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Nick Status Report 4/12

The past two weeks, I have assisted with verifying the circuit for the PCB, made the interface code for the pedal, created test codes for debugging the pedal, met with Chaitanya to debug the interface code, modified the plans for the 3d model due to changes with the PCB, and made designs for the input circuit. The interface code is mostly working, with only the buttons and the rotary encoder still having issues, but this is likely due to some confusion with the Daisy library, as the classes for switches and encoders seemingly are in progress. I have already made some alternate files to test possible solutions and am working on making versions of the code that use the standard GPIO class, which we know works as I used it for the other components, but I am hoping that we can get the Daisy classes working as their debounce function would likely work better for our pedal. For the 3D model, after learning that the PCB size would be much larger than initially planned, I remade the models to fit the new PCB and sliced them, and it seems that the base at this new size would be too expensive to print, so I moved the holes for connections in the base to the faceplate, and will find a premade plastic box that we can use as the base. Overall, this shouldn’t affect the functionality. Our progress seems to be slightly behind, although not by much, as we should be able to catch up early in the week and hopefully start testing. Next week, I will fix the last few things with the interface code, add the holes to the faceplate model and send it for printing, finalize the breadboard version of the circuit for testing, start testing once the audio processing code is fully converted to C++, do my part of the presentation slides, and prepare for the presentation.

As for testing of my own subsystems, as of now, I made most of the circuit in tinkercad while we were designing to test functionality and have made and modified multiple test files for the interface code to debug the individual subsystems of the interface. For the tests I plan to do in addition to the tests we are doing on the whole system as discussed in the team report, I plan to test the system with the full code and compare it to a preset input with just the audio code to determine if there is any significant impact from the interface code on latency, and plan to test the overall noise impact of some of the changes in our design.

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Frantz’s Status Report for April 12

This Week’s Accomplishments:

This week, I spent a lot of time working on my C++ code, to be loaded onto our microcontroller. I have completed most, but not all of the real-time pitch-shifting algorithm, with quite a few roadblocks. The first was that I found great difficulty in importing a library for computing the Direct Fourier Transform. In order to minimize the difficulty of interacting with a new interface, I wrote my own DFT code myself, following the Cooley-Tukey radix-2 algorithm. I also wrote code for the Inverse Direct Fourier Transform, which was a simple edit of the DFT code.

Here is my current DFT code, with some print debugging commented out:

I have not yet optimized my code for quickness or implemented garbage collection, which will be necessary for programming in C++. However, I have tested my code and found that for a few test inputs, my output matches that of the Python function “numpy.fft.fft”.

I have found some difficulty in converting my previous Python algorithm not just into C++ but into a real-time operation. This is still in-progress. I will need to test my code’s performance to ascertain what amount of latency is safe.

I have used the micro-USB cable I ordered to connect our microcontroller to my laptop. Next week, I aim to start by learning how to use the Daisy Library to receive input samples and send output samples. I will then implement the “delay” functionality, which is comparatively simple.

We are somewhat behind our original schedule and a little pressed for time. Nevertheless, we are confident in our ability to complete our project in the next week. I will spend a lot of time completing and testing my code within the next few days.

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Frantz’s Status Report for March 29

This Week’s Accomplishments:

This week, I began programming in C++. I first created functions to extract samples from a .wav file and create a new .wav file using a list of samples. This allows us to easily test our algorithms using imported sound files. Then, I began reworking the pitch-shifting algorithm in C++. I am modifying it so it completes the task in chunks, which is vital for outputting data in real time with minimal latency. I tried importing the FFT library “shy_fft,” but it doesn’t seem to work properly. After a lot of troubleshooting, I switched to “FFTW.”

Additionally, I ordered a micro-USB cable with data transmission for connecting our microcontroller to a computer.

Status:

Our schedule is on track, but time is getting tight. We will stay diligent to complete our project satisfactorily.

Next Week:

Next week, I will continue rewriting the phase vocoder algorithm for real-time use in C++. I will test the FFTW import to ensure that it works properly. When I am done, I will start writing the delay algorithm.

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Nick Status Report 3/29

This week, I was unable to work much, as I was sick and had a major lab for another class. With the time I had, I researched some other daisy projects to make a plan for the device code for our pedal, so that we can start integrating everything. My progress is slightly behind because of the setbacks from this week, but I have plenty of time in the next two weeks to make up for it. Next week, I hope to get the base of the main code done so that we can test the code Chaitanya has been working on with our audio processing code, and I also hope to get the 3D model finished if the PCB is done in time.

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Team Status Report for March 29

Primary risks involve not being able to get the systems integrated on time. Josie has made good progress prototyping the pitch shifting and delay features in python and is working to get them in C++ for the microcontroller. Chaitanya is looking to wrap up prototyping with the Daisy Seed and I/O components on breadboard in the coming week. Nick has preliminary casing 3-d models. The integration of these different parts will, therefore, be our next challenge. We are looking to address this next week once all of the different subsystems are fully functional. This will involve extensive discussion on the interfaces of our separate modules and a push in the next few weeks to experiment amongst our different parts.

No changes to the existing design. Potential changes could be made to the hardware in case there isn’t enough time for the PCB and the breadboard implementation is working (which seems to be the case at this point). Schedule should be sufficient but we will be heavily emphasizing system integration in this final chapter of our project. Please reference individual status reports for detailed pictures/diagrams of our individual progress.

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Chaitanya’s Status Report for March 29

This week, I continued working on the PCB design. I attempted to resolve issues regarding the pinouts provided on the data sheet with Gordon but decided that testing of the physical component was the most efficient way of matching the schematic pins to physical pins for components that had vague data sheets. However, since there was an extensive delay in getting our components despite putting an order weeks ago (just got them on Wednesday), my progress at the beginning of the week was hindered. Once I got the components, I immediately started on the breadboard prototype. My goal for this week was to understand the pinouts of all components and set up the breadboard prototype with the daisy seed mounted. I was able to successfully test and identify the the functionality of all pins for all components. I did this using the DC power supplies in Tech Spark and an LED to verify that buttons, switches, and 7-segment display were working. Here is my current progress on the breadboard. The headerpins came with the daisy seed. We originally ordered a non-soldered microcontroller, but ordered another one recently with soldered header pins.

The delay in getting the components halted my progress on the PCB as I couldn’t proceed for some of the buttons until I was confident which pins in the schematic corresponded to the schematic pins. It also delayed my progress on the prototype. Hence, I am slightly behind schedule. My plan is to establish a connection between the daisy seed (goes on top of the header pins in the picture) and the I/O components by displaying print statements everytime an interaction with a button, switch, etc. occurs. I would like to be able to demo this during next week’s interim demos. However, we are also waiting on the the micro-usb cable used to program the Daisy. We had originally thought we placed an order, but when it didn’t come with the rest of the components, we realized that it was not placed and immediately placed another one. I strongly believe that my connections in the picture above are correct as I tested them with DC power supply/LED successfully. Hence, the primary concern is familiarizing myself with the daisy interface. While Josie will be primarily in charge of the 2 features of our pedal and getting them working with the microcontroller, I need to be able to program I/O features using the interface.

Given the limited amount of time we have at this stage, I will be heavily investing my time in getting a breadboard prototype fully functional over the next week. The PCB will serve as a bonus version of the prototype but getting a basic implementation working is my first priority. Once I am able to set up the Daisy Seed GPIO connections, I hope to resume work on the PCB, fixing the connections in the schematic/layout according to the testing of the physical pins I completed this week and early next week.

 

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Frantz’s Status Report for March 22

This Week’s Accomplishments:

This week, I have written the phase vocoder algorithm in Python. It successfully shifts our test tone by a given number of semitones up or down. There are currently some harmonics introduced in the process that I will need to debug, but the output is coherent. I also tested the input levels coming out of a guitar using an oscilloscope. I noticed that there is a significant amount of noise above the threshold of human hearing. So, we decided that we can use a simple RC filter to remove the noise before the signal gets input into the Daisy Seed. This should avoid any issues with aliasing. We also completed part of the Ethics Assignment this week.

Status:

Now that the phase vocoder pitch shifter works, progress is back on track.

Next Week:

Next week, I will start rewriting the phase vocoder algorithm in C++. Notably, for real-time input, I will need to use a circular buffer to store the signal while each batch is being operated upon. I will determine if I need to write a fast Fourier transform algorithm or if we can import a (or use an already-imported) library.

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Nick Status Report 3/22

 

This week, we started by doing part 4 of the ethics assignment Monday. Then, I made the base of the 3D model for the pedal housing to confirm the initial design ideas with the group Wednesday. I can’t add the holes for the components yet, as the PCB layout isn’t complete yet, and will be mounted to the other side of the faceplate, but I discussed more with the 3D printing lab to ask about restrictions and design requirements so that I can add the I/O holes and send out the designs for printing once the PCB is finished. In lab Wednesday, we discussed the initial model and tested our audio input component to find if we needed to make any adjustments to our schematic. I also worked with Chaitanya further to fix some issues we had with the design, swapping out some parts and adding some components to deal with pin issues on our microcontroller. We are mostly on schedule, although we are having to shift some parts of the schedule around due to some work relying on other work to be completed. Next week, I will start on the implementation software, although one of my other classes has a major lab that will keep me busy early in the week.

 

 

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Chaitanya’s Status Report for March 22

This week was dedicated to making solid progress on the PCB. We wanted to get the parts ideally by this week as the order was placed last week. Ideally, we wanted to have an initial prototype done on the breadboard this week to use as input to the PCB before sending it off. As I worked through the PCB schematic, I realized that the number of GPIO pins might be a limiting factor to the pedal surface I/O that we had. Hence, we reduced the number of pitch shifting buttons from 4 to 2. Originally, we had 2 buttons for +/-1 octave and +/-1 semitone pitch shifting. I decided to remove the +/-1 octave buttons to free up some GPIO pins. After discussing with Nick, he also looked into 7-segment displays with potentially less pins. He found a 12-pin display that I downloaded an updated my schematic with. I was able to go through the datasheet for each component and figure out which pins corresponded to what functionality. After doing so, I was able to make the appropriate connections to the Daisy Seed microcontroller. I was able to get the schematic done for the pitch adjustment buttons, mode switch, and beat/pitch LED buttons rotary encoders, and ON/OFF LED. I also realized that I needed pull-up and pull-down resistors to make sure that I was sending good 1’s and 0’s. I added these in, adding 10kOhm resistors going into the GPIO pins and 10kOhm resistors for switch pins that were not ON. Please see the my current schematic progress:

I think my progress is back on track. I had doubts last week given my unfamiliarity with KiCad, but I spent a lot of time this week watching tutorials and reading the datasheets multiple times to get a solid understanding of the hookups. After getting most of the schematic done, I am more confident in the timeline to get the PCB out.

I still have to quickly do the hookups for the 7-segment display and 2-mode switch for selecting 3 vs. 4 beats. I have already looked through the datasheets to verify that the parts are good and that I have a solid understanding of the pins in the schematic. My next steps are to clarify some of the datasheet pinouts to make sure my hookups are correct. I will set up a time with Gordon early next week and finalize the schematic shortly after. Once this is done, I need to quickly place and route in the layout view and use Gordan’s help to get the PCB out as soon as possible. Hopefully, by the end of next week, I should have a nearly complete layout that can be sent out.

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Team Status Report for March 22

Most of our risks still lie in the PCB manufacturing. Chaitanya is working to get the PCB schematic/layout out. We are mitigating this risk by having a functional breadboard-based implementation. All components have been ordered over a week ago, and we should have them early next week to make connections. The risks on the software side lie primarily in making our code compatible with the Daisy Seed microcontroller. Josie has been able to get functioning pitch shifting and delay algorithms to work using Python. The group was able to verify that the functionality of these algorithms. Adapting these algorithms to meet the Daisy Seed specs is the primary concern. We will have to make sure we are comfortable using memory and any other blocks on the Daisy. Having a working prototype in python is our main form of mitigation as it gives us a base for developing our C++ program for the microcontroller.

A few changes were made on the hardware side. With a lot of the schematic done for the PCB, we realized that there may not be sufficient GPIO pins for all of our components. Hence, we made a few small modifications to the user interface of the pedal (buttons, switches, etc. on the outer surface of the pedal casing). This included reducing the buttons the user can use to specify the amount to pitch shift. Previously our design had 4 buttons – 2 for shifting by +/-1 octaves and 2 for shifting +/-1 semitones. We removed the octave buttons. While a slight inconvenience to the user, functionality is preserved. In addition, we found a 7-segment display that required fewer pins to ensure that it didn’t take up an unnecessary number of GPIO pins on the microcontroller. These changes should not impact functionality, so we deemed them appropriate. These changes have not impacted our timeline as the PCB has not been sent out yet. Please reference individual status reports for progress screenshots.