---
title: "a Low-Cost IoT Gamma-Ray Spectrometer with the Easy-F407V-ETH (W5500) Board"
url: "https://maker.wiznet.io/TheoIm/projects/a-low-cost-iot-gamma-ray-spectrometer-with-the-easy-f407v-eth-w5500-board/"
markdown_url: "https://maker.wiznet.io/TheoIm/projects/a-low-cost-iot-gamma-ray-spectrometer-with-the-easy-f407v-eth-w5500-board/md"
type: "UCC: User Created Content"
author: "GSCh"
author_url: "https://blog.naver.com/tery1312/222677606400"
editor: "WIZnet"
editor_url: "https://maker.wiznet.io/"
original_author: "GSCh"
original_url: "https://blog.naver.com/tery1312/222677606400"
published: "2025-11-18"
language: "en"
hardware: ["WIZnet W5500"]
likes: 0
views: 437
comments: 0
source: "WIZnet Makers (https://maker.wiznet.io/)"
---

# a Low-Cost IoT Gamma-Ray Spectrometer with the Easy-F407V-ETH (W5500) Board

> A low-cost IoT gamma-ray spectrometer built with STM32F407 and WIZnet W5500, streaming real-time radiation spectra to a PC.

Original author: GSCh (source: https://blog.naver.com/tery1312/222677606400)

## Components

- **WIZnet W5500** x 1 ([docs](https://docs.wiznet.io/Product/Chip/Ethernet/W5500))

WIZnet parts: W5500 ([Datasheet](https://docs.wiznet.io/Product/Chip/Ethernet/W5500/datasheet?utm_source=maker&utm_medium=project&utm_campaign=w5500), [product hub](https://maker.wiznet.io/products/w5500/))

## Article

**The W5500's role is transformative**: It converts a standalone analyzer into a **networked IoT instrument**—opening applications in remote monitoring, distributed sensor networks, and cloud-based radiation surveillance systems.

- **STM32F407**: High-speed ADC + DMA for gamma pulse measurement

- **W5500 Ethernet**: Real-time spectrum streaming to PC

This combination enables real-time analysis of hundreds to thousands of radiation events, displaying live gamma spectra on a PC screen.

---

## 1. System Concept – How a Gamma Spectrometer Works

![](https://maker.wiznet.io/upload/ckeditor5/1071063072%5F1764261066%2Epng)

![](https://maker.wiznet.io/upload/ckeditor5/1071063072%5F1764261083%2Epng)

Gamma rays are invisible, so they must be converted into energy values through the following stages:

### ① Scintillator — Gamma → Light

When gamma rays enter a crystal such as NaI(Tl), a brief light flash occurs. The brightness of the flash corresponds to the gamma-ray energy.

### ② PMT (Photomultiplier Tube) — Light → Voltage

Amplifies faint light by millions of times, resulting in an electrical pulse of several volts. Requires high voltage (500-1000V).

### ③ Analog Conditioning — Clean Pulse

Preamplifier + shaping amplifier refine the signal into a clean Gaussian pulse that the STM32 can read effectively.

**Result**: Each gamma-ray event is represented as a single pulse, where the peak height equals the gamma-ray energy.

---

## 2. STM32F407 – Ultra-Fast Pulse Processing Core

The performance of this project is determined by the STM32F4's 12-bit ADC + DMA + EXTI combination.

![](https://maker.wiznet.io/upload/ckeditor5/397665397%5F1763473917%2Epng)

### High-Speed Capture Pipeline

```plaintext
Amplifier Output → ADC (PA0) → DMA Circular Buffer → EXTI Trigger →  
Pulse Peak Detection → Histogram Binning
```

### Technical Core: NDTR-Based Buffer Indexing Algorithm

The key challenge is locating where a newly arrived pulse resides in the DMA circular buffer. Using NDTR (Number of Data Transfer Remaining), the system:

- Immediately calculates pulse position

- Averages surrounding samples

- Accurately detects peaks

**Before algorithm optimization**: Spectrum peaks were blurred
**After optimization**: Very sharp energy peaks (experimentally validated)

**Processing Speed**: ~8 µs per event analysis

---

## 3. W5500 Ethernet – Turning It into an IoT Scientific Instrument

This spectrometer transcends a simple MCU project, expanding into a network-based real-time measurement device.

### W5500's Role

- **TCP/IP Offload**: Minimizes MCU load

- **Stable Streaming**: Handles thousands of events per second

- **Immediate PC Plotting**: Ensures transmission speed for real-time visualization

- **IoT Measurement**: Enables networked instrumentation without OS or Linux

With W5500, the system becomes a complete **Real-Time Radiation Spectrum Monitoring Device**.

![](https://maker.wiznet.io/upload/ckeditor5/397665397%5F1763475079%2Epng)

---

## 4. Real Measured Spectra (Actual Results)

### Am-241 (Americium) – 59.5 keV Peak

![](https://maker.wiznet.io/upload/ckeditor5/397665397%5F1763474512%2Epng)

- Two distinct low-energy peaks

- Exact match with theoretical values

- Validates proper MCA functionality

### Lu₂O₃ (Natural Lutetium)

![](https://maker.wiznet.io/upload/ckeditor5/397665397%5F1763474648%2Epng)

- **Expected peaks**: 202 keV, 307 keV

- **Measured**: Strong peak at ~200, secondary peak near ~300, similar 509 keV composite peak structure

- Matches characteristic pattern of natural lutetium samples

### Uranyl Nitrate (Uranium Compound)

![](https://maker.wiznet.io/upload/ckeditor5/397665397%5F1763474702%2Epng)

- **Characteristics**: Sharp peak in low-energy region, gradual distribution in mid-energy range, long tail structure

- Highly similar to typical spectrum of natural uranium compounds

### Unknown "Anion Powder" Sample

![](https://maker.wiznet.io/upload/ckeditor5/397665397%5F1763474791%2Epng)

- **Results**: Clear low-energy peak, multiple mid-range bumps, continuous tail

- Confirms presence of natural radioactivity

- Not a single isotope, but sufficient for "radioactive material presence detection"

---

## 5. Easy-F407V-ETH Board – Custom Hardware Design

| Component | Role |
| --- | --- |
| STM32F407VET6 | High-speed ADC + pulse processing |
| W5500 | Hardware TCP/IP Ethernet |
| Clean analog routing | Prevents PMT/AMP signal degradation |
| Compact board | Optimized for lab/field testing |

The board is not just a development platform but a carefully designed **experimental measurement instrument platform** that harmonizes analog signal processing, high-speed MCU, and networking.

---

## Why This Project Is Important

This project is a rare case that fuses two domains:

### 1) Professional-Grade Physics Experimental Equipment (Gamma-Ray Spectrometer)

- Actual isotope identification capability

- Real-time energy histogram generation

### 2) IoT-Based Real-Time Measurement (Streaming MCA)

- Networked instrumentation using W5500

- Remote monitoring and data collection capability

- Low-cost educational and research equipment fabrication

---

## Conclusion

This project demonstrates the following:

**✔ STM32F4's DMA + high-speed ADC alone can implement a professional MCA (spectrometer)✔ Combined with W5500 Ethernet, it achieves functionality comparable to Networked Radiation Monitoring Devices used in research institutions✔ Even with low-cost open hardware, it achieves scientific precision capable of properly distinguishing spectra of Am-241, Lu₂O₃, Uranium, and more**

---

## Final Summary

- **IoT radiation analysis equipment** ready for immediate use in education, research, and scientific experiments

- **Validated project** with clearly detected actual isotope spectra

- **Engineering completeness** with high-speed DMA + NDTR algorithm implementation

- **Complete IoT measurement platform** with W5500-based real-time streaming

- **Rare-quality project** that is low-cost DIY yet possesses professional functionality

---

Source: https://maker.wiznet.io/TheoIm/projects/a-low-cost-iot-gamma-ray-spectrometer-with-the-easy-f407v-eth-w5500-board/