FTC 21430 "BroomBots" SystemCore Progress Thread

[FriendlyGuardian]

Our team received our SystemCore and MotionCore set at championships and started with our basic testing soon after returning. As of writing this we have completed task 1 for the hybrid configuration including SystemCore setup, WPILib installation, running the expansion hub test Op-Modes, and we also got PID controllers running with the motors and the expansion hub encoder ports. This process took us around three hours to complete when we did it on 5/9/2026. Here are some thoughts we had written down during that session:

• While it appeared that we could fully setup our SystemCore module on Linux, the Limelight Hardware Application needed to install the SystemCore firmware was not supported - We noticed that Linux support was mentioned as in progress in some places in the documentation, this was not a blocking action however we thought it would be nice to mention that Linux support would be helpful for some teams such as ours.
• We were quite confused attempting to get our SystemCore to boot into "flash mode", We thought that we needed to hold the button once it finished turning on, not as soon as power was provided to the hub.
• In our confusion as apart of the last note, we thought that perhaps we were supposed to be trying to power the SystemCore off of the USB Connection, and not off of ExpansionHub power.
• We attempted to start our testing in python, however the commands in the documentation were not working because it could not find the "robotpy" init module.
• We then changed approach and instead used java with the setup wizard.
• The rest of the process was quite straight forward
• Setting up PID control on the motor was also incredibly easy, because WPILib already has a PID Controller Class just like the one we programmed ourselves in previous seasons with the REV Control System.

We were wondering: where would we start in order to testing SystemCore's vision processing capabilities? Apologies if new resources or updates have released since then and we missed them.

Now that the team is returning to session after a break, we are ready to continue our testing and are eager to push the control system to its limits. Thanks!

[Kevin-OConnor]

The vision processing support has not been released yet. Limelight has been making a lot of progress on it and an initial release will hopefully be coming soon.

[FriendlyGuardian]

We started moving onto a301 testing, however we are running into an issue with the A301 firmware update from prerelease_4 to prerelease_12 via the Rev Hardware Client 2 (RHC2) lite on the SystemCore. We downloaded the firmware and the application from A301.md links, and it all worked as the documentation described until we needed to update the A301. When We push "install" on RHC2 with 12 loaded from the computer, the A301 screen refreshes back to how it was before, still on prerelease_4. Additionally, When attemping to "add the code a301-alpha to the Downloads tab, the channel has an error, and the browse button seemingly does nothing. We are currently blocked by this problem. Thanks!

[jfabellera]

This is a known issue with RHC2 (#276). You should be able to power cycle and try again and it will perform an update.

You won't be able to add the code if you're on Systemcore since it needs to be connected to the internet.

[FriendlyGuardian]

Thank you, We ran the power cycle it was able to get all of our A301 prototypes updated. We started with one and then did the next seven at once.

[gearsincorg]

How did you do the bulk update? I can't seem to find that option.

[FriendlyGuardian]

In RHC2, on the hardware tab, there was a button labeled "Update Manager". From that menu I selected "A301" in the drop down, and then it brought up a list of all of the A301s connected to the MotionCore with check boxes next to them. I clicked select all, uploaded the A301 Firmware prerelease 12 as shown in the image in the A301.md file, and then clicked "Install", which did the update to all 7 at once.

[gearsincorg]

Thanks. Even knowing it was there, I still nearly missed it. Not sure why it's all the way over at the right like that.

[FriendlyGuardian]

Current status update, No major accomplishments since last post.

Current Goal
I started by trying to control two A301s using the method from the expansionhub example code that feeds the joystick y value on the controller into the power on the motor.

Progress
Currently that does not do anything when I run the opmode. I then tested the A301s using the run utility in RHC2 on SystemCore to check if the motors can run at all: which they can. To continue to debug these, I started trying to figure out how to view telemetry out of the code with the intent to have it read values from the joysticks and the A301's current and throttle.

NEW QUESTION: HOW DO WE DO TELEMETRY???

What I did
Starting down this side journey, I figured out how to get the 2027 alpha of AdvantageScope working on the same windows laptop I have been using for the FIRST Driver Station app. Then to connect to SystemCore, I had to refer to the Advantage Scope documentation for a while to realize that the "connect to robot" button was under the file tab. After another long while of trying to figure out why it was stuck searching, I ended up googling it and it said I needed to configure the target IP Address. I had thought it would be configured already because the connect button had "(systemcore)" next to it. I found the IP in the SystemCore wifi configuration screen. 172.30.0.1 I had to click around for a while to find where to change that, found it under App/Show Preferences. Then it connected 🎉 I then had access to all of the data from the SystemCore like the voltage and IMU values.

Next came getting a value up onto AdvantageScope. I tried refering to the WPILib Documentation for Telemetry where I originally learned about AdvantageScope, but nowhere did I find an example of how to actually log the data to be seen. Another google search / minor AI assist got me to the DataLogManager class in WPILib, alongside DataLog. By reading the source code for those classes, I think I figured out how to do it for just one joystick value. (I in fact did not)

Current State + Blocking Issues

I have Advantage Scope connected to SystemCore telemetry such as imu data and all the diagnostics are displayed.

My 'DefaultTeleMode' does nothing which the joysticks are moved with 2 A301s connected to MotionCore ports D0 and D1.

My joystick telemetry does not appear anywhere in AdvantageScope when the opmode is running, and I decided I needed to log my session and take a break. If anyone is familiar with these things, I would really love some help!

Project Code

Robot.java

// Copyright (c) FIRST and other WPILib contributors.
// Open Source Software; you can modify and/or share it under the terms of
// the WPILib BSD license file in the root directory of this project.

package first.robot;

import org.wpilib.driverstation.DefaultUserControls;
import org.wpilib.driverstation.UserControlsInstance;
import org.wpilib.framework.OpModeRobot;
import org.wpilib.hardware.expansionhub.ExpansionHubMotor;
import org.wpilib.hardware.expansionhub.ExpansionHubServo;

import com.revrobotics.spark.A301;

/**
 * This is a demo program showing the use of the Expansion Hub motors and servos. The motors and
 * servos are driven using the controllers in the telop opmode, and timed in the auto op mode.
 */
@UserControlsInstance(DefaultUserControls.class)
public class Robot extends OpModeRobot {
  public final A301 motor1 = new A301(0);
  public final A301 motor2 = new A301(1);
  
  /** Called once at the beginning of the robot program. - INIT */
  public Robot() {}
}

DefaultTeleMode.java

// Copyright (c) FIRST and other WPILib contributors.
// Open Source Software; you can modify and/or share it under the terms of
// the WPILib BSD license file in the root directory of this project.

package first.robot;

import java.util.logging.Logger;

import org.wpilib.driverstation.DefaultUserControls;
import org.wpilib.opmode.PeriodicOpMode;
import org.wpilib.opmode.Teleop;
import org.wpilib.system.DataLogManager;
import org.wpilib.datalog.*;

@Teleop
public class DefaultTeleMode extends PeriodicOpMode {
  private final Robot robot;
  private final DefaultUserControls userControls;
  private DoubleLogEntry joyStickLog;

  public DefaultTeleMode(Robot robot, DefaultUserControls userControls) {
    this.robot = robot;
    this.userControls = userControls;
    DataLogManager.start();
    DataLog log = DataLogManager.getLog();
    joyStickLog = new DoubleLogEntry(log, "/joy/double");
  }

  @Override
  public void periodic() {
    robot.motor1.setThrottle(userControls.getGamepad(0).getLeftY());
    robot.motor2.setAbsolutePosition(userControls.getGamepad(0).getRightY(), false);
    joyStickLog.append(userControls.getGamepad(0).getLeftY());
    }
}

[Gold856]

If you use DataLogTool, you should be able to download the logs off Systemcore and open them up in AdvantageScope. The mode you connected with is actually for the internal NT server that interfaces all the I/O, and has since been renamed "Systemcore Diagnostics" to reduce confusion. For live telemetry, we are working on a new Telemetry API, but for now, the SmartDashboard class is the recommended way to do simple telemetry.

[gearsincorg]

The CAN Id's you have for your motors are not correct:

You have:
public final A301 motor1 = new A301(0);
public final A301 motor2 = new A301(1);

Ports 0 and 1 are actually on the Systemcore. For the motion core, you want to use these constants:

CANBusMap.CAN_D0
CANBusMap.CAN_D1

Which actually translate to 5 and 6.
0-4 are on the SystemCore.

Note: you also MUST update the firmware on the A301's otherwise you code will crash because the firmware they ship with is outdated.

[FriendlyGuardian]

Thank you! That makes far more sense. A301s are now running great!

[FriendlyGuardian]

A Quick suggestion to improve the clarity of the A301 class construction.
The Current Constructor

public A301(int busId) 

My Suggestion

public A301(CANBusMap busId)

Team Code

public A301 motor = new A301(CANBusMap.CAN_D0);

This way there is no way that a team could pass an integer in the wrong format like I had.

[zachwaffle4]

public A301 motor = new A301(CANBusMap.CAN_D0);

In current WPILib, because the CANBusMap constants are integers, this is possible (and recommended). Future versions of WPILib replace the integer constants with enum constants, and we expect REVLib to similarly replace their constructor accepting an integer with one accepting a CANBus constant.

[FriendlyGuardian]

One piece of hardware feedback we have is that the powerswitch should be a seperate component from the battery dock. Given that the battery is a large source of the weight for the robot, teams including us move the battery to the bottom on the robot or use it to shift the center of mass, therefore making the battery an invalid place for the powerswitch.

[FriendlyGuardian]

We would like to request hex shaft options for the A301 including 8mm for GoBilda and 5mm for Rev. This will make the A301s compatible with FTC teams' existing parts, as there are currently no spline shafts in common FTC Kits.

[sfe-SparkFro]

We did a drop test to compare the durability and repairability of hex and spline shafts. We used 3 inch segments of an 8mm hex shaft (goBILDA) and the provided spline shaft, dropped from 5ft onto cement shop floor.

Although both sustained minor damage, the hex shaft is very easy to clean up with a file. The spline shaft is more difficult, especially since the burr was in the middle. This caused the spline shaft to jam in the A301 until we could shave it down.

[sfe-SparkFro]

Me personally, not on behalf of any team or anyone else - I think it's great for spline shafts being added as a new option for teams, however I don't think it's fair to force it upon everyone. I've volunteered as an FTA for years now, and I've never seen an FTC team using spline shafts, the vast majority of teams use hex shafts. They're more than sufficient for all FTC use cases, I don't see a good argument for forcing teams to buy and build more bulky adapters when hex shafts could easily be natively supported.

[FriendlyGuardian]

Having the ability to run the A301 without the full SystemCore & MotionCore setup would improve the prototyping process. Our hardware team made handheld switches that connect a battery directly to legacy FTC motors, where the students only need to click the switch one way or another. Servo Testers such as this one https://a.co/d/0gaxjhqe (Amazon Link) are also used. A separate device that can interface with the A301 would help teams experiment.