T3-S3 MVSR Quick Start

Required Libraries

Library	Version	Source
RadioLib	Latest	GitHub
ESP-IDF I2S	Built-in	ESP32 Arduino Core

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Arduino

PlatformIO (Recommended)

1. Install VS Code with the PlatformIO IDE extension
2. Clone the repository:

   git clone https://github.com/Xinyuan-LilyGO/T3-S3-MVSRBoard.git

3. Open the project and select the appropriate environment in platformio.ini
4. Click ✓ to build, connect via USB-C, then click → to upload

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Arduino IDE

Board Settings

Setting	Value
Board	ESP32S3 Dev Module
Upload Speed	921600
USB Mode	Hardware CDC and JTAG
USB CDC On Boot	Enabled
CPU Frequency	240 MHz (WiFi)
Flash Mode	QIO 80 MHz
Flash Size	16MB (128Mb)
Partition Scheme	16M Flash (3MB APP/9.9MB FATFS)
PSRAM	OPI PSRAM

Steps

1. Install Arduino IDE and add ESP32 board support: https://espressif.github.io/arduino-esp32/package_esp32_index.json
2. Clone the T3-S3-MVSRBoard repo and open an example sketch
3. Select the board settings above and click Upload

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Peripheral Examples

Speaker (MAX98357A I2S)

#include <driver/i2s.h>

// MAX98357A: BCLK=42, LRCK=41, DOUT=40, SD=39
#define I2S_BCLK  42
#define I2S_LRCK  41
#define I2S_DOUT  40
#define I2S_SD    39

void setup() {
  // Enable amplifier
  pinMode(I2S_SD, OUTPUT);
  digitalWrite(I2S_SD, HIGH);

  i2s_config_t cfg = {
    .mode = (i2s_mode_t)(I2S_MODE_MASTER | I2S_MODE_TX),
    .sample_rate = 16000,
    .bits_per_sample = I2S_BITS_PER_SAMPLE_16BIT,
    .channel_format = I2S_CHANNEL_FMT_RIGHT_LEFT,
    .communication_format = I2S_COMM_FORMAT_STAND_I2S,
    .intr_alloc_flags = ESP_INTR_FLAG_LEVEL1,
    .dma_buf_count = 8,
    .dma_buf_len = 64,
  };
  i2s_pin_config_t pins = {
    .bck_io_num = I2S_BCLK,
    .ws_io_num  = I2S_LRCK,
    .data_out_num = I2S_DOUT,
    .data_in_num = I2S_PIN_NO_CHANGE,
  };
  i2s_driver_install(I2S_NUM_0, &cfg, 0, NULL);
  i2s_set_pin(I2S_NUM_0, &pins);
}

Microphone (V1.0: MSM261S I2S / V1.1: MP34DT05 PDM)

// V1.0 — I2S microphone
#include <driver/i2s.h>

#define MIC_SCK  46
#define MIC_WS   45
#define MIC_SD   47

void setup() {
  Serial.begin(115200);
  i2s_config_t cfg = {
    .mode = (i2s_mode_t)(I2S_MODE_MASTER | I2S_MODE_RX),
    .sample_rate = 16000,
    .bits_per_sample = I2S_BITS_PER_SAMPLE_32BIT,
    .channel_format = I2S_CHANNEL_FMT_ONLY_LEFT,
    .communication_format = I2S_COMM_FORMAT_STAND_I2S,
    .intr_alloc_flags = ESP_INTR_FLAG_LEVEL1,
    .dma_buf_count = 8,
    .dma_buf_len = 64,
  };
  i2s_pin_config_t pins = {
    .bck_io_num = MIC_SCK,
    .ws_io_num  = MIC_WS,
    .data_out_num = I2S_PIN_NO_CHANGE,
    .data_in_num = MIC_SD,
  };
  i2s_driver_install(I2S_NUM_1, &cfg, 0, NULL);
  i2s_set_pin(I2S_NUM_1, &pins);
}

void loop() {
  int32_t sample;
  size_t bytes_read;
  i2s_read(I2S_NUM_1, &sample, sizeof(sample), &bytes_read, portMAX_DELAY);
  Serial.println(sample >> 14);
}

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Notes

• Expansion board: The MVSR is a baseboard that stacks onto the T3-S3 V1.2 main board — it is not standalone
• Speaker: MAX98357A I2S amplifier (9 dB gain); use the ESP32 I2S peripheral to drive audio output
• Microphone: V1.0 uses MSM261S4030H0R (I2S); V1.1 changed to MP34DT05-A (PDM) — check your hardware revision before selecting the driver
• RTC: PCF85063ATL on I2C for timestamped logging
• Deep sleep: Current draw is 2.77 µA in deep sleep — suitable for battery-powered deployments

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FAQ

Q: No audio output? A: Verify the I2S pins match the MVSR schematic and that MAX98357A SD pin is driven HIGH (not floating) to enable the amplifier.

Q: Microphone not working? A: Check your hardware revision — V1.0 uses I2S mic driver, V1.1 uses PDM mic driver. Using the wrong driver will yield silence.