L293D Motor Driver IC

(Datasheet) and product at RS Components

The L293D has four outputs that can sink 600mA, each of which can pull up to a voltage as well as down to 0v. This makes it ideal for driving motors in forwards and reverse, as each side of the motor can be connected to an output. Outputting 0 and 1 will make it turn one way, and outputting 1 and 0 will make it turn the other.

It's available in a few different types, but we're interested in:

• 16 pin DIP package : This is great for BreadBoard or making your own PCBs
• 20 pin SOIC: This can be soldered directly onto the Espruino board

Connections

To use, simply connect as follows:

Pin	Function	Connect To
VS	Supply Voltage	Battery Positive, or Bat on the Espruino
VSS	Logic Supply Voltage	Bat on the Espruino
GND	Ground	Ground on Espruino and Battery
ENABLE 1/2	Enable Outputs	Bat on the Espruino (if you always want them on)
INPUT 1/2/3/4	Logic Inputs	Any logic pin on the Espruino board
OUTPUT 1/2/3/4	Power Outputs	Your Motors/etc

If you're soldering the 20 pin SOIC onto the board, we'd suggest that you connect as follows:

L293D	Espruino
1 - ENABLE 1	BAT
2 - INPUT 1	A3
3 - OUTPUT 1	Connect to pin strip
4 - GND	GND
5 - GND	GND
6 - GND	GND
7 - GND	GND
8 - OUTPUT 2	Connect to pin strip
9 - INPUT 2	A2
10 - VS	BAT
11 - ENABLE 2	BAT
12 - INPUT 3	B10
13 - OUTPUT 3	Connect to pin strip
14 - GND	GND
15 - GND	GND
16 - GND	GND
17 - GND	GND
18 - OUTPUT 4	Connect to pin strip
19 - INPUT 4	B11
20 - VSS	BAT

That way, every output can have PWM.

Software

To use this, you just need to send a 1 or a 0 out of Espruino. If you've wired up as suggested, the simplest code to turn output 1 on is digitalWrite(A3,1).

However with multiple outputs it's often easier to reference them by number:

var outputs = [A3,A2,B10,B11];

digitalWrite(outputs[0],1); // output 1
digitalWrite(outputs[3],1); // output 4

You can also use analogWrite (using PWM) to turn an output on for half of the time:

var outputs = [A3,A2,B10,B11];

analogWrite(outputs[1], 0.5, { freq: 100 }); // Turn output 2 on, 50% of the time, at 100 Hz

Using