WALKIE TALKIE
By Zach Berthillier, Akshay Shivkumar, Alex Wong, and Hailey Kim
Embedded Files
about:
tldr:
we made walkie-talkies! they enable low-latency, long-range, two-way wireless voice communication with positional awareness. we designed custom PCBs w/ embedded hardware and RF (Real Freakincoolstuff) š¼
description:
our walkie-talkies capture analog voice input through an onboard MEMS microphone, digitize and package the data using an STM32L4 MCU, and transmit wirelessly over a LoRa RF link. the received audio stream is decoded and amplified for playback through a speaker, enabling push-to-talk communication between units.
in addition to voice transmission and reception, the system integrates GPS and IMU sensors to provide real-time positional data, which is displayed on an onboard screen alongside signal strength and system status. the device is powered by a rechargeable LiPo battery with efficient onboard regulation, making it suitable for portable, low-power operation while maintaining clear audio quality and robust wireless performance
problem statement:
problem statement:
motivation:
its cool š
features:
STM32 MCU for centralized control (audio, RF, sensors) with SWD debugging
Digital audio chain: microphone input, conditioning, digitization, packetization, reconstruction, and speaker amplification
LoRa long-range wireless module with external antenna
GPS module for real-time location data
IMU via IĀ²C for motion/orientation sensing
Integrated power management: LiPo battery, buck regulator, and LDO rails
User interface: onboard display (signal strength, GPS, status), push-to-talk button
schematic:
layout:
4-layer stackup (signal-gnd-pwr-signal)
Switching regulator isolation
Mounting holes for 3D-printed case
3.0 x 3.0 in form factor
front shot
back shot
3D viewer:
front shot
back shot
bill of materials:
cost per unit: $89.5 ($88.1 for components, $1.4 per board)
bring-up:
unsoldered boards
used a stencil for SMT components (ignore the handsome guy)
we baked the boards in the reflow oven until they were golden brown
we hand-soldered the through-holes
mechanical design:
Designed on Onshape
3D printed w/ PLA
Tolerances tuned for tight fit
Openings for mic, antenna, battery, speaker
case!š¼
pcb inside case š
final product!
100+ (wo)man-hours spent
200+ traces routed
122 components soldered
60,000 bits transmitted + received wirelessly
But we did it!
audio clip: https://drive.google.com/file/d/1wxUHknRIKa1Sa27G1J9l0vAhShdWo36F/view?usp=sharing
Meet Laura and Mike!
the team:
akshay shivkumar
2nd year EECS
like minion
alex wong
3rd semester EECS
car
zach berthillier
16-months-in EECS
franse
hailey kim
4.205*10^7sĀ EECS experience
niche apple
"r u workin hard or hardly workin???" - wise man
Poll:
workin hard: å|
hardly workin: åååååå
Page updated
Report abuse