More Powerful Stepper Motor Drivers

The standard motor drivers (the chips that that plug directly onto the shield) cannot provide sufficient power to the motors for sustaining the weight of the arm. After all, they are designed for low-torque tasks such as in 3D printers. Therefore, we now use a TB6560 stepper motor driver, depicted below, for powering each motor.

Connections for the Stepper Motor Drivers

To connect the more powerful stepper motor drivers to the RAMPS shield, we use the following wiring scheme, minus the breadboard (credit to Jesse Weisberg):

The diagram was designed for a 5 DoF arm (with two paired motors for joint 2), but we have a 6 DoF arm. Therefore, we extend the above diagram with an extra motor using the extender detailed at the bottom of the Hardware Build Log.

Note: our wiring setup uses different colours to that in the above diagram. The mapping from the diagram to our own schema is:

• Orange -> Blue
• Green -> Red
• Blue -> Yellow
• Black -> Black (no change!)

Connecting a Stepper Motor Driver to the RAMPS Shield

Connection on RAMPS side:

Connection on stepper motor driver side:

Note that, as per the wiring diagram, the three black wires connect up together before connecting to the RAMPS shield. This is done as follows:

Connecting a Stepper Motor Driver to a Stepper Motor and Power Supply

The connections on the other side of the stepper motor are depicted below. From left to right: Blue, Red, Green, Black, GND, LIVE.

IT IS VERY IMPORTANT TO GET THE GND AND LIVE WIRES THE RIGHT WAY ROUND, LEST THE ELECTRONICS BE DESTROYED!!

Connecting the Paired Motors

Joint 2 of the arm requires 2 stepper motors, which carry out the same joint command, but one must be in reverse!

First of all, both stepper motors drivers are connected to the RAMPS shield using a mini breadboard:

When connecting the stepper motor driver to the stepper motors, we want the commands for one motor to be reversed in direction. Consider the following diagram:

We see that reversing the polarity of both coil pairs leads to the motor rotating in the same direction, at a 180 degree phase lag. Meanwhile, reversing the polarity of one coil pair leads to the motor rotating in the opposite direction (which is what we want!). Thus, we must swap one pair of wires; we chose the green and black wires.

The connections on the other side of the reversed stepper motor driver are depicted below. From left to right: Blue, Red, Black, Green, GND, LIVE.