What is a DAC?

A DAC (Digital-to-Analog Converter) converts a number in your code into a real voltage on a pin. Write 2048 and the pin outputs ~1.65V. Write 4095 and you get ~3.3V. Write 0 and you get 0V. It’s the opposite of an ADC, which reads voltages and turns them into numbers.

Why This Matters for Your Projects

DACs are used for generating audio signals, creating precise reference voltages, and producing smooth waveforms. Your phone uses a DAC every time it plays audio through a speaker.

But here’s the thing: the ESP32-S3 does not have a built-in DAC. The original ESP32 had two 8-bit DAC channels, but Espressif removed them from the S3. So if you need true analog output on your tinyCore, you have three options — and for most projects, one of them will work perfectly.

Option 1: PWM (Good Enough for Most Things)

The ESP32-S3 has 8 PWM channels (called LEDC) that rapidly flip a pin between 3.3V and 0V. By controlling what percentage of time the pin stays HIGH (the duty cycle), you create an average voltage. Set 50% duty and the average output is ~1.65V.

This isn’t true analog — it’s a fast square wave. But for many tasks, it works great:

• LED dimming — your eyes can’t see the switching
• Motor speed control — the motor’s inertia smooths it out
• Servo positioning — servos read the pulse width, not voltage
• Fan speed — same as motors

Where PWM falls short: audio output, precision voltage references, and circuits that need a steady, clean voltage. The rapid switching creates noise that analog-sensitive circuits don’t like.

Rule of thumb: if what you’re controlling has physical inertia (mechanical, thermal, or visual), PWM works. If a downstream circuit cares about the actual instantaneous voltage, you need a real DAC.

See What is PWM? for a deep dive.

Option 2: I2S for Audio

For audio output specifically, the ESP32-S3 has 2 I2S peripherals designed for streaming digital audio to external amplifier or DAC chips. Pair it with a MAX98357A (I2S amplifier, drives speakers directly) or a PCM5102A (stereo I2S DAC for higher-quality audio) and you get proper audio playback — 16/24-bit resolution at 44.1 or 48 kHz.

The tinySpeak HAT uses this approach. See What is I2S? for details.

Option 3: External DAC Chip for Precise Voltage

For general-purpose analog output, you can plug a small external DAC into the tinyCore’s QWIIC/I2C port. The most popular choice:

MCP4725 (I2C, 12-bit)

The beginner favorite. One output channel, 4,096 voltage steps, dead-simple I2C interface. Available as a QWIIC/STEMMA breakout — just plug in a cable, no breadboard needed.

#include <Wire.h>
#include <Adafruit_MCP4725.h>

Adafruit_MCP4725 dac;

void setup() {
  pinMode(6, OUTPUT);
  digitalWrite(6, HIGH);    // power on I2C bus
  Wire.begin(3, 4);         // tinyCore I2C pins
  dac.begin(0x62);           // default address on Adafruit boards
}

void loop() {
  dac.setVoltage(2048, false);  // ~1.65V (half of 3.3V)
  delay(1000);
  dac.setVoltage(4095, false);  // ~3.3V (full scale)
  delay(1000);
  dac.setVoltage(0, false);     // 0V
  delay(1000);
}

The setVoltage() function takes a value from 0 to 4095. Output voltage = (value / 4096) × 3.3V. The second parameter (false) means “don’t save to EEPROM” — keep it false for normal use.

Tip

If the default I2C address doesn’t work, try 0x60 — different MCP4725 breakouts use different defaults. Run an I2C scanner if you’re stuck.

Install the library: Sketch → Include Library → Manage Libraries → search “Adafruit MCP4725” → Install.

Other External DAC Options

Chip	Interface	Resolution	Best For
MCP4725	I2C	12-bit (4,096 steps)	General purpose, easy setup
MCP4921	SPI	12-bit	Faster updates, waveform generation
PCM5102A	I2S	32-bit stereo	High-quality audio playback

Quick Reference: PWM vs External DAC

	PWM (built-in)	External DAC (MCP4725)
Cost	Free	~$5 for breakout
Good for	LEDs, motors, fans, servos	Precision voltage, waveforms, analog circuits
Output	Pulsed square wave	Clean, steady analog voltage
Resolution	Up to 14-bit	12-bit
Setup	One line of code	I2C library + QWIIC cable

Learn More

• What is PWM? — the most common DAC alternative on the ESP32-S3
• What is I2S? — audio output through external DAC/amplifier chips
• What is an ADC? — the opposite: reading voltages into numbers
• What is I2C? — the protocol used by external DAC breakouts