關於L293D馬達驅動模板

L293D馬達驅動板

The shield contains two L293D motor drivers and one 74HC595 shift register. The shift register expands 3 pins of the Arduino to 8 pins to control the direction for the motor drivers. The output enable of the L293D is directly connected to PWM outputs of the Arduino.

The Motor Shield is able to drive 2 servo motors, and has 8 half-bridge outputs for 2 stepper motors or 4 full H-bridge motor outputs or 8 half-bridge drivers, or a combination.

模組板規格

• 2 connections for 5V 'hobby' servos connected to the Arduino's high-resolution dedicated timer - no jitter!
• 4 H-Bridges: L293D chipset provides 0.6A per bridge (1.2A peak) with thermal shutdown protection, internal kickback protection diodes. Can run motors on 4.5VDC to 25VDC.
• Up to 4 bi-directional DC motors with individual 8-bit speed selection (so, about 0.5% resolution)
• Up to 2 stepper motors (unipolar or bipolar) with single coil, double coil or interleaved stepping.
• Pull down resistors keep motors disabled during power-up
• Big terminal block connectors to easily hook up wires (18-26AWG) and power
• Arduino reset button brought up top
• 2-pin terminal block and jumper to connect external power, for separate logic/motor supplies
• Tested compatible with Arduino Mega 1280 & 2560, Diecimila, Duemilanove, and UNO
• Download the easy-to-use Arduino software library, check out the examples and you're ready to go!

http://www.kidmakers.org/-for-the-galileo/

Motor shield Motor電源與Arduino Vin 關係

L293D 線路

L293D 控制原理

L293D 電路產生一個不同電流流向使得Motor 有不同的轉動方向:

1. Vcc1/Vss--> 提供L293D chip的電源 5V
2. Vcc2/Vs --> 提供馬達電源 (max 36V); 從Arduino Vin 接入 (PWR jumper接上)或是motor shield的EXT_PWR接入 (PWR jumper要移除)
3. Enable1,2 及Enable3,4是致能訊號, 可以直接Vcc1; 也可以接到PWM訊號，給Enable1,2, 不同duty cycle，即提供馬達不同的功率, 使得馬達有不同轉速。Enable1,2接上Vcc1, 即duty cycle為100%,此為全速運轉
4. Output1及Output2接DC Motor 的兩隻腳
5. Input1, Input2 是控制DC Motor輸入訊號, 接到2個GPIO用以控制順、逆、停動作， 為<1,0>或<0,1>, <0,0>
6. 控制4個DC Motor則需要4個PWM 來控制4顆達轉速及8個GPIO 來控制4顆馬達方向
7. 1,2 Enable, 3,4 Enable 都使用，就是 full H-bridge

Motor shield電路圖

https://learn.adafruit.com/downloads/pdf/adafruit-motor-shield.pdf

參考文件: 

1) http://playground.arduino.cc/Main/AdafruitMotorShield

2)  直流馬達的 PWM 調速控制原理 

http://eshare.stust.edu.tw/EshareFile/2010_4/2010_4_ccd9befb.pdf

DEMO:

 Raspberry Pi 連接L293D 控制2顆DC馬達