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
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 meanwhileKind regards,
Harmen
