how do I use the REV through bore encoder

Wiring and Connection

To use the REV Through Bore Encoder, plug it into the encoder ports located near the motor ports on the expansion hub . Because the encoder has a high number of Counts per Revolution (CPR), it can lose steps if plugged into ports 1 or 2 .

Operating Mode

In the FIRST Tech Challenge control system, the REV Through Bore Encoder is used as a relative, incremental encoder using the quadrature communication protocol . Although the encoder supports absolute positioning, this capability is only available over PWM, which is inaccessible within the FTC control system .

Programming and Reading Data

Reading Position: Call the getCurrentPosition() method on the DcMotor object associated with the port where the encoder is plugged in .
Resetting Position: Use STOP_AND_RESET_ENCODERS to reset the encoder position to zero at the beginning of an OpMode . Otherwise, the position remains relative to the initial position of the shaft when the robot was powered on .
Velocity Warning: Avoid calling getVelocity() on a DcMotorEx object with this encoder, as its high CPR can cause the returned 16-bit signed integer to overflow .

Additional Resources

For more specific details on different versions and control systems, refer to these restricted documents:

Was this right?

Sources16

Through Bore Encoder | REV DUO Control System

This source does not publish a licence, so its text is not reproduced here. Open the source to read it.

Open REV Robotics Docs

Through Bore Encoder V2 | REV Crossover

This source does not publish a licence, so its text is not reproduced here. Open the source to read it.

Open REV Robotics Docs

Through Bore Encoder | REV ION Control System

This source does not publish a licence, so its text is not reproduced here. Open the source to read it.

Open REV Robotics Docs

Through Bore Encoder V1 | REV Crossover

This source does not publish a licence, so its text is not reproduced here. Open the source to read it.

Open REV Robotics Docs

Encoders (Rotation Counters)

FTC Docs·BSD 3-Clause

REV HD Hex Motor

^^^

+++

Built-in Encoder in the REV HD Hex Motor

REV Through Bore Encoder

^^^

+++

REV Through Bore Encoder, in incremental mode.

An encoder is a device that measures the rotational displacement around an axis. Most legal FIRST Tech Challenge motors contain a built in quadrature encoder that is compatible with a REV Hub. It is also possible to use a standalone incremental encoder like a REV Through Bore Encoder (shown above). An incremental encoder works by sending out a "tick" per partial rotation of the shaft. More information on how many ticks are output per rotation can be found on the manufacturer's website. An absolute encoder is able to indicate the displacement of the shaft from its starting position and the the exact angle the shaft is currently at relative to a "zero" position.

Open FTC Docs

Encoder Port | REV ION Brushless

This source does not publish a licence, so its text is not reproduced here. Open the source to read it.

Open REV Robotics Docs

Absolute Encoders | REV ION Brushless

This source does not publish a licence, so its text is not reproduced here. Open the source to read it.

Open REV Robotics Docs

MAXSpline Encoder | REV ION Control System

This source does not publish a licence, so its text is not reproduced here. Open the source to read it.

Open REV Robotics Docs

Sensor Glossary > Encoders/Potentiometers

Game Manual 0·CC BY-NC 4.0

Rotational
Absolute (+ Potentiometers)
MA3 (am-2899 (https://andymark.com/products/ma3-absolute-encoder-with-cable))
Potentiometer (REV-31-1155 (https://www.revrobotics.com/rev-31-1155/))
Relative
REV Through Bore Encoder (REV-11-1271 (https://www.revrobotics.com/rev-11-1271/)). It has absolute support but over PWM, which is inaccessible within the FTC control system.
E4T (am-3132 (https://andymark.com/products/e4t-oem-miniature-optical-encoder-kit))
Generic (Sparkfun Rotary Encoder (https://www.sparkfun.com/products/9117))
Positional
Linear Potentiometers Slide Pot (Sparkfun Slide Pot (https://www.sparkfun.com/products/9119))

Open Game Manual 0

Using Encoders with the SPARK MAX | REV ION Brushless

This source does not publish a licence, so its text is not reproduced here. Open the source to read it.

Open REV Robotics Docs

Reading and Writing to Hardware > Examples of Using Common Hardware Components > DC Motor > Encoders

Game Manual 0·CC BY-NC 4.0

Term: Encoder — An encoder refers to a device that tracks (generally) rotational movement around an axis.

There are both absolute and relative encoders. An absolute encoder will report at exactly what angle the shaft is compared to its absolute "zero". A relative encoder will report how far the shaft has rotated since it started tracking (for example, when autonomous starts). Relative encoders will have a quadrature output, whereas absolute encoders generally have analog or i2c outputs.

Encoders are used to help find the position of where the robot, or one of its mechanisms, is.

While all FTC legal motors contain built in relative quadrature encoders, they must be wired separately and are not required for use. External encoders may be used and plugged into an encoder port so long as they use the quadrature communication protocol.

Accessing encoders requires calling one method on the DcMotor object, getCurrentPosition(), which returns the current position of the encoder plugged into the port. This number may be arbitrary at the beginning of an opmode, and is not reset to 0 unless STOP_AND_RESET_ENCODERS is used or power is cycled to the expansion hub.

Important: There is no real standardized terminology when dealing with quadrature encoders. The SDK uses "CPR" or Counts Per Revolution by default,. You may also see some datasheets list "PPR" or Pulses per Revolution. One pulse can be equivalent to anywhere from 1 to 4 SDK "counts". Be careful when reading datasheets!

Warning: Encoders with high numbers of Counts per Revolution, such as the REV Through Bore Encoder, can lose steps if plugged into ports 1 or 2. In addition, calls to getVelocity() on a DcMotorEx object may overflow with high counts per revolution encoders, due to the returned number only being a 16 bit signed integer.

Open Game Manual 0

Encoders > What Are Encoders? > Relative Encoders

Game Manual 0·CC BY-NC 4.0

Ranging from the built in encoder in every FTC legal motor to common external encoders like the REV Through Bore encoder, these encoders track the relative position of the shaft or mechanism they are attached to. What this means is that the position output is relative to the initial position at robot power on, meaning position information is lost between power cycles.

Tip: Relative encoders don't reset to zero at the beginning of OpModes! You can use STOP_AND_RESET_ENCODERS to ensure that your encoders are always at zero at the beginning of an OpMode (see below).

All relative encoders in FTC use the "quadrature" protocol to send position information to the expansion hub. As a result, relative encoders must be plugged into the encoder ports located near the motor ports in order to function.

Open Game Manual 0

Alternate Encoder Mode | REV ION Brushless

This source does not publish a licence, so its text is not reproduced here. Open the source to read it.

Open REV Robotics Docs

2 Motor Gearbox - Through Bore | REV ION Build System

This source does not publish a licence, so its text is not reproduced here. Open the source to read it.

Open REV Robotics Docs

Dead Wheels > Encoders > U.S. Digital E8T (deprecated)

Game Manual 0·CC BY-NC 4.0

Once the de facto option for most FTC teams, the E8T (https://www.usdigital.com/products/encoders/incremental/kit/E8T) optical encoders are no longer recommended as the REV Through-Bores are a superior option at an equivalent price. The open-hole optical disc design of these encoders face a number of frustrating design flaws that made them very fragile and prone to breaking. The only advantage that they have relative to the REV Through-Bores is their smaller footprint.

(Figure: E8T Encoder)

Open Game Manual 0

Encoder Basics | REV DUO Control System

This source does not publish a licence, so its text is not reproduced here. Open the source to read it.

Open REV Robotics Docs