ESP32 on QEMU

This guide provides step-by-step instructions to set up and run an ESP-IDF project for ESP32 using QEMU (an emulator for ESP32). You can develop and test ESP32 applications without actual hardware.

Features

• Complete ESP32 emulation.
• BMP280 emulation.

Setup Instructions

Prerequisites

• ESP-IDF installed (export.sh sourced)
• QEMU installed (for emulation)

Steps to Build and Run

1. Create Project (If Not Done)

idf.py create-project esp32_counter
cd esp32_counter

2. Write Main Code

Modify main/esp32_counter.c and add the counter logic.

3. Create Project

Build the Project

idf.py build

4. Run on Hardware

idf.py flash
idf.py monitor

5. Run on QEMU

Merge binaries:

esptool.py --chip esp32 merge_bin -o flash_image.bin --flash_mode dio --flash_size 4MB \
    0x1000 build/bootloader/bootloader.bin \
    0x8000 build/partition_table/partition-table.bin \
    0x10000 build/esp32_counter.bin

Run in QEMU:

qemu-system-xtensa -nographic -machine esp32 \
    -drive file=flash_image.bin,if=mtd,format=raw

In case your flash_image.bin is less than 4.0MB you will have to run:

truncate -s 4M flash_image.bin

verify the size of flash_image.bin using:

ls -lh flash_image.bin

Then re-run using QEMU

6. Print data on serial port? (hack)

Modify QEMU command - Update your QEMU command to expose the serial port via TCP:

qemu-system-xtensa -nographic -machine esp32 \
    -drive file=flash_image.bin,if=mtd,format=raw \
    -serial tcp::1234,server,nowait

This makes QEMU listen on TCP port 1234 for serial connections.

7. Read on serial port using JS

Create a Node.js script to read from the TCP port:

const net = require('net');

// Connect to QEMU's serial port over TCP
const client = net.createConnection({ port: 1234 }, () => {
    console.log('Connected to ESP32 emulator');
});

// Handle incoming data
client.on('data', (data) => {
    console.log(data.toString());
});

client.on('error', (err) => {
    console.error('Connection error:', err);
});

client.on('close', () => {
    console.log('Connection closed');
});