Author: jwruffle

At the start of the week on Sunday, I worked with Sherry and Olek on the final presentation slides. On Tuesday Olek and I figured out a way to mount the force sensitive resistors on the inside of the keyboard such that the user can play the keyboard normally without worrying about exactly hitting the sensors. I ordered clincher connectors to wire up the sensors, as it is not advised to solder directly to the tabs. These connectors are a bit finnicky, however, so I spent some time improving the connectors’ connections to the sensors. Afterwards I mounted the sensors to the underside of the keys and routed the wires out the back of the keyboard through a hole that Olek and I drilled previously. Lastly, Sherry, Max and I worked to write up the final poster PPT on Thursday.

For the upcoming week, I will work to prepare for the final demo on Monday. I still need to clean up the wiring from the sensors to the PCB as well wire up a start, stop, and pause button on a breadboard which shouldn’t take too much time. I will complete these tasks tomorrow (Sunday). I believe I am on schedule but will start these tasks early afternoon tomorrow in case anything goes amiss. Lastly I will work with my teammates to write the final report due next Friday.

This past week since coming back from Thanksgiving break, I received all the parts necessary to reflow my sensor data collection PCB. I spent three hours on Tuesday and about an hour on Wednesday reflowing the board as well as soldering on the through hole components. I realized that I had the wrong package for some resistors so I found alternative resistors of the same value and reflowed the board. I also ended up needing to rework the board when I realized all of my diodes were backwards and some parts weren’t making good contact with the metal pads. On Thursday I finished reworking the board and validated that the power conversion circuitry and the rest of the board worked well aside from the ADC I2C communication. I am using an 8 channel 12 bit ADC I2C IC that takes in 8 channels of analog data and outputs them over I2C over the SDA pin. Due to this, I  needed to collaborate with Olek to validate the functionality of the chip with the Raspberry Pi that requests data over I2C.

On Friday night I met with Olek for a few hours and the two of us attempted to bring up the I2C communication between the sensors and the Raspberry Pi. We were using the oscilloscope to view the SDA and SCL lines, but did not find it particularly useful or insightful as we were seeing weird behaviors. We met again on Saturday for another couple hours and were able to establish communication over I2C between the PCB and the Raspberry Pi! I think it was because the Raspberry Pi GND and the PCB’s digital ground were not coupled, so the I2C communication wasn’t being established properly. I also validated that the buzzer emits a tone when 3.3V is applied. The last thing I need to do is validate the binary coded decimal rotary switch works correctly, which shouldn’t take long. Currently Olek is working on how to request data from all 8 channels of the ADC and how to generate the PWM signal for the buzzer using the binary coded decimal rotary switch position.

For the upcoming week, I will work on the final presentation slides for Monday as well as work on the final poster due on Thursday. Additionally, I will work to mount the sensors onto the piano keys before Monday in order to take a nice video for the final presentation 🙂 Lastly, I want to validate the rotary switch function and replace some resistors on the PCB such that the indicator LED’s for the key presses are more bright. I believe I am exactly on schedule and can finish my tasks before the final presentation on Monday.

This week our team worked on slides and presented for the interim demo. Olek and I also worked together on Wednesday evening to set up an Arduino to communicate over I2C with the Raspberry Pi.

This week I finalized the sensor data schematics and finished the layout of the board. I generated the gerber files and the bill of materials and uploaded them to PCBway to receive a quote which came out to around $82 not including shipping. I am currently waiting for PCBway to review the board so that I can order it. I am behind schedule, so in order to receive and debug the board in time I am planning on paying for the board to be manufactured out of house and for expedited shipping using our remaining budget.

My goals for the week are to have the PCB design approved, ordered, receive the board, and start testing it and integrating it with the Raspberry Pi for the final showcase.

ABET #6 says … An ability to develop and conduct appropriate experimentation, analyze and interpret data, and use engineering judgment to draw conclusions

Now that you are entering into the verification and validation phase of your project, provide a comprehensive update on what tests you have run or are planning to run.  In particular, how will you analyze the anticipated measured results to verify your contribution to the project meets the engineering design requirements or the use case requirements?

Thus far, I have simulated a simple sensing circuit using the force sensing resistor sensors, potentiometers, and an LED. I tested different values for the potentiometer to ensure that the voltage output would cover the full range of the ADC. I found a value for the potentiometer that covers as much voltage range as possible whilst also illuminating the LED.

When the pressure sensor data collection board arrives, first I will test the power conversion circuitry to make sure my 5V and 3V3 rails are working. Then I’ll test that the ADC I2C chip is working correctly by ensuring the Raspberry Pi is receiving I2C packets from the PCB. Then I’ll mess around with the sensors to see if I need to change any resistance values to alter voltage levels or change my RC filter.

Over the past week, Olek and I have been working together to test the force sensing resistors. Olek set up the Raspberri Pi and I gathered the breadboard, resistors, and LEDs to test the sensors. We were able to validate that the sensor press could be detected by running a simple script that outputs a print statement when the sensor is pressed. We also tested the response time of the Raspberry Pi returning sensor data.

Additionally, I made some last minute changes and am almost done laying out the board. It took a while to get used to using Altium and learning about board layout, but it should be done by Sunday midnight and ready to order by midday Monday. I am a couple weeks behind schedule with the PCB, but to mitigate this issue I am planning on using our leftover budget to expedite the manufacturing and shipping of the PCB itself and accompanying components.

My goals for this week are to finish the layout this weekend, order the board, receive it, and get it reflowed. I want to have it finished and be ready to test by midway through the following week.

In the week leading up to the beginning of Fall Break, our team’s focus was on writing the design review report. I contributed to sections such as the Abstract, Use-Case Requirements, and the relevant hardware sections within the Design Requirements, Design Trade Studies, System Implementation, and Test, Verification, and Validation sections. I also contributed to the Bill of Materials and Schedule sections.

Over Fall Break, I finished the schematics and started the board layout which means that I am behind schedule on the hardware portion of my work. I meant to finish the layout and order the board during Fall Break, but certain things came up preventing me from doing so. To mitigate this issue, I will work for the next couple of days to finalize the board and during the time when it is being fabricated and shipped to me, I will work on bringing up the Raspberry Pi so that the two can easily interface once the PCB arrives.

My goals for this coming week are to finish the board layout and order it, as well as finish setting up the Raspberry Pi with a monitor and keyboard. Finally, I want to set up a simple I2C polling procedure code with the Raspberry Pi.

As you’ve now established a set of sub-systems necessary to implement your project, what new tools are you looking into learning so you are able to accomplish your planned tasks?

One tool that I have put many hours into learning for this project is Altium Designer, which is a PCB design software. I had no experience with Altium before this course, and minimal exposure to PCB schematics and layout. Additionally, I am learning how to interface with the Raspberry Pi which is also new to me.  In regards to writing code for the Raspberry Pi, I have been learning more about Python packages that are available to me for  communication with I2C devices.