The SPARK MAX can accept data from encoders through both the Encoder Port and the Data Port on the top of the motor controller. Encoders have a different method of connecting to the SPARK MAX that depends on what motor you are using and what type of encoder it is. When preparing your encoders, be sure to set up your SPARK MAX correctly for the type of devices you are using.

Incremental vs Absolute Encoders

Incremental encoders measure a change in position as a mechanism rotates while absolute encoders will report an exact position at any time, including at startup. A common analogy to help with knowing the difference is that incremental encoders are like a stopwatch that measures a change in time and absolute encoders are like a clock where you can know exactly what time it is.

With SPARK MAX Firmware Versions 1.6.0 and newer, absolute encoders are compatible with the SPARK MAX Data Port.

How to Connect an Encoder

To connect an encoder to your SPARK MAX, start by identifying what type of encoder you are using. Below is a flowchart to help generally identify the method you should use.

Absolute Encoders

Absolute encoders will work with the default pinout of the SPARK MAX Data Port if the latest firmware has been installed. When using an absolute or duty cycle encoder it is recommended to use one of the following methods to connect your encoder to the SPARK MAX.

• : Connect with

• Other Absolute Encoder: Connect with

  • Use the Data Port Pinout to match the signals from your encoder

If you are using an Incremental Encoder with a brushed motor you can plug your encoder into the SPARK MAX's front Encoder Port directly. If you are driving a NEO or NEO 550 brushless motor with your SPARK MAX, you will need to configure Alternate Encoder Mode to accommodate the additional encoder input from the Data Port. When using an incremental or quadrature encoder it is recommended to use one of the following methods to connect your encoder to the SPARK MAX.

• or Internal Encoder: MUST be connected to the SPARK MAX Encoder Port

• • With brushless motor: Connect with . You will need to configure Alternate Encoder Mode.

Receiving both Incremental and Absolute encoder feedback from a single encoder through the SPARK MAX directly is not currently supported. To do this you will need to wire the encoder directly to your roboRIO or robot controller.

Currently, Limit Switch inputs are only supported when using an absolute encoder or an incremental encoder run through the SPARK MAX's Encoder port. Please note, the limit switch inputs cannot be used at the same time as an Alternate Encoder Mode. The limit switch pins are repurposed for the alternate encoder and are thus disabled.

The SPARK MAX does not need to be configured to a specific mode to accept input from an absolute encoder as long as the encoder is connected to the SPARK MAX Data Port.

Absolute Encoder Specifications

Connecting an absolute encoder that is not a Through Bore Encoder will likely require a custom wiring harness or to connect the necessary encoder power, ground, and signals to the SPARK MAX Data Port. When using an Absolute Encoder use the following pinout information for the Data Port:

The Encoder Adapters and SPARK MAX Data Port Breakout Boards can be secured to a SPARK MAX in two ways.

SPARK MAX Mounting Bracket ()

A zip-tie can be secured around the SPARK MAX's zip-tie notches and over the board to securely attach it to the motor controller as well.

The SPARK MAX can be configured to run in Alternate Encoder Mode, which reconfigures the Data Port on the top of the controller to accept an alternative quadrature encoder, separate from the default encoder inputs shared between the front Encoder Port and the default quadrature encoder Data Port pins. Analog input is not affected by Alternate Encoder Mode.

Alternate Encoder Specifications

When configured for Alternate Encoder Mode, a quadrature encoder connected to the reconfigured Data Port pins can be used as a feedback device by the SPARK MAX. Please note, the limit switch inputs cannot be used at the same time as an alternate encoder. The limit switch pins are repurposed for the alternate encoder and are thus disabled. Please see for for more information.

Connecting an alternate encoder will likely require a custom wiring harness to connect the necessary encoder power, ground, and signals to the reconfigured Data Port. When configured in Alternate Encoder Mode, the Data Port has the following pinout:

Use an Alternate Encoder Adapter () to connect a directly to the SPARK MAX Data Port. This adapter has a JST PH 6-pin connector that is compatible with the Through Bore Encoder's pinout and a selection switch to change the signal that is connect to pin 4 of the data port.

Another option is the . This board can be used to wire an alternate encoder to the Data Port. The following table describes which pads on the breakout should be used for which signals coming from the alternate encoder.

Below you will find the steps required to set up and use the Alternate Encoder Mode on the SPARK MAX, starting with configuration through either the REV Hardware Client or the SPARK MAX APIs.

Using the REV Hardware Client, select your SPARK MAX, then navigate to the Advanced Tab and scroll to the Alternate Encoder parameter section. Enable the alternate encoder by setting the kDataPortConfig parameter to 'Alternate Encoder' via the drop down menu. You can also set the other Alternate Encoder parameters at this time.

If using the SPARK MAX APIs, the Alternate Encoder is automatically configured when the Alternate Encoder object is instantiated. An Alternate Encoder is created the same as a CANEncoder, either by directly using the constructor or calling GetAlternateEncoder() on a previously constructed CANSparkMax.

Currently, quadrature is the only available type of configuration for an alternate encoder. This is differentiated from the other types of encoder configurations available for an encoder connected through the front facing Encoder Port on the SPARK MAX.

Since the alternate encoder inputs and the default digital inputs are shared on the Data Port, the user cannot use both the alternate encoder and a digital inputs in code. Therefore, a std::invalid_argument (C++), IllegalArgumentException (Java), or an Error on the Error Out terminal (LabVIEW) will be thrown if a user tries to construct both types objects in code simultaneously.

The alternate encoder can be used with the different closed-loop control modes available on the SPARK MAX. The feedback device used by a CANPIDController must be set to use the alternate encoder through SetFeedbackDevice().

Unlike the built-in sensor on the NEO Brushless motors, the 'phase' of the alternate encoder is unknown to the SPARK MAX. Before enabling any closed-loop control, it is critical that the phase is configured correctly. To verify:

1. Configure and connect the sensor as a quadrature alternate encoder, but do not run a closed-loop mode.

2. Plot the output signal of the motor using GetAppliedOutput() and the output of the encoder using altEncoder.GetVelocity(). Confirm that the sensor is behaving as expected. This can be done on the SmartDashboard: frc::SmartDashboard::PutNumber("Alt Encoder Velocity", m_alternateEncoder.GetVelocity()); frc::SmartDashboard::PutNumber("Applied Output", m_motor.GetAppliedOutput());