Team E7: The Wand Makers

Carnegie Mellon ECE Capstone, Spring 2025 — Sharon Lai, Olina Zhang, Nadia Palar

Author: hsuanjul

Team Status Report for 4/12/2025
Posted by : hsuanjul Team Status Reports

Risks and Contingency Plans

  • Firmware Compatibility Issues : The updated firmware is compilable on different machines and we were able to successfully flash the firmware to the new PCB. However, functional issues may still occur after further testings. So far we have been able to fix the bugs, but if the plan doesn’t work, we would move back to the original firmware and build upon that.
  • Model Robustness: We reduced the data collection time of the wand to 1.5s (was 8s). This change was meant to make the device more user friendly. However, model performance became much worse than before even the validation accuracy remains high during training. We are working on capturing more data, and worse case we can increase the data collection time.
  • Verification and Validation: We are testing whether the 1.5s data collection window supports accurate gesture classification. Verification focuses on evaluating accuracy, and response time to ensure the model meets MVP requirement. For validation, we are running end-to-end tests to confirm that real user interactions with the wand reliably trigger correct IR outputs.

Design Changes & Impact

There is no design changes at this point.

Schedule Updates

No major changes were made and the schedule remains as is.

Progress / Photos

Wand (Everything put together):

Wand controlling the TV in 1300 coves with cloned signal

Please see the project GitHub.

Sharon’s Status Report for 4/12/2025
Posted by : hsuanjul Sharon's Status Reports

Accomplishments

  • Assisted Olina on CNN model: tested with various waving approaches of the gestures
  • Successfully flashed firmware to new PCB: clone function is now working. Transmitter is able to store IR signal to the external flash and is able to fetch the signal and transmit it. The signal sent out is robust and can be received by appliances. The transmitting distance is closer than we deduced from the data sheet.

Verification

  • Batterylife: turn on the wand without plugging it in. See if the LED for battery is still on after 3 hours.
  • PCB design: the design has gone through design review within team before manufacture. Functioning well so far
  • IR Transmitting and receiving: Tested IR transmission at different distance and angles to the target. The transmission is robust so far with 100% successful transmission within 5 meters and 45 degrees to the target. Failure on transmission largely increase when transmission happens out of this range. I will perform more quantitative test on the transmission later and summarize a more reliable data to compare with our 80% target.

Schedule Update

I remain on track.

Plans For Next Week

Print new wand case for final review.

Team Status Report for 3/29/2025
Posted by : hsuanjul Team Status Reports

Risks and Contingency Plans

  • Firmware Compatibility Issues : The updated firmware is compilable on different machines and we were able to successfully flash the firmware to the new PCB. However, functional issues may still occur after further testings. So far we have been able to fix the bugs, but if the plan doesn’t work, we would move back to the original firmware and build upon that.
  • Product quality : The prototype we currently have may break after a lot of trials. We have been collecting data to train model using our version 1 PCB, and noticeable damage has been caused (one of the buttons is no longer sensitive and the battery port is falling off. We are trying to do most of the testing and trainings on version 1 PCB and development board so that our version 2 PCB remains new.

Design Changes & Impact

There is no design changes at this point. We are working on integrating everything and preparing for the interim design review

Schedule Updates

No major changes were made and the schedule remains as is.

Progress / Photos

Fixed wand button: https://youtu.be/jqVDue59yyQ

New PCB (with close up of through-hole for wire connection to IR LED):

Please see the project GitHub.

Sharon’s Status Report for 3/29/2025
Posted by : hsuanjul Sharon's Status Reports

Accomplishments

  • Assisted Olina on CNN model: tested with various waving approaches of the gestures
  • Successfully flashed firmware to new PCB: resolved version conflicts and weird errors across different laptops.
  • Integrated new model: Confirmed that it is safe to reduce buffer size to 7K (7*1024), given that the model size was reduced by a noticeable amount
  • Adjusted the printed wand model: fixed the button problem of easily being jammed and false long press

Schedule Update

I remain on track. Will be able to showcase at least one type of IR transforming with the wand fully assembled during the interim design review.

Plans For Next Week

Perform minor updates to our design and focus on the interim review. Print new wand case for final review if needed. Update and place the receiver PCB if needed.

Team Status Report for 3/15/2025
Posted by : hsuanjul Team Status Reports

Risks and Contingency Plans

Although there haven’t been a lot of major changes to the updated PCB, we might still encounter bugs when integrating it with the new PCB. At this point the most vulnerable part of the project is the firmware, and Nadia and Sharon are devoting most of the time to it. The old version of firmware is rather stable, so in the worst case where we are not able to completely debug the new firmware, we would make minor modifications on the old firmware.

Design Changes

No changes to our design at this point.

Schedule

We remain on schedule.

Sharon’s Status Report for 3/15/2025
Posted by : hsuanjul Sharon's Status Reports

Accomplishments

  • Received manufactured PCB: did basic power testings on the board to make sure there is no short circuit on the board and all pins are soldered on the correct pads. Pulled test points to high and verified basic function of the MCU.
  • Started testing the firmware: flashed the updated firmware to the board. Assisted Nadia with debugging the firmware.

Schedule Update

I will spend most of my time assisting Nadia with the firmware for the rest of the semester.

Plans for Next Week

Assist Nadia with firmware testing.

Sharon’s Status Report for 3/8/2025
Posted by : hsuanjul Sharon's Status Reports

Accomplishments

  • Last week was midterm week and everyone on the team were extremely busy. Therefore, we decided to take a break from the project.

Schedule Update

PCB verification part is a bit off track since we are still waiting for it to be manufactured. I will work on verification as soon as the board arrives after spring break.

Plans for Next Week

Assist Nadia with firmware testing. PCB verificationb

Sharon’s Status Report for 2/22/2025
Posted by : hsuanjul Sharon's Status Reports

Accomplishments

  • Wrapped up my part for a firmware update and handed it over to Nadia.
  • Made final adjustments on BOM and layout for PCB, and ordered through JLC. It is expected to ship next week. We are looking to receive it by the end of next week or at the start of the week after next.
  • Made adjustments on 3D-Model: put an additional hole for an LED signal on the wand body to align with the updated PCB for better usability.

Please check the project GitHub for updated details.

Schedule Update

PCB verification part is a bit off track since we are still waiting for it to be manufactured. As we wait for the PCB, we will focus more on the firmware side so that we will be able to have a working firmware once we get the customized PCB.

Plans for Next Week

Assist Nadia with firmware testing.

Sharon’s Status Report for 02/15/2025
Posted by : hsuanjul Sharon's Status Reports

Accomplishments

  • Continued update firmware, the updated firmware with HAL library is compilable right now:

IR Module Updates — checked the IR library for efficiency, and deleted redundant functions

Wand Module Adjustments — removed all modules except IR to discard the struct types that we no longer need. Noted that TIM2 configuration may be misaligned with the system frequency, potentially causing timing issues.

Deleted ADC & USART — Removed the ADC and USART modules entirelyand merged them into main.c.

Update memory allocation for CNN — Implemented a new weight_update mode to store constants in external flash rather than the microcontroller’s limited internal flash. Also wrote the corresponding script that updates weight.h. The static buffer in main.c was reduced from 1024 * 8 to 1024 * 7 to avoid a runtime overflow. Note that this change still needs verification through stress testing to confirm that the RAM usage is stabilized and no new overflow condition arises.

  • Updated PCB, connected with Professor Bain, and confirmed to use JLC for manufacturing. Still trying to connect with Quinn to get informed about the purchase procedure.

Please check the project GitHub for updated details.

Schedule Update

The firmware schedule remains on track. For the PCB manufacturing, I am slightly behind schedule. I’ll start going through the purchasing process as soon as I connect with Quinn next week.

Plans for Next Week

  • Confirm the RAM usage fix (reduced static buffer) is stable.
  • Test updated firmware on board and debug.
  • Get the first PCB version manufactured ASAP.