Are these H-Bridges correct?

[MikeMl]

Hm, I don't quite understand how it only uses two Arduino pins - there are Ports A, B, C, and D, right?

Yes in the schematic I posted; no in the circuit I described in the last paragraph of post #19.

Here is the schematic of how to reverse a DC motor, and do PWM on it using only two Arduino pins. I also show how to monitor the motor current using an Arduino A/D pin. This is part of a swing gate controller I built this summer. Reversing happens only after the gate stops moving, so relay is fine for the task. Relay is DPDT with 12Vdc coil.

The PWM is used to soft-start (accelerate) and soft-stop (deaccelerate) the motor. Current sensing is used to detect that the gate ran into an obstacle, and that the motor has coasted to a stop before reversing direction.

Also shown is the correct grounding scheme for the Arduino pcb to keep motor and relay currents from flowing along the Arduino ground traces...

.

 

[Jacky Lee]

Ooooh, okay

That diagram is out of my scope of knowledge so it's quite confusing to me hopefully in a few weeks or months I'll have a better grip of electronics

 

[MikeMl]

Ooooh, okay

That diagram is out of my scope of knowledge so it's quite confusing to me hopefully in a few weeks or months I'll have a better grip of electronics

What are you having trouble with?

 

[Jacky Lee]

What are you having trouble with?

Well, the main problem is that I'm in an Intro to Engineering Design class, and all they give us are videos to watch to learn the material. My professor doesn't exactly supplement these videos with appropriate lectures, so the burden of learning has mostly been on myself. We are building a basic vehicle, and I am completely new to electronics (but I was assigned to electronics by my group).

 

[MikeMl]

Are you having trouble reading schematic diagrams?

 

[Jacky Lee]

Sort of. I don't exactly know all the symbols, and or particularly how electricity flows through a current.

 

[crutschow]

Below is the simulation of a bridge circuit that uses only two inputs, one to control direction and one to control the application of motor power.

Only one bridge MOSFET needs to be externally switched. The other MOSFETs are controlled by the bridge opposite-side output voltages, avoiding the requirement for separate gate control signals or level shifters.

A separate MOSFET (M5) is used to control the power to the bridge by input "Mot_On". Thus the bridge can reverse motor direction under control of input "Mot_Dir" during the time the bridge is unpowered to avoid any significant shoot-through currents or spikes when the bridge is reversed.

Just make sure that the bridge is off for a sufficient period of time to allow the motor to stop before the direction is reversed.

Note: The simulated motor has an arbitrary series resistance of 2.5 ohms and an inductance of 10mH.

 

[MikeMl]

Below is the simulation of a bridge circuit that uses only two inputs...

Zapper,

Would you be willing to post the .asc?

 

[crutschow]

Here it is.
H-Bridge -2 Input Mot. Dir.asc

 

[camerart]

Comment removed as it has already been covered.