ESP32 OS-Based Prototype with TFT Display, SD Card, and Audio Output

📌 Overview

This project is a prototype for building an operating system-like interface on an ESP32, integrating a TFT display, SD card, and audio output using a MAX98357A DAC. Key design decisions prioritize stable performance and hardware compatibility.

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⚠️ Notes

• Power Management
  To avoid flickering of the TFT display when audio is active:
  - Use separate VINs for the TFT Display and MAX98357A.
  The flickering in tft display during audio output was due to me powering the board with through a type-C connection. Using a normal USB port is fine.

• SD Card Compatibility

  • SD cards of 32GB or more often fail to work reliably with the SD.h library.
  • ✅ Recommended: SanDisk Ultra 16GB SDHC Memory Card, 80MB/s — tested and working.

• Playing different WAV files

  • I can only play wav files up to 10 MB reliably.
  • Need to design a protocol to group similar audio files.
  • FFMPEG command: ffmpeg -y -i 505aud.mp3 -ar 22050 -ac 1 -sample_fmt s16 -t 200 5052.wav to bring down the 505 wav file to 10MB.

• Uploading to flash issue

  • Cut power to peripherals because the pins being used by the hspi line for SD card are needed to flash the chip. "SPI flash".

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📟 Pinout Summary

🔹 TFT Display (VSPI - Default SPI)

Signal	ESP32 Pin	Description
MISO	GPIO 19	SPI Master In Slave Out
MOSI	GPIO 23	SPI Master Out Slave In
SCLK	GPIO 18	SPI Clock
TFT_CS	GPIO 15	TFT Chip Select
TFT_DC	GPIO 2	TFT Data/Command Select
TFT_RST	GPIO 4	TFT Reset
Power	3.3V	VIN for TFT

🔹 SD Card (HSPI - Custom SPI)

Signal	ESP32 Pin	Description
MISO	GPIO 12	HSPI Master In Slave Out
MOSI	GPIO 4	HSPI Master Out Slave In
SCLK	GPIO 14	HSPI Clock
SD_CS	GPIO 5	SD Card Chip Select
Power	3.3V	VIN for SD Card

Note:

• SD card and TFT are now on separate SPI buses (HSPI for SD, VSPI for TFT). This avoids bus contention and allows concurrent use.

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🔊 Audio Output (MAX98357A DAC, I2S)

Signal	ESP32 Pin	Description
Power	3.3V	VIN for MAX98357A
BCLK	GPIO 27	I2S Bit Clock
LRC (WS)	GPIO 25	I2S Left/Right Clock
DIN	GPIO 26	I2S Digital Audio Input

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✅ To Do / Improvements

• Optimize display and audio concurrency.
• Explore FAT32 compatibility for larger SD cards using SdFat or ESP32SPISlave libraries.
• Implement low-power modes and voltage regulation monitoring.

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🛠️ Recommended Hardware

• ESP32 DevKit v1
• TFT Display (SPI, 2.4"–2.8")
• MAX98357A I2S DAC
• SanDisk Ultra 16GB SDHC Card
• External 5V Power Supply (for stable VIN separation)

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🔗 License

This prototype is open-source and intended for learning and prototyping use. Feel free to adapt and extend it.