L298n (L298N v0.1.0)

Elixir library for controlling L298N dual H-bridge motor driver.

The L298N is a popular dual H-bridge motor driver IC that can control up to 2 DC motors or 1 stepper motor. This library provides a high-level Elixir interface for controlling motors through GPIO pins using the Pigpiox library.

Features

Control up to 2 DC motors independently
PWM speed control (0-100%)
Direction control (forward/backward)
Safe motor stopping
GenServer-based process for state management

Hardware Setup

Connect your L298N module to your Raspberry Pi as follows:

L298N Pin	Raspberry Pi GPIO	Function
IN1	GPIO pin	Motor A direction control
IN2	GPIO pin	Motor A direction control
ENA	PWM GPIO pin	Motor A speed control
IN3	GPIO pin	Motor B direction control
IN4	GPIO pin	Motor B direction control
ENB	PWM GPIO pin	Motor B speed control

Usage

First, start the driver with your pin configuration:

{:ok, pid} = L298n.start_link([
  motor_a: %{in1: 18, in2: 19, en: 12},
  motor_b: %{in1: 20, in2: 21, en: 13}
])

Then control your motors:

# Move both motors forward at 50% speed
L298n.set_motors(50, 50)

# Turn left (motor A forward, motor B backward)
L298n.set_motors(30, -30)

# Stop all motors
L298n.stop_all()

Motor Speed Values

Motor speed is specified as a percentage from -100 to 100:

Positive values: Forward direction
Negative values: Backward direction
0: Stop
±100: Full speed

Summary

Functions

get_motor_speeds()

Gets the current motor speeds.

set_motor_a(percent)

Sets the speed for motor A only.

set_motor_b(percent)

Sets the speed for motor B only.

set_motors(motor_a_percent, motor_b_percent)

Sets the speed and direction for both motors.

start_link(opts \\ [])

Starts the L298N driver process.

stop_all()

Stops all motors immediately.

Functions

get_motor_speeds()

@spec get_motor_speeds() :: %{motor_a: integer(), motor_b: integer()}

Gets the current motor speeds.

Returns a map with the current speed settings for both motors.

Examples

L298n.get_motor_speeds()
#=> %{motor_a: 50, motor_b: -30}

set_motor_a(percent)

@spec set_motor_a(integer()) :: :ok

Sets the speed for motor A only.

Parameters

percent - Speed for motor A (-100 to 100)

Examples

L298n.set_motor_a(75)   # Motor A forward at 75%
L298n.set_motor_a(-50)  # Motor A backward at 50%
L298n.set_motor_a(0)    # Stop motor A

set_motor_b(percent)

@spec set_motor_b(integer()) :: :ok

Sets the speed for motor B only.

Parameters

percent - Speed for motor B (-100 to 100)

Examples

L298n.set_motor_b(75)   # Motor B forward at 75%
L298n.set_motor_b(-50)  # Motor B backward at 50%
L298n.set_motor_b(0)    # Stop motor B

set_motors(motor_a_percent, motor_b_percent)

@spec set_motors(integer(), integer()) :: :ok

Sets the speed and direction for both motors.

Parameters

motor_a_percent - Speed for motor A (-100 to 100)
motor_b_percent - Speed for motor B (-100 to 100)

Speed values:

Positive: Forward direction
Negative: Backward direction
0: Stop

Examples

# Both motors forward at 50% speed
L298n.set_motors(50, 50)

# Motor A forward, Motor B backward (turn)
L298n.set_motors(30, -30)

# Stop both motors
L298n.set_motors(0, 0)

start_link(opts \\ [])

@spec start_link(keyword()) :: GenServer.on_start()

Starts the L298N driver process.

Parameters

opts - Keyword list with motor pin configurations

Options

:motor_a - Map with keys :in1, :in2, :en for motor A pins
:motor_b - Map with keys :in1, :in2, :en for motor B pins
:name - Process name (optional, defaults to L298n.Driver)

Examples

# Start with both motors configured
{:ok, pid} = L298n.start_link([
  motor_a: %{in1: 18, in2: 19, en: 12},
  motor_b: %{in1: 20, in2: 21, en: 13}
])

# Start with only motor A
{:ok, pid} = L298n.start_link([
  motor_a: %{in1: 18, in2: 19, en: 12}
])

stop_all()

@spec stop_all() :: :ok

Stops all motors immediately.

This is equivalent to calling set_motors(0, 0).

Examples

L298n.stop_all()