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30 lines
2.5 KiB
Markdown
30 lines
2.5 KiB
Markdown
# IoT Geiger Counter with ESP32, OLED Display and Thingspeak Channel
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- Measures radioactive gamma and beta radiation with already quite good resolution at the typical low levels of the background radiation (due to the big STS-6 tube)
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- Displays the current counts per minute (CPM), estimated dose equivalent rate in micro-Sievert per hour (µS/h) and 10 minutes history with 5 second resolution as bargraph
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- Low-power mode for use with batteries, OLED display and click sounds on, WiFi off
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- WiFi mode for thingspeak data upload every minute, see https://thingspeak.com/channels/758223
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[](https://thingspeak.com/channels/758223)
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Feel free to use this project as a base for your own projects AT YOUR OWN RISK!
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# Hardware
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- Russian Geiger counter tube STS-6 at 400 V with ~5 MΩ series resistor
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- High voltage circuit from ArnoR at mikrocontroller.net https://www.mikrocontroller.net/topic/380666, schematic https://www.mikrocontroller.net/attachment/273334/HystereseStepUpTLC555-2.png. *Keep the high-voltage capacitor small to avoid dangerous charges! For safety avoid any contact with the high voltage parts!*
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- ~400 µs pulse generation using Geiger tube series resistors as voltage divider, high impedance input to darlington transistor and TLC 555 timer for rectangle pulse generation
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- ESP32 board Wemos Lolin32
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- OLED 128x64 with controller SH1106 at I2C
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- Voltage supply from either USB or power supply or 3x 1.5V AAA batteries, circuit works from 3.0 V up to 5.0 V
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- Pulse input is expected at GPIO 18 (high pulses with at least about 250 µs length)
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- Switch for WiFi mode is expected at GPIO 4 (low=WiFi mode, high=low-power mode)
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- OLED I2C bus is expected at GPIO 22 (SCK) and 21 (SDA)
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# Software
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- Eclipse sloeber project using Arduino library, ESP-IDF for sleep functions and u8g2 for display output
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- Low-power mode uses light sleep, a wake-up for each signal pulse change and a wake-up every 1000 ms to update pulse statistics and OLED. This results in about 90% sleep. Could be improved using deep sleep and ULP. However, light sleep is already quite good and much easier.
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- WiFi mode uses no sleep and simple interrupts for pulse counting. Pulse statistics and OLED are updated every 1000 ms, data is sent to thingspeak every 60 s.
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- Credentials (WiFi SSID, password, thingspeak channel key) are only declared in `credentials.h` and must be defined in a `credentials.cpp`
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