Analogue Inputs

Analogue Inputs and +5V External Supply

This is the Analogue commanding port of SOLO, through these inputs/outputs, you can control the Speed or Torque of your motors by sending analogic commands using PWM technique or sending direct analogue voltages from 0V to 5V, you can also use them to limit the current fed into your Motor in completely Analogue Mode ( see the Minimum Required Wirings Section)


This part is composed of 5 pins as can be seen below:

Analogue Inputs 1

1. GND: This is the Ground or in another word the 0V reference of SOLO, so if you want to send an analogue commands to SOLO, you need to make sure the Ground of the commanding unit ( Arduino, Raspberry Pi , … ) is shared with SOLO at this point ( connected together with GND pin).

2. +5V: This is a 5V/1A output to supply external peripherals or controllers, remember that this output is fused, and if you drain more than 1A, the fuse will be blown ( internally ) and this output will become dysfunctional for safety reasons.

3. DIR: This is the Direction control pin which is a digital pin, accepting voltage levels of 0V or 3.3V, so by giving each of these values, the connected Motor to SOLO, will either rotate in C.W. direction or C.C.W. direction.


Remember that DIR pin is NOT 5V tolerant and if you like to connect it to a 5V source, you must use a resistor of a value between 1kΩ to 2.2kΩ (the exact value doesn’t matter, it just must be in this range)

4. P/F: This is a pin with two different functionalities depending on the control Mode

In Open Loop mode of 3 phase motors : it will act as increasing or decreasing the injected power into the Motor, so by applying 0V or 0% duty cycle of PWM, there will be no power injected inside the Motor, and if at 5V or 100% duty cycle of PWM, it will apply the maximum deliverable power into the Motor.

In Closed-Loop mode: it will act as the current Limit, so if the voltage applied to this pin is 5V, it will stop the current floating to the motor ( current Limit at zero), and if this pin is left open it will allow up to 32A floating into your Motor, so any value between these will define the value of current limit. For example if you use PWM method, you can consider that if the duty cycle of your PWM is 50%, then the current limit will be 16A, and if it’s 80% the current Limiti will be at 6.4A. The formula for current Limit in PWM mode is :

The current Limit value = ((100 – duty cycle of PWM at P/F input)/100) * 32

5. S/T: This is the input for controlling the Speed or Torque of the Motor connected to SOLO. in each of these Modes it will act like:

In Torque mode: if you apply 100% duty cycle to this pin, without having a current limit, will try to inject 32A of current inside your motor , and knowing that the amount of Torque has direct relationship with the injected current as :

Applied Motor Torque = Current inside of the Motor* Torque Constant.

In Brushless motors the Current causing the torque generation is known as Quadrature Current.

In Speed mode: if you apply 0V or 0% duty cycle to this pin, it will keep your motor’s speed at 0 RPM, and at the same time by applying 100% duty cycle it will force your motor to go to the maximum speed considered based on the Motor type as below, of course your motor should be able to reach to maximum speed, otherwise it will stay at it’s nominal speed even if you keep increasing the duty cycle. (look at the piano switch settings)

Analogue Inputs 2