MDDS30 unexpected start of motors

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MDDS30 unexpected start of motors

Postby mrz » Sun Jan 17, 2021 7:03 am

I have used the cytron shield-MDD10 without any problems
in PWM / DIR mode (with and without remote control.)
With two slightly more powerful motors I bought the card
Cytron MDDS30 REV 1.3 SmartDriveDuo-30 at
On the first try, there is abnormal behavior.
Arduino Uno MDDS30
GND ---------- GND (GND vertical pin)
4 ------------ IN1
5 ------------ AN1
6 ------------ AN2
7 ------------ IN2
PWM MODE: 101101 10

ARDUINO connected to MDDS30
Battery not connected.
I download the github program from the ARDUINO with a USB cable
( ... rtDriveDuo)
I'm pressing arduino reset.

I plug in the battery, I enter the + RETURN numbers on the screen
Everything is working fine.

I unplug the ARDUINO USB cable and… the MOTORS start to run at full speed !!!
I reconnect the cable to the ARDUINO and they stop after 2s.
(the same behavior several times in a row.)
I press the Arduino RESET / immediately release ==> the motors run for about 2s !.

I DISCONNECT the battery (arduino still connected by USB cable.)
I reconnect the battery.
No access to the program, but if I press RESET (arduino)the 2 motors run for 2s as before!

I unplug the battery
I reload the program on the arduino.
I plug in the battery, the program works.
and if I unplug the arduino cable it starts again as before ...

How do I prevent this unexpected motor start-up when I remove the arduino cable? ...
If I feed the Arduino with a battery, in the same way the motors start if I unplug the battery.
(This event does not occur with the MDD10 shield.)
Thank you in advance.
Posts: 1
Joined: Sun Jan 17, 2021 6:40 am

Re: MDDS30 unexpected start of motors

Postby blueH » Mon Feb 08, 2021 9:49 pm

Try again and always the same problem in PWM mode:
Both motors run when I remove the USB cable from the arduino

I tested the RC control mode with flysky
Correct with choices: CH1/CH2, CH1/CH4, CH2/CH4 on RC1/RC2

I had reported my problem to ROBOTSHOP FORUM
"Hello and welcome to our forum.
We recommend you to contact manufacturer.
They should be able to troubleshoot and help you.
If they determine that device is defective, you can get back to RobotShop and we will do the exchange (if it is bought from RobotShop). "
(Purchase of 12/2020 MDDS30 rev 1.3 SmartdriveDuo-30 )
Motor Controller DC 2x15A, 4.8-35V Product code: RB-Dfr-207)

Do you agree to change my controller card MDDS30
Thank you
Posts: 1
Joined: Thu Feb 04, 2021 7:37 am

Re: MDDS30 unexpected start of motors

Postby waiweng83 » Thu Feb 18, 2021 11:59 am


Sorry for the late reply.
This is expected because when the USB cable is unplugged, the Arduino loss its power and the pins will become floating.
The weak pull up on the motor driver will cause drive the PWM pins to high and causing the motor to run at full speed.

To overcome this problem, please connect a 1K ohm resistor from AN1 to GND and also AN2 to GND.

With the power of dream, nothing is impossible...
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