Microcontroller keep resetting during DC motor operation

Dear All,

Currently i'm facing problem the problem with the P89C51RD2HBA where it keep resetting whenever the DC motor turn ON. The board can actually drive 5 DC motors, I can send command to turn on and off for each DC motors. However, the MCU start to reset after all 5 DC motors turn ON for few minutes (2minutes). The DC motor used drawn out current of 130mA each, and main DC supply to this board is 24V/5A.

The reset circuit on the board using electrolytic capacitor 10uF/25V and resistor of 2.2k with respect to ground.
* I also just added a diode 1N4148 with anode connected to ground and place parallel with the 2.2k resistor.

Is the problem related due to noise that comes when the DC motor starts to run? However, even though i just turn on only 3 DC motor, the MCU keep resetting after few minutes the DC motor running.

I also attached the schematic and the pcb layout of the problematic board.

Any help highly appreciated.

Thank you very much.

I also attached the schematic and the pcb layout of the problematic board.

Click to expand...

Not yet.

Resetting after several minutes doesn't sound primarly suggest a "noise" problem. Rather a supply problem, resulting in voltage drop. Or a software related issue.

Hi FvM

Thank you for your replied. I also already tried to separate the supply to DC motor and the MCU, with common ground, but the problem still exist.
I don't think that the software/firmware was the problem since the firmware tested with the other board and it's working fine.
Using the oscilloscope, i do not see any voltage drop to the MCU that can caused MCU to reset. However, I'm still checking if there is volatge drop at the reset pin.

Thanks.

1. For a reset circuit, using a 10uF cap is not common unless you have a strong reason for it. Try using 1nF or 100nF ceramic cap instead and see if it improves the behavior.
2. Add sufficient bypass caps at the micro power supply pins.
3. You can probe the micro power supply line during the operation to see if the power to the micro is getting affected.

You did not attach any file. Also attach complete C code.

I had faced a similar kind of problem. The solution is to separate the analog ground of your motor power supply and digital ground of your microcontroller with a PTC device i.e. Positive temperature coefficient. It provides high impedance whenever analog circuit generates spikes and doesn't allow it to reach controller, otherwise there is a short between it's two terminals. The one which I used is at:
https://www.mouser.in/ProductDetail...LVR012K/?qs=eE3j%2bwSf/WNUIRQaKxrYTQ==&_cdc=1

Other options may include attaching capacitors between one motor terminal and body of motor and capacitors on the supply of motor (they can be electrolytic).
You can also provide some delay for stabilization of supply voltage. This can be possible reason also. Changing the direction of motor from maximum speed in one direction can also generate such spikes. Try to avoid it.

chiart said:

Is the problem related due to noise that comes when the DC motor starts to run? However, even though i just turn on only 3 DC motor, the MCU keep resetting after few minutes the DC motor running.

Click to expand...

Most of the time this problem came due to old motors (or used DC motors). Usually, due to inrush current this problem is happened, If you reduce the DC motor operating voltage then u may overcome this problem.