Senior Design
In my senior design projects class, we designed a device designed to measure the fluid composition within an oil pipeline while maintaining a flush inner surface using a radome to avoid fluid flow discontinuities and restrictions. The FlowProbe consists of three main parts; a sensing structure, vector network analyzer (VNA) and power control unit.
The sensing structure consists mainly of a probe and resonator that transmits a narrow frequency sweep that permeates into the pipe. As the fluid in the pipe changes, the resonant frequency changes because it sees a change in impedance. The change in impedance correlates to the difference in phase of the transmitted and reflected signal, which is what we measure.
The VNA generates a frequency sweep for the sensing structure. To achieve this, the microcontroller (MSP432) inputs a varying pulse-width modulated (PWM) signal into a digital to analog converter (DAC). The DAC outputs a stable DC voltage based on the duty cycle of the PWM signal which is then used by a voltage controlled oscillator (VCO) to generate a frequency that is sent to the probe. This frequency is swept across an narrow frequency range centered around 400 MHz. The device the uses a AD8302 integrated circuit to measure the phase difference between the source signal and the reflected signal.
My team and I all designed the overall block diagram of the device, but I was the one responsible for selecting the specific components used, designing circuit/schematic, and designing and creating the layout for the PCB in Altium. This was a two-layer board and we made two revisions of it. After the second revision, every function and subsystem worked as we designed, and our project demonstrated a proof-of-concept of our design. I also wrote the python program responsible for the processing and plotting of the data received by the device, and was heavily involved with the embedded programming of the MSP432.
PCB Design & Manufacturing
In this course, I designed, along with two others, a PCB that included the following features: microcontroller (MSP432 ARM-Cortex M4), USB, UART IC (FT232), JTAG, bluetooth module (Microchip RN4871), LCD display & touchscreen ADC (14-Bit, up to 1 Msps), joystick, and several buttons. In the limited time that we were able to get all of the features working at a basic level. We got the touchscreen to display simple graphics and respond to touch input, we got the bluetooth to communicate with an android, got the usb to communicate with serial port on a PC, and go the buttons and joystick to function properly. This was a 4-layer board that we designed in two revisions.
CU Maxwell Cubesat
CU Maxwell is one of CU Boulder's cubesat teams that I participated in for two semesters. On the team, I designed a board that was designed to debug all of the different subsystems on the satellite. It used 8 serial to usb converters to send data from the boards from the cubesat subsystems to a PC. Another board I designed was a motor driver board that is used to control motors that extend a deployable antenna array for the satellite. Because of NDA agreements, I am not allowed to disclose of specific design details or provide images of the PCBs.