Build a Car With Your Kid · Chapter 8
Stage B2: the caps off, the six signal wires on
The video
The video of the caps coming off and the six wires going on isn’t filmed yet. It’s on its way, and it will go on this page: the QR in your book stays the same.
Until then, here are those steps as Chapter 8 prints them. The caps come off first: with a cap on, the motor driver ignores the board’s speed wire and every speed is the same. Steps B21 to B28 (the buzzer and the horn test) are in the chapter between these two.
Steps B18 to B35
Warning
All power off before you start: the USB cable unplugged and the battery switch off. The cells are still out.
Pull the cap off the ENA pins, straight up, with your fingers or small pliers. Put it in a bag so it doesn't get lost.
Pull the cap off the ENB pins the same way. Leave the cap near the power screws where it is.
Check: no cap on ENA or ENB. Each cap covered two pins: the ENA (or ENB) pin, in the row with IN1 to IN4, and a 5V pin behind it. The speed wire will go on the pin in the row.
The six signal wires
Now the six wires. Each is a male-to-female jumper. The female end, the one with a hole, pushes onto the motor driver's pin. The male end, the one with a pin, goes into the board's socket.
Warning
All power off: the USB cable unplugged and the battery switch off.
ENA on the motor driver to pin 5 on the board.
ENB to pin 6.
IN1 to pin 12.
IN2 to pin 11.
IN3 to pin 10.
IN4 to pin 9.
| Motor driver pin | Board pin | Does |
|---|---|---|
| ENA | 5 | Left side's speed |
| ENB | 6 | Right side's speed |
| IN1 | 12 | Left side's direction |
| IN2 | 11 | Left side's direction |
| IN3 | 10 | Right side's direction |
| IN4 | 9 | Right side's direction |
Check all six against the table in Chapter 8, one at a time, reading each pair aloud: "ENA, pin 5." The child points to both ends of the wire.
Where to go from here
Stage B is tested in Chapter 9: the wheels test →Why a cap left on makes every speed the same: the PWM lab →The motor driver: every pin and the wiring →If the car doesn’t move: every symptom, its stage and its fix →The free book: Build a Car With Your Kid →