DFRobot 2A motor driver

Help & Support Robot Parts
1

I’ve spent a day with an Arduino Uno and the DFRobot Arduino compatible motor shield.
[robotshop.com/eu/productinfo.aspx?pc=RB-Dfr-58&lang=en-US](https://www.robotshop.com/eu/productinfo.aspx?pc=RB-Dfr-58&lang=en-US)
I looked at the schematic diagram, thoroughly read the L298P datasheet and wrote some sketches to make it work. Everything works but I don’t understand why the DFRobot webpage says this motor shield “Supports PWM and PLL (Phased Locked Loop) control modes”.

I’m an electrical engineer - technical writer and I know what a PLL is but I as far as I have understood the shield does not hold any PLL components. The motor current sense resistors discussed in the L298P datasheet are not present on the shield, no motorcurrent feedback whatsoever is available so no feedback = no PLL.
The L298P datasheet does not mention PLL either.

Switching the jumpers from PWM to PLL only swaps the PWM control line with the Enable line but that has nothing to do with PLL, it’s still PWM but the motor direction can also be controlled by the PWM signal.

Can somebody explain why it’s called PLL ?

2

I’ve spent a day with an Arduino Uno and the DFRobot Arduino compatible motor shield.
[robotshop.com/eu/productinfo.aspx?pc=RB-Dfr-58&lang=en-US](https://www.robotshop.com/eu/productinfo.aspx?pc=RB-Dfr-58&lang=en-US)
I looked at the schematic diagram, thoroughly read the L298P datasheet and wrote some sketches to make it work. Everything works but I don’t understand why the DFRobot webpage says this motor shield “Supports PWM and PLL (Phased Locked Loop) control modes”.

I’m an electrical engineer - technical writer and I know what a PLL is but I as far as I have understood the shield does not hold any PLL components. The motor current sense resistors discussed in the L298P datasheet are not present on the shield, no motorcurrent feedback whatsoever is available so no feedback = no PLL.
The L298P datasheet does not mention PLL either.

Switching the jumpers from PWM to PLL only swaps the PWM control line with the Enable line but that has nothing to do with PLL, it’s still PWM but the motor direction can also be controlled by the PWM signal.

Can somebody explain why it’s called PLL ?

3

Sounds like an issue with the code. Try one channel at a time. We’ll also assume you don’t have a load connected to the motors and they can spin freely. Disconnect everything else from the setup so you only have the Arduino, shield, motors and power supply. Power the Arduino from the USB. If you wrote your own code, try the basic code for the shield first. Last, ensure the pins you are using correspond to the jumpers on the shield; you need two specific PWM pins on the Arduino and also two digital pins (any of them) to power the two channels on the controller. We await your reply.

4

You will find here how to use the PLL control method and a bit of info on how it works: dfrobot.com/wiki/index.php?title=Arduino_Motor_Shield_%28L298N%29_%28SKU:DRI0009%29

Also, for the first issue using two motor controllers, it is a bad idea to connect both motor controllers in parallel as you are doing. If you need to output a max of 4A instead of 2A, we recommend getting a more powerful motor controller. Connecting their outputs together will mess up with their control signals, and input impedance.