While there are many errors one may run into in the programming and software world we're going to focus for now on the two major errors that may occur when hardware mapping.
Interface Errors - errors between how an interface should work and how it actually behaves
Runtime Errors - errors that occur when a program is being executed
Interface errors occur in the SDK when the parameters of the SDK interface are not met. These errors are more common in Blocks due to it handling much of the hardwareMapping process for the user.
Below you can see a comparison of Blocks when a configuration file is not selected (left) versus when one is active (right):
Within the SDK runtime errors occur during initialization or run. One of the most common runtime errors within the Control Hub can be seen below:
There are a few different reasons this error typically occurs:
No configuration file is currently active or created
The incorrect configuration file is active
There is a mismatched name between the configuration file and code (ex: rightmotor vs right_motor)
What results is when the program begins the robot is forced to stop running when the first hardware device is not properly identified. That first hardware device is the one indicated in the error. If there are multiple issues the next will show once the initial is fixed.
A similar error may occur when using OnBot Java, which will appear like the following:
Similarly, this error is likely due to a typo or mismatched name between the program and configuration file. I can see in the error that I've accidentally set my motor to be named "test_moto" instead of "test_motor"!
There are many errors that could appear while compiling, however let's look at a common one for the hardwareMap.
Looking at line 48 of the program we can see the following:
In this scenario, the name from the configuration file is correct within the string, however the variable name is wrong.
Remember to click the "Build Everything" button to compile your program after making changes!
Before we can truly dive into programming our robot, we need to help our robot's brain, the Control Hub, to know what is connected to it. Through the configuration process we can tell the Control Hub which port sensors, motors, servos, and any other connected devices can be found.
This is one of the most important steps to always complete BEFORE you can start programming!
While every REV Control Hub is the same, the robots being controlled by the Control Hub are not. Each Control Hub has the same number of motor ports, servo ports, digital ports, and the like, but how you may utilize these ports varies from system to system. For instance, a Color Sensor V3 may be plugged in to I2C Bus 1 on one person's Hub, but another might use the same bus to host a 2m Distance Sensor.
While the Control Hub may know there is a device attached to a port, it doesn't instinctively know which information needs to be transferred back for use in an OpMode. To help our robot out we need to complete a process called hardware mapping. This is a two step process that includes creating our configuration file using the Driver Hub and calling the hardware map within our OpMode.
When using Blocks, this second step is handled for the user by the tool. However, in OnBot Java it is up to us as the programmer to create our variables and assign an external hardware unit.
Select the menu in the stop right corner of the Driver Station app. Then select Configure Robot.
In the Available configurations page, select New.
In the USB Devices in configuration page select the Control Hub Portal.
Note: If you have an Expansion Hub connected it will appear as an Expansion Hub Portal.
Pressing "Scan" on an existing configuration may result in the already named devices being erased. A new configuration file is needed when adding a camera or Expansion Hub.
Within the Hub Portal select the device you want to configure. In this use case, select the Control Hub.
Note: if you have an Expansion Hub connected to a Control Hub, the Expansion Hub will also appear as a configurable device in the portal.
This will bring you to the page shown in the image. From here you can configure motors, servos and sensors that you are using. Follow through the rest of the guide to figure out how to configure devices that will be used in the Test Bed section.
Note: The way that Digital and Analog devices are configured versus how I2C devices are configure differ significantly. This is because each physical I2C port is a different bus that can host multiple different sensors. For more information on the different types of sensors check out the sensors section.
The following section will show how to configure components that will be used in the Test Bed. The hardware type and names have been chosen in consideration for the Hello World lesson plan. Users should heed notes within the steps to consider when creating configuration files for other instances.
Select Motors.
The Motor page will allow you to configure all four motor ports on the Hub. On Port 0 open the drop down menu and select REV Robotics Core Hex Motor.
Note: In your configuration file you should configure the motor ports to the type of motor you are using.
Name the motor test_motor. Select done.
Note: remember when naming hardware in the configuration file that the REV Control System is Case Sensitive.
Select Servos.
The Servo page will allow you to configure all six servo ports on the Hub. On Port 0 open the drop down menu and select Servo.
Note: REV Servos can be configured as a Servo or a Continuous Rotation Servo. The type of device a servo is configured as should correspond with the mode the sensor is in. For more information on Sensor modes visit the Sensor section.
Name the servo test_servo. Select done.
Note: remember when naming hardware in the configuration file that the REV Control System is Case Sensitive.
Select Digital Devices.
The Digital Devices page will allow you to configure all eight digital ports on the Hub. On Port 1 open the drop down menu and select Digital Device .
Note: Touch Sensors must always be configured on odd number ports.
Note: Touch Sensors can be configured as a REV Touch Sensor or a Digital Device. In the FTC SDK the type of device it is configured as changes the classes and methods that can be used.
Name the motor test_touch. Select done.
Note: remember when naming hardware in the configuration file that the REV Control System is Case Sensitive.
Select I2C Bus 0.
Select Add.
Note: Each I2C Bus can host more than one I2C sensor as long as the I2C addresses do not conflict. Bus 0 will always host the internal IMU. For more information on I2C sensors visit the I2C section.
On Port 1, which was created in the previous step, open the drop down menu and select REV Color Sensor V3.
Note: If you are using Color Sensors V1 or V2 select REV Color/Range Sensor. For more information on configuring with the REV Color Sensors visit the Color Sensor Datasheets.
Name the motor test_color. Select done.
Note: remember when naming hardware in the configuration file, that the REV Control System is Case Sensitive.
Hit Done twice until you reach the USB Devices in configuration page. On the USB Devices in configuration page hit Save.
Name the configuration helloRobotTest and then select Ok.
Note: The FTC SDK does not force you to abide by a naming convention for but it is common to name configurations in lowerCamelCase.
Press back to activate the saved configuration. Your Robot Controller will restart once you activate a new configuration.
