Problems with DRV8870 controlling HUINA 580 RC tracked excavator

Thread Starter

Harmen

Joined Apr 5, 2021
1
Hi Guys,

I made a replacement pcb for a Huina 580 RC excavator.

This pcb consist out of a atmega2560 microcontroller controlling 7 DRV8870 H-bridge IC's which there after control all the brushed electric motors on the vehicle.
Alle electric motors turn just fine except the right and left track electric motors.

They make a beeping noise and they wont turn around when i apply a pwm frequency to it.

To verify the engines work i placed a 1.5 V battery and both engines work properly.

Next i applied "full power", so IN1 is high and IN2 is low.
The electric motor makes beeping sound, which i think is quite strange because, i dont apply a frequency on IN1.

Next i applied a the following signals to IN1 while keeping IN2 high
50% duty cycle at 10Hz
50% duty cycle at 100Hz
50% duty cycle at 1kHz
50% duty cycle at 10kHz.

I verified that the microcontroller produced this pwm with an osciloscope.
If you guys wonder how i made this pwm:), well just with the delay function and not using the hardware pwm.
Stil no movement on the motors.

If i check the electric engines, i can see there is en pcb mounted on the back, which looks like a EMI filter?
This was also the reason why i applied different pwm frequencys to the engine.
So i desoldered the passive components from the pcb and found that it make no difference.

At the moment i think something is not going well with the drv8870, despite it is not going into thermal lockdown, or undervoltage lockdown, or over current protection.

What do you guys think? :) ill keep puzzling in meanwhile;)

Kind regards,

Harmen
 
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