Projects

Problem

Bold Advanced Medical Future (BAMF) currently employs an expensive option for monitoring radiation levels in different rooms of their facility. They are limited to a maximum of four devices that can be connected to the network between the sensors. The only location for BAMF to view the current levels of the radiation detected by the radiation devices is from a wall-mounted LCD screen. It is also difficult to reconfigure existing devices on the network or adding new devices to the network. BAMF has no other option but to use their current setup to monitor rooms of higher importance, where radiation is likely to be higher. BAMF would like to be able to update their current setup, design, and network. Specifically, creating a new radiation detection sensor that can be connected to a server hosted by BAMF with a front-end user interface that can add new sensors to the network and reconfigure each individual sensor’s properties.

Solution

The current solution involves creating a new custom-made PCB that incorporates all the features desired by BAMF. The microcontroller unit (MCU) used to drive all necessary components, actions, and calculations is the ESP32-WROVER-E-N16R8. This MCU has an extended documentation on its capabilities and can perform all the required functionalities. UART and JTAG communication are both available to interface with the MCU as well as an internal MAC controller to interface with the network. The MCU is also in charge of calculating the correct effective dose measurements (Rem) that is captured by the connected Geiger-Müller (GM) tube. The MCU is to record and transfer the average Rem readings calculated per minute and update the current Rem reading every second after one minute of start-up readings.

Alongside this is an isolated high voltage supply from XP Power that the MCU will be able to drive at different input voltages to power different (GM) gamma-beta tubes used by BAMF. This high voltage supply (A2OP-5) can produce an output voltage from 100 to 2000V that is dependent on the input voltage. For safety, a 2V (Physical 3.2V clamp) clamping circuit is implemented on the input voltage side. This ensures the output voltage does not reach an unexpected level and puts a limit on the output voltage at 660 V. The PHY component (IP101) used on the prototype development kit is integrated into the final design to deliver Ethernet connection to the MCU.

With Ethernet connection to the MCU, the network connection to the server is satisfied by using web sockets along with TLS encryption protocol. The server must assign the sensor its own ID and confirm its connection status before the radiation detection device attempts to send data to the server. The custom printed circuit board (PCB) employs Power over Ethernet (PoE) capabilities by separating power and data from the RJ45 connector. A surface mounted SD card is also implemented to locally store the last 12 hours of recorded data in the case of network loss. A surface mounted electromagnetic buzzer is added to provide alarm functionality if the radiation dose measurements exceed the specified/assigned level.

Impact of a Decoupling Capacitor and Trace Length on Signal Integrity in a CMOS Inverter Circuit...Article Coming January 2024 with Bogdan Adamczyk in In Compliance Magazine

The PCB used in this demonstration is a newer version of the board used in previous article. This new PCB, contains several switches allowing the user to change the oscillator frequency, the length of power and ground traces, and choose whether to use the decoupling capacitors.

During switching a transient current is drawn from the source. The inductance associated with the current loop causes the voltages at the power and ground pins to deviate from the desired values.

The board was purposely designed with very long traces to show the negative impact of the associated inductance, while at the same time increasing the impact of a decoupling capacitor.

Further information about this board and demonstration can be found at [2] (Coming soon). This board along with Altium files for this design can be found in Professor Adamczyk Newest book [3].

References

[1] Bogdan Adamczyk, Impact of a Decoupling Capacitor in a CMOS Inverter Circuit, In Compliance Magazine, September 2019.

[2] Bogdan Adamczyk, Impact of a Decoupling Capacitor in a CMOS Inverter Circuit, In Compliance Magazine, January 2024.

[3] Bogdan Adamczyk, Principles of Electromagnetic Compatibility: Laboratory Exercises and Lectures, Wiley, 2024.

Links

January 1, 2024 - Impact of a Decoupling Capacitor and Trace Length on Signal Integrity in a CMOS Inverter Circuit

March 1, 2024 - Impact of Decoupling Capacitors and Trace Length on Radiated Emissions in a CMOS Inverter Circuit

April 1, 2024 - Impact of Decoupling Capacitors and Trace Length on Conducted Emissions in a CMOS Inverter Circuit

The PCB used in this designed for this demonstration was design for a practical exercise that can aid in the understanding of current paths of a micro strip containing discontinuities. This new PCB, contains a singular trace that is connected to a signal generator. With a near field probe one can measure the emissions of a microstrip with differing ground plane discontinuities. When varying frequencies the return current path can be observed to change around each discontinuity. 

This board along with Altium files for this design can be found in Professor Adamczyk Newest book [1].

References

[1] Bogdan Adamczyk, Principles of Electromagnetic Compatibility: Laboratory Exercises and Lectures, Wiley, 2024.

This hardware experiment demonstrates the impact of the return path impedance and the return current level on common-impedance coupling between circuits. The measurements are performed on a custom PCB, containing audio, video, and high current circuitry where the return paths for each circuit can be selectively shared with other circuits. 

This board along with Altium files for this design can be found in Professor Adamczyk Newest book [1].

References

[1] Bogdan Adamczyk, Principles of Electromagnetic Compatibility: Laboratory Exercises and Lectures, Wiley, 2024.

Links

August 1, 2024 - Common-Impedance Coupling

This project is the first set of PCBs designed for an embedded weather station project. The targeted MCU used in this project is the RP2040 that interfaces with a BME280 Temp/Humidity/Pressure sensor. Intended to be the first step in the series of boards. Following steps as a result of this board will be to interface with a Wi-Fi chip to upload data gathered from the BME280 and confirm proper Wi-Fi interfacing. 

This board was designed to be a prototype to confirm layout and initial design on the RP2050.