Is it necessary to use a pull down resistor with this BTS7960?

I have an Arduino Nano controlling a BTS7960 that is 10 meters away.

I have one 24V power supply.

Both the Arduino and the BTS7960 get 5V through a an LM2596 step down converter.

The BTS7960 "Enable" pins are hooked up to 5V output of the step down converter.

My problem is that this setup burnt the BTS7960 Before replacing it, I want to identify what made it burn.

I suspecting that either the RPWM and LPWM became both HIGH (from parasites + long wire ) and burnt the driver so I should add pull down resistors, or there is something wrong with this configuration and using buck converters with common GND is what caused problems.

When I turn on the power supply the motor rotates for few seconds even though the Arduino didn't give orders to turn the motor on yet.

Update :

I changed the setup by adding a second 24V power supply that power the Arduino and the motor driver only, now it's been running for 15 days without any sign of noise signals triggering the motor driver. This may not be the best solution but it seems like it work

• Could well be a ground loop. Is the 24V supply coming from the Arduino side, or the motor side (yes, it matters). Apr 13, 2021 at 14:56
• @tlfong01 Two PWM for the two Direction clockwise and anticlockwise and speed, i'm afraid that my setup and long wires can generate voltages in both PWM pins at same time this will surely burn the driver Apr 13, 2021 at 20:38
• @TimWescott the 24V start from the Arduino side then goes to the Driver and the motor. Apr 13, 2021 at 20:39
• I would consider placing transceivers or line drivers between the arduino and the BTS7960. 10 m is a fairly long distance for the fairly weak arduino outputs. Apr 13, 2021 at 21:47
• How fast are you driving the PWM? It makes a difference as to whether what you're trying is ever going to be feasible without an Arduino right at the motor. Apr 13, 2021 at 23:56

You probably have a ground loop, and it's causing false signalling from the Arduino to the motor driver.

Basically, if you look at your diagram, you need to mentally substitute a string of resistors and inductors for all of the wires. The longer the wire is, the larger the resistance and inductance -- and ten meters is entirely too long for a single-ended logic-level signal.

Communication over that distance, in the presence of a noisy power connection* should either be done with the very careful application of something like RS-232, or -- far better -- with differential signalling (like RS-422) or by carrying the signal ground on a separate wire from the Arduino to the motor driver, and then using opto-isolators at the motor driver.

With your current setup, when the motor is on, and especially when you're driving a PWM signal to it, voltage will appear across your ground wire -- but the signals you're using to the driver board are referenced to the Arduino's ground. If the motor ground drops enough, the signals from the Arduino can both appear to be "on", even if they're not. Moreover, if the driver isn't protected, then the signals can go outside of the voltage range the chip can stand, and fry it on the input side.

Using differential signalling or opto-isolators running off of a separate reference ground from the Arduino will fix that. Using an Arduino on the left side for whatever user interaction you want, with a serial line (that itself uses RS-422) to the Arduino on the right side to drive the motor, will fix that.

You could also just generate 5V at the motor, and power the Arduino with a separate ground wire that's well-isolated from the one driving the motor. As long as you don't have any other ground connections, that may work -- but, 10 meters is a long way for what you're attempting.

Or you could place the motor driver right next to the Arduino, and just run your 10m wires out to the motor. That may actually be the easiest way to accomplish something that's electrically sound.

Having a circuit at the motor driver that won't let you simultaneously drive both half-bridges would be a good thing, too.

* Anything powering a motor is noisy.

• Thank you that is so helpful. if i use Two separate PSU one for the motor one for Arduino and the Driver, will it work without needing to use differential signalling and another Arduino at the driver side ? Apr 13, 2021 at 21:45
• Doesn't work that way. The signalling looks like it's on two wires, but it's between those two wires and ground. Change the ground voltage, and you change what the motor driver sees. Apr 13, 2021 at 23:54
• I had the motor driver right next to the Arduino in my first setup, the issue was the power loss in the long wire, when i attempt to run at 30% speed the driver output is somewhere around 7V but at the end in the motor side the voltage drops to 2 V and i loose all the torque Apr 14, 2021 at 9:01
• Arguably, the correct solution is to not use any hobbyist stuff at all but properly designed PCBs. Ideally with CAN which is more modern and rugged than legacy RS-422. Apr 16, 2021 at 13:59

Question

The OP's BTS7960 DC motor driver module was fried. What can be the possible causes?

1. One possible cause for frying the motor is that the OP uses a wiring and control scheme which might burn for a wrong combination of signals. (See Appendix C for more details. One solution is to use the classic L298N/BTN7961B wiring/control scheme, which I found working OK, so far so good.

2. One workaround for sending signals over 10 metres long distance is to use current loop for not so frequency controls, for example, change motor direction lower than 10Hz.

3. For sending PWM signals over long distance, one solution is to use UART control PWM/sig gen, as described in Appendix A (a)'s Q&A.

4. If the OP prefers the risky connection scheme, it is important to avoid disconnecting motor when power is on, because back EMF spike might go back through ground wire to interrupt the Arduino and cause unexpected control signals to the motor driver and fries it.

5. For the problem: "When I turn on the power supply the motor rotate for few seconds even though the Arduino didn't give orders to turn the motor on yet, ..."

The problem might disappear if Connection/Control scheme #2 is used AND INH pin is pull down to ground.

/ to continue,

Contents

Part A - Possible causes of burning BTS7960 list

Part B - Troubleshoot BTS7960 tips list

References

Appendices


Part A - Possible failure analysis/causes short list

There are many possible causes. Below is a short list.

1.1 My wiring setup.

1.2 My testing setup.

1.3 My input signals.

2.1. Part 2 - How to use L298N input signals, IN1, IN2, and INH

3.1 References: Part C - PWM Full H-bridge Motor Driver

3.2 Appendix A - L298N input signal routing diagram

3.3 Appenidx E - BTN7971B block diagram and input signals

3.4 Appendix L - Calibration of BTN7971B PWM/Duty Cycle (1kHz, 50% Duty cycle) performance

Part B - Troubleshooting Tips List

(1) KISS (Keep It Simple Stupid), Divide and Conquer testing suggestion

1.1 Following my locked answer (Part 1, s1.3) I would suggest to test the BTN7971B dual half bridge modules in two parts, and test only one of the parts, as shown in the figure below:

Notes

1. The right part, half H-bridge #2 in grey, is disconnected (actually only rewiring is to disconnect IN2, input to half H-bridge #2 (IS, INH is common/shared between both half-Bridges). So only the left part, half H-bridge #1, is wired up for uni-direction testing on (a) PWM vs motor speed/efficiency, (b) current measurement using the IS pin only (ie, no clumsy, not so accurate, clamp meter is needed to be used as described in Part 1 (1)).

2. The OP's BTS7960 dual half H-bridge module might have only one of the two half bridges fried. So lucky him might use this wiring diagram to check out if one of the half H-bridge is still alive, and try my suggested tip below to do some investigation research/feasibility studies, as a preparation for (firing) his coming, second new module. :)

/ to continue, ...

References

/ to continue, ...

Appendices

Appendix A - BTS7960 DC Motor Driver Module Schematic - Hanson Tech

Appendix B - BTS7960 DC Motor Driver Module Control Signals - Hanson Tech

Appendix C - Why was the OP's BTS7960 Module Fried?

1. I found the Hanson Tech user guide a bit weird: its control signal names do not correspond to its schematic.

2. Its control procedure is also weird: There are two direction mode enables, one for forward mode, another for backward mode.

My immediate question is this:

what will happen if both forward mode and backward mode are enabled at the same time? Won't the module melt down?

3. So I googled to know more. I had good luck: I found a YT which has a truth table that confirms my worries. See the picture below for what I found! :)

Easy Setup Motor Driver BTN7960/ BTS7960 with Arduino - FireBitLab

Notes

1. This is a very stupid mistake I never expected to see! I need to confirm the OP if what I saw is true!

Appendix D - Two different schemes of control signal/procedure as described by Thai McuCity

Notes

1. The main difference between the two schemes is the following:

(a) Method 1 does not short/combine En_A and En_B, and module would burn if both En_A and En_B are High.

(b) Method 2 shorts En_A and En_B together, the combined En_C is used as a High/Low or PWM signal to Enable/Disable or change speed of the whole module/motor. There is danger of burning the module by wrong combination of En_A and En_B signal.

Appendix E - L298N Connection/Control Signal Scheme Test Results

Using L298N signal and control everything goes well.