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28 Portable Bluetooth Music Player
Arpan Choudhury
Joseph Yang
Robert Conklin
William Zhang design_document1.pdf
# Portable Bluetooth Music Player

Arpan Choudhury arpanc2

Joseph Yang josephy2

Robert Conklin rmc2

## Problem :

Current music playback devices are increasing in size to meet the demand for larger and larger screen sizes. Along with this, the weight of these devices is rather large, as a result of using metals and glass to give users a 'premium feel,' and increasing battery size to maximize the charge life of the device. These factors combine to make good smart devices; however, they also lead to bulky/inconvenient device profiles for physical activity, especially activities like running.

## Solution Overview :

A clip-on wireless music player, capable of storing the user's music, and connecting to wireless headphones via Bluetooth while still still being lightweight and convenient to wear while exercising. The music player will use a Cortex-M series microcontroller to interface with a BLE module to communicate with the paired Bluetooth headset, read from flash memory to store and play back audio, and read user input from buttons on the device.
## Solution Components :

### MCU :

For this device, a versatile, low-power, and compact microcontroller is required, as the focus of the project is to design a lightweight, small profile music player. Due to the power-efficient design and low cost of the K32 L2 (K32L2B31VLH0A) MCU, this microcontroller appears to be the current best fit for the design, as it fits all the conditions listed above. Additionally, it has native USB 2.0 support hardware, simplifying the design process, and ensuring that the device will handle USB communication. Along with this, the K32 L2 has a sufficient amount of GPIO pins in addition to the required DMA and I2C connections to handle the flash memory and various peripherals, respectively.

### Bluetooth :

For connectivity to the Bluetooth headphones, a Bluetooth module is required to manage and handle the communication between the headphones and the MCU.

### Memory :

The music player should have enough space so that users can listen to music for the duration of an entire workout. We decided that 2 GB would be a reasonable size for this purpose (roughly 500 songs). While this may be less than the amount of space available on modern smartphones, we only need a few hours of storage capacity at max, and 2 GB is capable of holding significantly more than that.

### Interface :

To reduce weight, size, and cost of production, we decided to use a simple monochrome OLED display and button interface. We can limit pausing, playing, and track selection to to a single button, using double, or triple tapping to skip forward and skip backward respectively. Mapping these functions to the same button would simplify the design, allowing for less space to be used, while still having strong functionality. In addition, there would be power button, to turn on and off the device. Pairing the device could be accomplished using multiple held button presses,

### Battery :

We are planning on using a standard lithium-ion battery and charging system. This is due to the compact and high energy density of these systems, along with the variety of available systems.

### Display :

A small monochrome OLED display, interfacing with the MCU via I2C, allowing for pairing information to be displayed to the user when setting up the Bluetooth connection to a pair of wireless headphones.

## Criterion for Success :

A device capale of receiving and writing audio data to flash memory, and playing back audio from memory via a Bluetooth device. This includes meeting the memory/storage requirements in the design of the device, working user interface to control device, and having electronic components configured compactly enough to fit into a slim exterior profile.

Master Bus Processor

Clay Kaiser, Philip Macias, Richard Mannion

Master Bus Processor

Featured Project

General Description

We will design a Master Bus Processor (MBP) for music production in home studios. The MBP will use a hybrid analog/digital approach to provide both the desirable non-linearities of analog processing and the flexibility of digital control. Our design will be less costly than other audio bus processors so that it is more accessible to our target market of home studio owners. The MBP will be unique in its low cost as well as in its incorporation of a digital hardware control system. This allows for more flexibility and more intuitive controls when compared to other products on the market.

Design Proposal

Our design would contain a core functionality with scalability in added functionality. It would be designed to fit in a 2U rack mount enclosure with distinct boards for digital and analog circuits to allow for easier unit testings and account for digital/analog interference.

The audio processing signal chain would be composed of analog processing 'blocks’--like steps in the signal chain.

The basic analog blocks we would integrate are:

Compressor/limiter modes

EQ with shelf/bell modes

Saturation with symmetrical/asymmetrical modes

Each block’s multiple modes would be controlled by a digital circuit to allow for intuitive mode selection.

The digital circuit will be responsible for:

Mode selection

Analog block sequence

DSP feedback and monitoring of each analog block (REACH GOAL)

The digital circuit will entail a series of buttons to allow the user to easily select which analog block to control and another button to allow the user to scroll between different modes and presets. Another button will allow the user to control sequence of the analog blocks. An LCD display will be used to give the user feedback of the current state of the system when scrolling and selecting particular modes.

Reach Goals

added DSP functionality such as monitoring of the analog functions

Replace Arduino boards for DSP with custom digital control boards using ATmega328 microcontrollers (same as arduino board)

Rack mounted enclosure/marketable design

System Verification

We will qualify the success of the project by how closely its processing performance matches the design intent. Since audio 'quality’ can be highly subjective, we will rely on objective metrics such as Gain Reduction (GR [dB]), Total Harmonic Distortion (THD [%]), and Noise [V] to qualify the analog processing blocks. The digital controls will be qualified by their ability to actuate the correct analog blocks consistently without causing disruptions to the signal chain or interference. Additionally, the hardware user interface will be qualified by ease of use and intuitiveness.

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