Class Telemetry

java.lang.Object

frc.spectrumLib.telemetry.Telemetry

public class Telemetry
extends Object

Telemetry and logging facade, backed by AdvantageKit.

In 2026 this class extended DogLog. On SystemCore it keeps the same static API (log, logDash, logDashAlways, print, time/timeEnd, slowLogThisLoop), so every existing call site compiles unchanged. Every value is now an AdvantageKit output (Logger.recordOutput(String, byte[])). Outputs land in the same wpilog as the replayed inputs, under /RealOutputs/... on the robot and /ReplayOutputs/... in replay, so a replayed match regenerates every one of these keys from the code under test.

Rules that come with AdvantageKit

• Main thread only. Logger is not thread-safe. Nothing on a Notifier, the CTRE odometry thread or a vision callback may call this class; hand the data to the main loop and log it there (see Swerve's odometry queue).
• Outputs never drive logic. Anything a decision depends on must come from a logged input (Logger.processInputs(String, LoggableInputs)), or replay will diverge.

Tiers

• log(String, double) records to the log only.
• logDash(String, double) / logDashAlways(String, double) record to the log and mark the key as a dashboard key, which DashboardReceiver also sends to NetworkTables. Only dashboard keys (these, and every key the Elastic layout reads) go to NT, unless the "/SmartDashboard/Telemetry/MirrorLogsToNT" switch is on. That is the 2026 offseason rule, for the CPU it costs.
• slowLogThisLoop() is true at 10 Hz whatever the loop rate. Wrap logs that do not need loop-rate resolution (currents, temperatures, vision status) in it.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static enum	Telemetry.Fault	Named fault conditions that can be surfaced as structured log entries.
static enum	Telemetry.PrintPriority	Priority levels for printing to the console.

Field Summary

Fields

Modifier and Type	Field	Description
static final String	NT_MIRROR_SWITCH_KEY	Dashboard key of the switch that mirrors every log entry to NetworkTables.
static final double	SLOW_LOG_PERIOD_SECONDS	Seconds between slow-tier publishes (10 Hz at any loop rate).

Method Summary

Modifier and Type	Method	Description
static void	addDashboardKey(String key)	Marks a key for NetworkTables, e.g.
static int	addDashboardKeysFromElasticLayout(String layoutJson)	Marks every output the Elastic layout reads as a dashboard key, so what Elastic shows is exactly what goes over NetworkTables and the two cannot drift apart.
static boolean	isDashboardKey(String key)	Whether an output key (relative to the outputs table) is a dashboard key.
static boolean	isDashboardTableKey(String tableKey)	Whether an absolute log-table key (/RealOutputs/<key>) is a dashboard key.
static boolean	isMirroringAll()	Whether every output is being mirrored to NetworkTables right now.
static void	log(String key, boolean value)
static void	log(String key, boolean[] value)
static void	log(String key, double value)
static void	log(String key, double[] value)
static void	log(String key, double value, String unit)
static void	log(String key, float value)
static void	log(String key, int value)
static void	log(String key, int[] value)
static void	log(String key, long value)
static void	log(String key, long[] value)
static <E extends Enum<E>> void	log(String key, E value)
static void	log(String key, String value)
static void	log(String key, String[] value)
static <U extends Unit> void	log(String key, Measure<U> value)
static <T extends WPISerializable> void	log(String key, T value)
static <T extends StructSerializable> void	log(String key, T... value)
static Command	log(Command cmd)	Wraps a command so that its initialization and end are logged to the "Commands" key.
static void	logDash(String key, boolean value)
static void	logDash(String key, double value)
static void	logDash(String key, double value, String unit)
static void	logDash(String key, long value)
static void	logDash(String key, String value)
static void	logDashAlways(String key, boolean value)
static void	logDashAlways(String key, double value)
static void	logDashAlways(String key, double value, String unit)
static void	logDashAlways(String key, long value)
static void	logDashAlways(String key, String value)
static void	logEvent(String key, String message)	Logs a discrete event.
static void	periodic()	Updates the mirror switch.
static void	print(String output)	Prints a message at Telemetry.PrintPriority.NORMAL priority.
static void	print(String output, Telemetry.PrintPriority priority)	Print a statement if the priority allows it.
static boolean	slowLogThisLoop()	Returns true on the loops the slow telemetry tier publishes on.
static void	start(Telemetry.PrintPriority priority)	Sets the console print priority.
static void	startDashboard(boolean mirrorByDefault)	Creates the mirror switch.
static void	time(String key)	Starts a timed span.
static void	timeEnd(String key)	Ends a timed span and logs its length in seconds, so existing analysis of the Scheduler/* keys keeps working.

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

SLOW_LOG_PERIOD_SECONDS

public static final double SLOW_LOG_PERIOD_SECONDS

Seconds between slow-tier publishes (10 Hz at any loop rate).

See Also:

• Constant Field Values

NT_MIRROR_SWITCH_KEY

public static final String NT_MIRROR_SWITCH_KEY

Dashboard key of the switch that mirrors every log entry to NetworkTables. Forced off when the FMS is attached.

See Also:

• Constant Field Values

Method Details

slowLogThisLoop

public static boolean slowLogThisLoop()

Returns true on the loops the slow telemetry tier publishes on. Every caller in the same loop agrees, so related values are logged in the same cycle.

Returns:

whether slow-tier values should be logged this loop

start

public static void start(Telemetry.PrintPriority priority)

Sets the console print priority. Data receivers and the replay source are configured in Robot before Logger.start(), not here.

Parameters:

priority - The minimum priority level for console output.

log

public static void log(String key,
 double value)

log

public static void log(String key,
 double value,
 String unit)

log

public static void log(String key,
 float value)

log

public static void log(String key,
 boolean value)

log

public static void log(String key,
 int value)

log

public static void log(String key,
 long value)

log

public static void log(String key,
 String value)

log

public static void log(String key,
 double[] value)

log

public static void log(String key,
 boolean[] value)

log

public static void log(String key,
 long[] value)

log

public static void log(String key,
 int[] value)

log

public static void log(String key,
 String[] value)

log

public static <E extends Enum<E>> void log(String key,
 E value)

log

public static <T extends WPISerializable> void log(String key,
 T value)

log

@SafeVarargs
public static <T extends StructSerializable> void log(String key,
 T... value)

log

public static <U extends Unit> void log(String key,
 Measure<U> value)

startDashboard

public static void startDashboard(boolean mirrorByDefault)

Creates the mirror switch. Call once, after the logger has started.

Parameters:

mirrorByDefault - initial position: on in simulation, off on the robot

periodic

public static void periodic()

Updates the mirror switch. Call once per loop.

isMirroringAll

public static boolean isMirroringAll()

Whether every output is being mirrored to NetworkTables right now.

isDashboardKey

public static boolean isDashboardKey(String key)

Whether an output key (relative to the outputs table) is a dashboard key.

isDashboardTableKey

public static boolean isDashboardTableKey(String tableKey)

Whether an absolute log-table key (/RealOutputs/<key>) is a dashboard key. For the NetworkTables receiver, which walks the whole table every cycle: one hash lookup per entry, no substring.

addDashboardKey

public static void addDashboardKey(String key)

Marks a key for NetworkTables, e.g. one a dashboard layout reads.

addDashboardKeysFromElasticLayout

public static int addDashboardKeysFromElasticLayout(String layoutJson)

Marks every output the Elastic layout reads as a dashboard key, so what Elastic shows is exactly what goes over NetworkTables and the two cannot drift apart. Topics under /AdvantageKit/RealOutputs/ become output keys.

Parameters:

layoutJson - the layout file's contents

Returns:

how many keys were added

logDash

public static void logDash(String key,
 double value)

logDash

public static void logDash(String key,
 double value,
 String unit)

logDash

public static void logDash(String key,
 boolean value)

logDash

public static void logDash(String key,
 String value)

logDash

public static void logDash(String key,
 long value)

logDashAlways

public static void logDashAlways(String key,
 double value)

logDashAlways

public static void logDashAlways(String key,
 double value,
 String unit)

logDashAlways

public static void logDashAlways(String key,
 boolean value)

logDashAlways

public static void logDashAlways(String key,
 String value)

logDashAlways

public static void logDashAlways(String key,
 long value)

time

public static void time(String key)

Starts a timed span. Pair with timeEnd(String) on the same key.

Uses the real clock, not Logger.getTimestamp(), because the point is to measure how long the code took. In replay these values describe the replay machine, not the robot.

Parameters:

key - the log key the elapsed time will be written to

timeEnd

public static void timeEnd(String key)

Ends a timed span and logs its length in seconds, so existing analysis of the Scheduler/* keys keeps working.

Parameters:

key - the key passed to time(String)

logEvent

public static void logEvent(String key,
 String message)

Logs a discrete event. AdvantageKit keeps one value per key per cycle. Logging two messages to the same key in one loop kept only the second, so two commands ending in the same loop, or two prints, lost one. Events are accumulated per loop and recorded as a string array holding all of them.

Parameters:

key - the log key

message - the event

log

public static Command log(Command cmd)

Wraps a command so that its initialization and end are logged to the "Commands" key.

Parameters:

cmd - The command to wrap

Returns:

a decorated command that logs lifecycle events and preserves the original name

print

public static void print(String output,
 Telemetry.PrintPriority priority)

Print a statement if the priority allows it. AdvantageKit captures the console into the log, so the text is also recorded; it is additionally logged under "Prints" for search.

print

public static void print(String output)

Prints a message at Telemetry.PrintPriority.NORMAL priority.

Parameters:

output - The string to print