from Encoders or Hall sensors either can have 3.3V or 5V levels. The digital inputs are internally pulled-up to +5V with 1kΩ resistance to provide 5mA current for open drain/collector configurations.
1. Connection of Quadrature Encoders to SOLO
SOLO can control the speed, torque ro position of your motor using quadrature encoders, but despite sensorless methods, when we use encoders, the connection of Encoder to SOLO is will affect the order of wiring and how you should connect your motor’s phases to A, B and C output of SOLO.
In a quadrature encoder, we have two pulses that have 90 degrees of phase shift with respect to each other and you should connect both of these to SOLO to “Encoder_CHA” and “Encoder_CHB” , these pulses are generated based on the number of slots provided on the optical encoder disk. The Index pulse on the other hand, is generated every rotation once, and as far as SOLO concerns, it’s not mandatory to use it, as it plays a corrective measure role in position controlling methods, if your encoder has this output you can connect it, if not, still no problem.
The standard way of finding the correct Encoder connection to SOLO can be done depending on the type of the Motors and you can go as following:
1.1. Connect the +5V output from SOLO to supply your encoder (if needed)
1.2. Make sure the Ground of pin of SOLO (pin number 6) is at least connected to your encoder Ground at 1 point
1.3. Find the order of A,B,C connection to your motor based on the following guides for 3-phase or DC brushed motors
2. Encoder Connection for BLDC, PMSM and ACIM motors (3-phase Motors)
For these types of Motors the connection is as below:
2.1 The leading phase of the Motor in one specific rotational direction( in our case C.C.W direction when the motor shaft is facing you) should be connected to output “A”, then the next phase behind the leading phase to “B” and the last phase connected to output “C” of SOLO.
As can be seen in Figure 4, the phase 3 in BLUE is leading the other two phases in one specific direction, so in our case it should be connected to the output “A” of SOLO, and then RED and Black are connected to output “B” and “C” respectively.
To find out the order of the phases in your 3-phase motor you can do:
2.1.1. Check the datasheet of Motors, it might be mentioned there(in C.C.W direction)
2.1.2. Connect the 3 wires of the motor to the Oscilloscope and try to turn the shaft in the Counterclockwise direction while the shaft is facing you, then you should see the order of phases on the screen as the BEMF voltage will appear. Connect the Motor based on this order to the Motor outputs of SOLO as mentioned above and record which pulse of Encoder Leads in this condition ( Pulse A or Pulse B )
2.2 The Encoder Leading pulse relative to the leading phase connected to Motor output “A” of SOLO, should be connected to input “Encoder_CHA” and the next pulse should be connected to the “Encoder_CHB” inputs of the encoder connector. This means that while the Phase of the motor connected to output “A” leads the rest in C.C.W. direction, the pulse going to “Encoder_CHA” is also leading the pulse going to “Encoder_CHB” in encoder input.
3. Encoder Connection for Brushed DC motors
For DC motors if you want to control the Speed using encoders, the order of the connection of Encoder pulses or the Motor wires is not important, so you can just connect the Motor to outputs “B” and “C” of SOLO plus the Encoder connected to “Encoder_CHA” and “Encoder_CHB” inputs of the encoder connecter, While if you want to use the position Control you must follow the following procedure to correctly connect the Encoder to SOLO:
3.1. After supplying your Encoder with +5V from SOLO or externally, Connect the Motor to SOLO and Turn the Motor in Counter Clockwise direction , you can just run SOLO in open loop mode to move your motor in C.C.W direction, or you can do this manually.
3.2. Observe which Pulse of the Encoder’s output leads the other one in this counter clockwise direction while the shaft of the motor is facing you. After finding out, you need to connect the leading pulse to “Encoder_CHA” and the other pulse to “Encoder_CHB” inputs of SOLO. The output wires order to the Motor from SOLO after this step should remain unchanged.