Build guide
Upload and drive the Arduino Bluetooth car
Steps 4 to 6 of the Arduino Bluetooth car build guide: upload the sketch, drive the car from your phone, and share what you built. Steps 1 to 3, the parts, the wiring and the code, are on the guide, along with all six steps at a glance.
What you end up with: a four-wheel car you assembled from parts, driven from a phone over Bluetooth, with a horn and a reversing beep. No prior electronics, and no soldering anywhere in it.
Step 4 — Upload the sketch to the Uno
The sketch is a download, not something you type. Get it from the code page, or straight as a zip archive.
You need two things on the laptop: the Arduino Create web editor, and the plugin that lets a web page talk to a USB port. The editor will walk you through installing the plugin the first time. Then it is Sketchbook > Import, pick the zip, choose your board and port, and press Upload. Budget about twenty minutes. This is the step where an adult should be holding the laptop: not because it is dangerous, but because it means installing software and clicking through dialogs.
Unplug the two Bluetooth data wires before you upload. The HC-06 sits on pins 0 and 1, and those pins are the serial port the USB cable programs the board over. Leave the module connected and it talks over the top of the upload, which fails with an avrdude error that explains nothing at all.
This is the single most common way this build stalls, and nothing about it looks like a radio problem — people buy a new cable and reinstall drivers instead. Pull TXD and RXD, upload, plug them back in. Full explanation in Arduino will not upload with Bluetooth connected.
Newer wiring skips this step. The 2021 car and its sketch use pins 0 and 1, so the unplugging applies to them. Make It Connect puts the module on pins 2 and 3 through SoftwareSerial instead, which leaves 0 and 1 to the USB cable and removes the step entirely. It needs a sketch written for those pins, such as bluetooth-car.ino on the code page, not just moved wires.
On Windows the plugin is the Arduino Create Agent, and it has a few more dialogs than the other platforms. There is a screen-by-screen walkthrough in Uploading the car sketch on Windows.
Step 5 — Drive it from an Android phone
Classic Bluetooth SPP — which is what an HC-05 and an HC-06 speak — is invisible to iOS at the operating-system level. No app fixes it, no library fixes it, and no wiring change fixes it. You need a BLE module: a genuine HM-10, or an ESP32. And Web Bluetooth is not the escape hatch — it is not in Safari, any version.
First pair the phone with the module in the phone’s own Bluetooth settings, like any other device. The PIN is 1234, or 0000 on some boards; the pairing-code article has the rest.
The controller is a free app: search the Play Store for Arduino Bluetooth RC Car.
Open it, go into its settings, and pick your car from the list of paired devices. It shows up as HC-06.
Then drive it.
Worth knowing: under Option Menu > Settings the app shows the character it sends for each button. Those single letters are exactly what the sketch in step 3 switches on — so if you want a button to do something else, that is where the two ends meet.
Step 6 — Share what you built
Film it running and show it to someone. The Troniction Facebook group is where other people post theirs, or send it to me — I would rather see a car that works than get another email asking whether the guide is any good.
About the parts links
Some links on the parts list earn me a commission, and each one says so on the line. The rest earn nothing. Buy wherever is cheapest or closest — none of this build is specific to one shop.
The three parts worth understanding
You can build the car without reading these, but the point of the guide is that you finish knowing what you made: the Arduino Uno makes the decisions, the L298N motor driver does the pushing, and the HC-06 listens to your phone.
Stuck on something the guide does not cover? Tell me — if a step is unclear it is my problem, not yours, and it gets fixed for everyone.
Build it. Understand it.
Get the complete illustrated guide and start your first car — free.