I am trying to drive 298:1 Micro Metal Gearmotor using your TB6612FNG motor driver circuit.
My aim is just to drive the motor forward and reverse at some constant speed. I do not need to use PWM control.

I am using 16F877 PIC.

I did the following:

  1. PWMA set at constant high. ( I am assuming this will drive the motor at constant top speed)

  2. STBY input set to high.

  3. Vcc at +5V, VMOT at +6V ( 298:1 Micro Metal Gearmotor is a 6V motor)
    , and all GND grounded.

  4. Motor connected across A01 and A02

I am trying to vary the inputs to AIN1 and AIN2, but the outputs at A01 and A02 are always low, hence no motor rotation at all.

Is there anything wrong with the connections I have made?


The connections as you describe them are correct. To drive a motor connected across AO1 and AO2, you want to have STBY high, PWMA high, and AIN1 = !AIN2 (so either AIN1 high and AIN2 low, or AIN1 low and AIN2 high). Make sure you have grounds from both your logic supply and motor supply connected to the board.

- Ben

Thanks for the help. However, the problem still persists.
I am reading off the following voltages from the pins:
Vcc = +5V
AIN1= +5V
BIN1 , BIN2, PWMB not connected
VMOT = +5V

I am using a common supply for Vcc and VMOT and both are grounded together.

The Voltages at A01 and A02 are around 0.03V.
I am not even using a microcontroller at this stage. I am just giving logic high and low to the input pins manually.

My next suggestion is you perform this test for all four possible permutations:

AIN1 high, AIN2 low, PWMA high
AIN1 low, AIN2 high, PWMA high
BIN1 high, BIN2 low, PWMB high
BIN1 low, BIN2 high, PWMB high

Are you using a lab supply that reports how much current is being drawn? If so, are you seeing an unusual spike in current when you perform any of these tests, or does the board get hot at all (please be careful not to burn yourself!)?

- Ben