Build a Car With Your Kid
The car remote
For a car with an HM-10. Use Chrome on Android or Bluefy on iPhone. Tap Connect, choose your module (usually HMSoft), then hold a button to drive.
Checking whether this browser can use Bluetooth…
What it sends
Every button sends one letter to the car, the same letters you can type in the Serial Monitor. Holding a drive button sends its letter once; letting go sends S. The car answers every letter with a line like Car heard: F, which appears under the buttons: that is the round trip, phone to car and back.
- F
- Forward, while you hold the button
- B
- Back, with a beep
- L
- Spin left
- R
- Spin right
- S
- Stop — sent when you let go, and by the Stop button
- 1–9
- Speed, 1 the slowest; the car keeps moving at the new speed
- V
- Horn, until the next letter
- X
- Happy Birthday (the remote sends S first)
Common questions
- Why does the remote not find my car?
- On Android, turn on Location and give Chrome the Nearby devices permission, then tap Connect again. Make sure the car is switched on and the module’s light is blinking. Do not pair the HM-10 in the phone’s Bluetooth settings; if you already did, forget it there.
- Does it work on an iPhone?
- Not in Safari or Chrome: iPhone browsers have no Web Bluetooth. Install the free Bluefy browser and open the same address in it.
- Does it work with an HC-06?
- No. The HC-06 is Classic Bluetooth, which web pages cannot reach. Use the Serial Bluetooth Terminal app on Android, as Chapter 10 of the book shows.
- What happens if the phone disconnects while the car is moving?
- The car keeps doing the last letter it heard, because its sketch has no timeout. Switch the battery holder off. The remote sends S whenever you let go of a button, switch apps or turn the screen off, so this only happens when the connection itself drops.