PD7
         BS2                           : PC2
         RESET disposition             : dedicated
         RETRY pulse                   : SCK
         serial program mode           : yes
         parallel program mode         : yes
         Timeout                       : 200
         StabDelay                     : 100
         CmdexeDelay                   : 25
         SyncLoops                     : 32
         ByteDelay                     : 0
         PollIndex                     : 3
         PollValue                     : 0x53
         Memory Detail                 :

                                  Block Poll               Page                       Polled
           Memory Type Mode Delay Size  Indx Paged  Size   Size #Pages MinW  MaxW   ReadBack
           ----------- ---- ----- ----- ---- ------ ------ ---- ------ ----- ----- ---------
           eeprom        65    20     4    0 no       1024    4      0  3600  3600 0xff 0xff
           flash         65     6   128    0 yes     32768  128    256  4500  4500 0xff 0xff
           lfuse          0     0     0    0 no          1    1      0  4500  4500 0x00 0x00
           hfuse          0     0     0    0 no          1    1      0  4500  4500 0x00 0x00
           efuse          0     0     0    0 no          1    1      0  4500  4500 0x00 0x00
           lock           0     0     0    0 no          1    1      0  4500  4500 0x00 0x00
           calibration    0     0     0    0 no          1    1      0     0     0 0x00 0x00
           signature      0     0     0    0 no          3    1      0     0     0 0x00 0x00

         Programmer Type : Arduino
         Description     : Arduino
         Hardware Version: 3
         Firmware Version: 4.4
         Vtarget         : 0.3 V
         Varef           : 0.3 V
         Oscillator      : 28.800 kHz
         SCK period      : 3.3 us

avrdude: AVR device initialized and ready to accept instructions

Reading | ################################################## | 100% 0.01s

avrdude: Device signature = 0x1e950f (probably m328p)
avrdude: safemode: lfuse reads as 0
avrdude: safemode: hfuse reads as 0
avrdude: safemode: efuse reads as 0
avrdude: reading input file "/home/florianfrank/Documents/Research/Projects/NanoSec/measurement_switch_matrix/Arduino_Firmware/build/nanosec_crossbar_controller.hex"
avrdude: writing flash (8186 bytes):

Writing | ################################################## | 100% 3.07s

avrdude: 8186 bytes of flash written
avrdude: verifying flash memory against /home/florianfrank/Documents/Research/Projects/NanoSec/measurement_switch_matrix/Arduino_Firmware/build/nanosec_crossbar_controller.hex:
avrdude: load data flash data from input file /home/florianfrank/Documents/Research/Projects/NanoSec/measurement_switch_matrix/Arduino_Firmware/build/nanosec_crossbar_controller.hex:
avrdude: input file /home/florianfrank/Documents/Research/Projects/NanoSec/measurement_switch_matrix/Arduino_Firmware/build/nanosec_crossbar_controller.hex contains 8186 bytes
avrdude: reading on-chip flash data:

Reading | ################################################## | 100% 2.75s

avrdude: verifying ...
avrdude: 8186 bytes of flash verified
avrdude: reading input file "/home/florianfrank/Documents/Research/Projects/NanoSec/measurement_switch_matrix/Arduino_Firmware/build/nanosec_crossbar_controller.eep"
avrdude: writing eeprom (0 bytes):

Writing | ################################################## | 100% 0.00s

avrdude: 0 bytes of eeprom written
avrdude: verifying eeprom memory against /home/florianfrank/Documents/Research/Projects/NanoSec/measurement_switch_matrix/Arduino_Firmware/build/nanosec_crossbar_controller.eep:
avrdude: load data eeprom data from input file /home/florianfrank/Documents/Research/Projects/NanoSec/measurement_switch_matrix/Arduino_Firmware/build/nanosec_crossbar_controller.eep:
avrdude: input file /home/florianfrank/Documents/Research/Projects/NanoSec/measurement_switch_matrix/Arduino_Firmware/build/nanosec_crossbar_controller.eep contains 0 bytes
avrdude: reading on-chip eeprom data:

Reading | ################################################## | 100% 0.00s

avrdude: verifying ...
avrdude: 0 bytes of eeprom verified

avrdude: safemode: lfuse reads as 0
avrdude: safemode: hfuse reads as 0
avrdude: safemode: efuse reads as 0
avrdude: safemode: Fuses OK (E:00, H:00, L:00)

avrdude done.  Thank you.

A lightweight communication protocol is implemented on the Arduino Nano tunneled over the USB UART interface. A UART connection is established by simply plugin in the Mini USB cable. On linux for example, the device is typically available under "/dev/ttyUSB0" on Windows the device can be seen in the device manager under "COMxx".

Sample accessing the protocol on linux:

$ serial /dev/ttyUSB0
$ connect
-> ack
$ r: 1
 ack
$ c: 1
 ack

$ column: 15
 error: Invalid index

$ disconnect
 ack

In the folder python_tester you can find a python test application, which switches all relays in an infinite loop.

• On Windows:

  • Install Python3 (e.g. 3.10.2) from the official home page.
  • Install pyserial from the official home page

• On Linux

  # Install python3
  $ sudo apt-get install python3
  $ sudo apt-get install pip3
  $ sudo pip install pyserial

To run the program execute following command. Thereby <serial_port> must be replaced with the actual port to which the Arduino is connected. On Linux this is typically /dev/ttyUSB0 on Windows computers you can look up the port in the device manager.

$ python3 switch_matrix_tester.py "<serial_port>"

The switch matrix includes TCP communication capabilities, leveraging the ENC28J60 Ethernet Shield. Ethernet support can be activated using the following command within the settings.cmake file:

option(ETHERNET_SUPPORT "Enable Ethernet utilizing using the AZ delivery ENC28J60 Ethernet Shield. Disable UART" ON)

in the settings.cmake file.

This configuration will deactivate the UART interface and enable the Ethernet shield for communication.

The default ethernet configuration is defined in the file /Include/ethernet/EthernetDefines.h.

/**
 * @brief This file contains all definition required to execute the Ethernet Controller.
 */
#define MAC_ADDRESS 0x00,0x10,0xFA,0x6E,0x38,0x4A
#define IP_SIZE 4
#define DEFAULT_IP 192,168,0,2
#define DEFAULT_PORT 2000
#define ETHERNET_LOOP_DELAY_MS 1

#define ETH_MAX_MSG_SIZE 64
#define ETH_MAX_RESPONSE_SIZE 64

The Ethernet interface supports multiple commands that must be transmitted to the endpoint 192.168.0.2:2000 in the default configuration. The following commands are supported:

The following commands are supported.

Request: {"cmd": "*IDN?"}
Response:  {"status":"ok","idn":"NANOSec Crossbar Controller"}

This command is used to identify the switch matrix. The identification string can be customized within the EthernetCommandParser implementation.

It additionally supports setting only the row selector:

Request: {"cmd": "SET_ROW", "row": "10"}
Response: b'{"status":"ok","row":"10"}'

If the command was successful it returns a status: ok and the set row.

Simultanously the column can be set:

Request: {"cmd": "SET_COLUMN", "column": "10"}
Response: b'{"status":"ok","column":"2"}'

Furthermore it also supports a JSON command setting both the row and column at the same time:

Request: {"cmd": "SET_ROW_COLUMN", "row": "1", "column": "2"}
Response: b'{"status":"ok","row":1,"column":2}'

In case of any error an error string is returned, e.g.

Request: {"cmd": "INVALID_COMMAND", "row": "1", "column": "2"}
Response: {"status":"err","msg":"Could not parse cmd INVALID_COMMAND"}'

A Python testing script is available under python_tester/ethernet_tester for verifying the functionality of the switch matrix's different commands. You can execute the script using the following command:

$ python3 ethernet_tester

**********************
Run NANOSec Switch Matrix TCP tester
**********************


Send: {"cmd": "*IDN?"}
Received: b'{"status":"ok","idn":"NANOSec Crossbar Controller"}'
Send: {"cmd": "SET_ROW", "row": "4"}
Received: b'{"status":"ok","row":"4"}'
Send: {"cmd": "SET_COLUMN", "column": "10"}
Received: b'{"status":"ok","column":"10"}'
Send: {"cmd": "SET_ROW_COLUMN", "row": "1", "column": "2"}
Received: b'{"status":"ok","row":1,"column":2}'


Execution finished! Exit program!