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Application Note: Using the Motor

Driver on the 3pi Robot and

Orangutan Robot Controllers

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

2. Motor Driver Truth Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

3. Simple Code to Drive the Motors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

4. Variable Speed Control Using Hardware PWMs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

5. PWM-Based Motor Control Code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

6. Motor Voltage Waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

7. Using the Trimmer Pot for Motor Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

8. Differences between the Orangutan LV-168 and TB6612FNG-Based Controllers . . . . . . . . . . . . . . . . 11

9. Dealing with Motor Noise . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Application Note: Using the Motor Driver on the 3pi Robot and Orangutan Robot

Controllers

Corporation

https://www.pololu.com/docs/0J15/all Page 1 of 12

Summary of content (12 pages)

PAGE 1
Application Note: Using the Motor Driver on the 3pi Robot and Orangutan Robot Controllers © 2001–2015 Pololu Corporation Application Note: Using the Motor Driver on the 3pi Robot and Orangutan Robot Controllers 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2. Motor Driver Truth Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3. Simple Code to Drive the Motors . . . . . . . . . . . . . . . . . . . . . . . . . 4.
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Application Note: Using the Motor Driver on the 3pi Robot and Orangutan Robot Controllers © 2001–2015 Pololu Corporation 1. Introduction Orangutans’ integrated motor drivers set this robot controller line apart from other programmable microcontroller boards like the Basic Stamp and Arduino controllers.
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Application Note: Using the Motor Driver on the 3pi Robot and Orangutan Robot Controllers © 2001–2015 Pololu Corporation 2.
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Application Note: Using the Motor Driver on the 3pi Robot and Orangutan Robot Controllers © 2001–2015 Pololu Corporation 3. Simple Code to Drive the Motors If we don’t want to worry about variable motor speed, we can simply make use of the truth table values in the previous section to figure out how to drive our motors. The code to do this becomes simple AVR digital I/O manipulation: Initialize the motor control pins #include
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Application Note: Using the Motor Driver on the 3pi Robot and Orangutan Robot Controllers © 2001–2015 Pololu Corporation 4. Variable Speed Control Using Hardware PWMs The ATmega48/168/328P used on all four controllers discussed in this app note has two eight-bit timers: Timer0 and Timer2. Each of these timers has two PWM output pins. The Timer0 PWM output pins are OC0A on PD6 and OC0B on PD5; these are the control lines for motor 1.
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Application Note: Using the Motor Driver on the 3pi Robot and Orangutan Robot Controllers © 2001–2015 Pololu Corporation 5. PWM-Based Motor Control Code #include // Motor Control Functions -- pwm is an 8-bit value // (i.e.
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Application Note: Using the Motor Driver on the 3pi Robot and Orangutan Robot Controllers { © 2001–2015 Pololu Corporation motors_init(); M1_forward(128); // motor 1 forward at half speed M2_reverse(25); // motor 2 reverse at 10% speed delay_ms(2000); // delay for 2s while motors run M1_reverse(64); // motor 1 reverse at 25% speed M2_forward(0); // motor 2 stop/brake // loop here forever to keep the program counter from // running off the end of our program while (1) ; } return 0; 5.
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Application Note: Using the Motor Driver on the 3pi Robot and Orangutan Robot Controllers © 2001–2015 Pololu Corporation 6. Motor Voltage Waveforms The following oscilloscope screen captures demonstrate how our motor control functions from Section 5 affect the motor driver outputs. These captures were taken using an Orangutan LV-168 running off of three AA batteries with a free-running motor connected. At 6 V, the motor has an approximate free-run current of 400 mA and stall current of 7 A. A single 0.
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Application Note: Using the Motor Driver on the 3pi Robot and Orangutan Robot Controllers © 2001–2015 Pololu Corporation M1_reverse(63); Motor outputs M1A (blue) and M1B (yellow) for driving “reverse” at 25% duty cycle (OCR0B=63, OCR0A=0). The green channel shows motor current. If you use the Pololu AVR library, the equivalent function call would be set_m1_speed(-63). (see the Pololu AVR command reference [http://www.pololu.com/docs/0J18/7] for more information).
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Application Note: Using the Motor Driver on the 3pi Robot and Orangutan Robot Controllers © 2001–2015 Pololu Corporation 7. Using the Trimmer Pot for Motor Control The following sample program uses the motor control functions defined in Section 5 to drive the motors in response to the trimmer potentiometer position. Motors 1 and 2 transition linearly from full forward to stationary to full reverse as the potentiometer voltage varies from 0 to 5 V.
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Application Note: Using the Motor Driver on the 3pi Robot and Orangutan Robot Controllers © 2001–2015 Pololu Corporation 8. Differences between the Orangutan LV-168 and TB6612FNG-Based Controllers Everything mentioned so far in this application note applies to both the Orangutan LV-168 and the TB6612FNG-based controllers, but there are some key motor control differences that need to be noted: Orangutan LV-168 motor voltage 2-5 V Baby Orangutan B, Orangutan SV-xx8, and 3pi robot 6-13.
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Application Note: Using the Motor Driver on the 3pi Robot and Orangutan Robot Controllers © 2001–2015 Pololu Corporation 9. Dealing with Motor Noise One major drawback to working with motors is the large amounts of electrical noise they produce. This noise can interfere with your sensors and can even impair your microcontroller by causing voltage dips on your regulated power line. Large enough voltage dips can corrupt the data in microcontroller registers or cause the microcontroller to reset.