Pololu 3pi Robot Manual do Utilizador descarregar pdf (Página 15)

If switches 1 and 4 are closed (the center picture), current flows through the motor from left to right, and the motor

spins forward. Closing switches 2 and 3 causes the current to reverse direction and the motor to spin backward. An

H-bridge can be constructed with mechanical switches, but most robots, including the 3pi, use transistors to switch

the current electronically. The H-bridges for both motors on the 3pi are all built into a single motor driver chip, the

TB6612FNG, and output ports of the main microcontroller operate the switches through this chip. Here is a table

showing how output ports PD5 and PD6 on the microcontroller control the transistors of motor M1:

PD5 PD6 1 2 3 4 M1

0 0 off off off off off (coast)

0 1 off on on off forward

1 0 on off off on reverse

1 1 off off on on off (brake)

Motor M2 is controlled through the same logic by ports PD3 and PB3:

PD3 PB3 1 2 3 4 M2

0 0 off off off off off (coast)

0 1 off on on off forward

1 0 on off off on reverse

1 1 off off on on off (brake)

5. How Your 3pi Works Page 15 of 63

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Pololu 3pi Robot Manual do Utilizador Página 15