This project is the third variation of the theme "creation of RNG generators based on nuclear decay", you can find the other two implementations here:
NuclearRNG Version 1
NuclearRNG Version 2
This version, differently from the previous two, does not use a Geiger–Müller tube nor a classic Geiger counter but an array of PIN diodes produced by Teviso company, named BG51:
Using that component, the implementation of the present appliance is greatly simplified, avoiding all the high voltage circuitry necessary to operate a Geiger tube. Furthermore, the small dimensions of the component permits to implement a very compact device.
- A Raspberry Pico (RP2040) is employed as microcontroller platform;
- A BG51 radiation sensor;
- Some circuitry to filter the power source and to convert the logic level of the sensor output.
-
As radiation source, a piece of ceramic coated with uranium oxide is employed. It comes from a salt / pepper dispenser I purchased set from the 50s, unfortunately one was damaged, the handle was broken and that peace is now temporarily the source of this appliance:
-
A lead metallic shield contains both a radiation source and the sensor, fixed with non-permanent glue. The shielding has two functions, prevent radiation to reach the external environment and prevent external interferences, both particles (particle injection attack ? :-) ) and electromagnetic. In fact the product, as stated in datasheets, requires some kind of shielding:
-
A circuit to stabilize input voltage is required, I tested also with boards different from Pico having the same results: being the sensor sensible to rumor in the power supply, a filter is mandatory. Testing without filtering in power input, produced distortions in the output. I implemented a filter using the specifications in Teviso's manuals and all problems disappeared.
-
Datasheet tell us that at least 4V are required, so I opted for 5V and a small logic level converter to interface the sensor to Pico's 3V logic. This operation could be made with many different solution, I used my own.
- In loop, a register with a representation od an unsigned integer is cyclically increased from 0 to its maximum value, when it reaches the maximum it restarts from zero. When a particle is detected, the current value is stored in queue ready to be deployed on request;
- Default queue length is 10240 bytes.
- When a socket connects to the appliance via WIFI, a message with the following format is given as response:
ready\n
where '\n' is "newline" character
- You require a RN sending the message:
req
- Then you'll receive a RN in an answer with the following format:
<random_number><separator><generator_number><separator><available_numbers><newline>
where:
- the first field is a random number in the range 0-15 or the number 16 if an error was generated or no number is available yet;
- the second field represent the original value of the register incremented in loop to extract the random number using module operator of integer division by the specific range (0-255, 8-bit integers), it's provided as safeguard to verify that the loop cover every possible value for a given event frequency;
- the separator is the character ':';
- then a field with an integer telling you how many RNs are available in the appliance buffer, ready to be requested;
- a newline ( '\n' ) ends the message.
- Example:
52:3473460:1384\n
- You can terminate the connection with the command:
end
- At the moment, concurrent access is not supported (aka I don't need it for now), so, closing the connection also permits different client to connect;
- Raspberry Pi Pico SDK
- Cmake
Detailed instruction for dependencies installation are available on Raspberry website.
- Before compiling, is required to edit wifi_credential.hpp inserting Wifi SSID and password.
- compile the program as follow (set -DPICO_SDK_PATH using real pico-sdk path):
cd build
make -f makefile.srv all
- deploy the generated binary file named:
geiger_gen3.uf2
putting the Pico in "deploy mode" pushing the white button before connecting USB cable and releasing the same button a second after the connection.
- A trivial Python client example is present in "test" directory in the present software distribution.
- The number can be requested from any program able to create Berkeley sockets using the described protocol.
- Thanks to Teviso company (https://www.teviso.com) that kindly provided the sensor for this project;
- Thanks to my friend Andrea ( https://github.com/btlgs2000 ) for his help to test this applicance.
- test and statistics