This device is Geiger-Muller Counter ,and True Random Number Generator(TRNG) uses radioactive isotopes.
- Radiation Detection - CPS, CPM, uSv/h, mSv/Y
- Temperature - degree Celsius (°C)
- True Random Number Generator - Serial Port Output 8bit TRNG
- Geiger-Muller Tube - J321βγ, M4011, SBM-20...etc
- MSP430G2433 or MSP430G2553
- TLC555 (CMOS 555, DIP or SMD)
- TMP35 (Operate Voltage 3.3v)
- Fuse Holder on PCB for T5x20 Size * 2
- J1 - CMOS555 4.2v power supply.
- VR1 - Adjust High-Voltage output 180VDC~500VDC, DMM setting 1000VDC internal resistance = 10M, if you measure tube voltage around 250VDC you're doing fine(real voltage 400VDC).
- IC1 - if this is use LDO, your temperature sensor power supply voltage = 2.9v-3v(TMP35), use forward voltage(VF) 0.5v diode, temperature sensor power supply voltage = 3.7v-4v(LM35).
For J321βγ, it doesn't happen often, I guess that's about wavelength of light.
- Install Energia 1.6.10E18
- Select board -> MSP430G2553
- Open MSP430Geiger.ino
- Connect Debugger BSL to MSP430Geiger
- Upload
- Done
How to calculate calibration factor? Reference Method1,2,3,4 (SBM-20 = 175, M4011 or J321βγ = 153.8)
const float CPM2uSv = 153.8f; //CPM to uSv/h conversion rate
R19, R20 is 10k and 33k, LM321 gain = 1+(33k/10k) = 4.3, so original temperature voltage: temp_vol = (ADC/4.3) * (3.3/1024), every 10mV(TMP35, LM35) = 1°C, temperature = temp_vol / 0.01 °C.
const float TEMPERATURE_GAIN = 1.0f + 3.3f; // 1+ (33k/10k)
const float ADC2VOL = (3.3f/1024.0f); // 3.3v/10bit
If detected ionizing radiation MSP430G4 P1_4 interrupt count += 1.
CPM_TIME_PERIOD 20-second sampling-rate for count-per-minute calculate, CPM = 60sec/20sec * count;
const unsigned long CPM_TIME_PERIOD = 20;
Next, converting CPM to a Dose Unit.
uSv/h = CPM / CPM2uSv(153.8);
mSv/Y = uSv/h * 24(Day-Hour) * 365(Year-Day)
The worldwide average natural dose to humans is about 2.4 mSv/Y.
Calculate pulse-to-pulse time period of every three counts, if (C2-C1) > (C3-C2) output current bit 0 value, (C2-C1) <= (C3-C2) output current bit 1 value, this process is physically random.
/* pseudo code */
pulse_diff_time_array[3] = {C1,C2,C3};
T1 = C2-C1;
T2 = C3-C2;
if(T1 > T2){
random_number |= (0 <<= random_number_size);
}
if(T1 <= T2){
random_number |= (1 <<= random_number_size);
}
++random_number_size;
if(random_number_size == 8){
Serial Output random_number;
random_number = 0;
random_number_size = 0;
}
MIT License
Copyright (c) 2020 Tony Guo https://github.com/GCY
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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