Lab 5: Digital Music Player with TLV5616 DAC and LM4890 Audio Amplifier

Team Size

2

Project Overview

This lab demonstrates how to generate analog audio signals from a microcontroller using a 12-bit TLV5616 DAC and an LM4890 audio amplifier. The system stores music as a data structure, sends digital values to the DAC over SSI1, and drives an 8Ω speaker.

Key features:

• High-quality analog waveform generation from digital data
• Modular software with separate drivers for DAC, switches, and music playback
• Timer interrupts for precise waveform timing
• Audio output through a speaker with configurable gain

---

Hardware

• Microcontroller: EK-TM4C123GXL
• DAC: TLV5616C 12-bit (single, SSI interface)
• Audio Amplifier: LM4890M
• Voltage Reference: LM4041CILPR
• Speaker: 8Ω
• Passive components: Resistors, capacitors as required

TLV5616C SSI Pin Connections

• SSIClk (SCLK) → PD0
• SSIFss (FS) → PD1
• SSITx (DIN) → PD3

The SSI module is configured to match the TLV5616 timing: SPO=1, SPH=0, SCR=0, CPSDVSR=8, DSS=16-bit.

---

Software Overview

• DAC driver: DAC.h / DAC.c
  • DAC_Init(uint16_t data) – initializes SSI1 and sets initial DAC output
  • DAC_Out(uint16_t code) – sends a 12-bit value to the DAC
• Switch driver: Switch.h / Switch.c for user input
• Music player module: Music.h / Music.c
  • Stores song as a structured array of notes and durations
  • Handles playback using timer interrupts

---

Project Goals

• Understand DACs and voltage references
• Create SSI communication with correct timing for TLV5616
• Design and implement modular software for music playback
• Drive a speaker with an audio amplifier to produce high-quality sound

---

Procedure

1. Write low-level drivers

   • Implement DAC initialization and data transmission over SSI1
   • Implement switch interface for controlling playback

2. Design music data structure

   • Store notes, durations, and optional rests or envelopes
   • Implement Music_Play() to stream data to DAC using interrupts

3. Assemble DAC and voltage reference

   • Connect TLV5616C to TM4C123GXL using SSI1 pins
   • Build voltage reference circuit using LM4041CILPR for stable DAC output

4. Build audio amplifier

   • Solder LM4890 to a breakout board
   • Connect amplifier output to the 8Ω speaker

5. Debug and test

   • Verify DAC output matches expected values
   • Listen to the music playback and tune amplifier gain for linearity
   • Optional: Enclose speaker to enhance sound quality

---

References

• TLV5616C Datasheet
• LM4890 Datasheet
• LM4041 Voltage Reference Datasheet
• TM4C123GXL Periodic Timer and SSI example projects

---

Notes

• Only the TLV5616C DAC and LM4041CILPR voltage reference are used in this project.
• Sound quality is prioritized over loudness.
• Factors affecting quality:
  • DAC precision and linearity
  • Amplifier gain and frequency response
  • DAC update rate and interrupt jitter
  • Complexity of the stored music data