As I was searching online trying to learn how to use RobotC I found a very helpful website that describes many commands for both the NXT and RXC. I went through it deleted the parts about the RXC, and went through every single step and downloaded the programs on the NXT. This was very helpful and very time consuming but you end up with a great deal of knowledge once you are done with all of it. You could also find this on the RobotC website at http://www.robotc.net/content/lego_quick/media/code_listing/nxt.html .
Motors
Basic motor control commands, plus some fine-tuning commands.
| NXT |
Turn the referenced NXT motor output either on or off and also sets the power level of the motor outputs.
The NXT has 3 motor outputs: motorA, motorB, motorC
The NXT can handle power levels from -100 (full reverse) to 100 (full forward). A power level of 0 will cause the motors to stop.
motor[motorA] = 100; //Output A - full speed forward
motor[motorB] = 100; //Output B - full speed forward
| NXT |
This feature is used to reverse the direction the referenced motor travels. Once this setting is changed, the reference motor will be reversed for the entire program (unless manually changed a later point in the program)
This is useful for when working with motors that mounted in different directions and the programmer wants to keep the power setting the same for both motors.
There are two settings: 0 - normal, 1 - reversed
Before:
motor[motorA] = -100; //Output A - full speed reverse
motor[motorB] = 100; //Output B - full speed forward
After:
bMotorFlippedMode[motorA] = 1; //Motor Direction Flipped
motor[motorA] = 100; //Output A - full speed reverse
motor[motorB] = 100; //Output B - full speed forward
| NXT |
This switch is used to choose wether the motors on the NXT will float or brake when there is no power applied. By default, the motors will float.
The reason to switch this is if you're trying to make precise turns with the NXT and the motors are drifting causing the change in direction to be off.
There are two settings for this switch:
false - motors will brake when inactive
true - motors will float when inactive
bFloatDuringInactiveMotorPWM = false; //motors will brake when power is set to "0"
Timers
The NXT allows you to use Wait commands to place delays in your program. It also supports Timers, which work like stopwatches - they count time since the last reset, and you reset them again when you want to start or restart.
| NXT |
This function will cause a program to wait a specified number of milliseconds before executing the next instruction in a program.
Wait_time is an integer (1 = 1/1000th of a second). Maximum wait time is 32.768 seconds when using this function.
motor[motorA] = 100; //Output A - full speed forward
wait1Msec(2000); //Wait 2 seconds
motor[motorA] = 0; //Output A - off
| NXT |
This function will cause a program to wait a specified number of hundredths of a second before executing the next instruction in a program.
Wait_time is an integer (1 = 1/100th of a second). Maximum wait time is 327.68 seconds when using this function.
motor[motorA] = 100; //Output A - full speed forward
wait10Msec(200); //Wait 2 seconds
motor[motorA] = 0; //Output A - off
| NXT |
This timer function returns the current value of the referenced timer as an integer in a specific resolution. The resolution for "time10" is in milliseconds (1 = 1/1000th of a second).
The maximum amount of time to be recorded is 32.768 seconds (~1/2 minute)
The NXT has 4 internal timers: T1, T2, T3, T4
int x; //Init variable x
x = time1[T1]; //assign variable x value of Timer #1 (1/1000th seconds)
| NXT |
This timer function returns the current value of the referenced timer as an integer in a specific resolution. The resolution for "time10" is in hundredths of a second (1 = 1/100th of a second).
The maximum amount of time to be recorded is 327.68 seconds (~5 minutes)
The NXT has 4 internal timers: T1, T2, T3, T4
int x; //Init variable x
x = time10[T1]; //assign variable x value of Timer #1 (1/100th seconds)
| NXT |
This timer function returns the current value of the referenced timer as an integer in a specific resolution. The resolution for "time100" is in tenths of a second (1 = 1/10th of a second).
The maximum amount of time to be recorded is 3276.8 seconds (~54 minutes)
The NXT has 4 internal timers: T1, T2, T3, T4
int x; //Init variable x
x = time100[T1]; //assign variable x value of Timer #1 (1/10th seconds)
| NXT |
Resets the referenced timer back to zero seconds.
The NXT has 4 internal timers: T1, T2, T3, T4
ClearTimer(T1); //Clear Timer #1
Sensors
Sensor commands for configuration and usage are listed below. Most sensor setup should be done through the Robot > Motors and Sensors Setup menu for best results.
| NXT |
| Sensor Type | Description | Range of Values |
| sensorTouch | Digital | 0 to 1 |
| sensorLightActive | Analog, Percentage | 0 to 100 |
| sensorLightInactive | Analog, Percentage | 0 to 100 |
| sensorSoundDB | Analog, Percentage | 0 to 100 |
| sensorSONAR | Distance, CM | 0 to 255 |
This function is used to manually set the mode of a specific input port to a specific type of sensor. We recommend, however, that you use the "Motor and Sensors Setup" wizard in RobotC.
The NXT has 4 sensor inputs: S1, S2, S3, S4
The NXT supports 8 different types of sensors:
SetSensorType(S1, sensorTouch); //Input 1 now is set to be a Touch Sensor
| NXT |
SensorValue is used to read the value of the referenced sensor port. Values will correspond to the type of sensor set for that port (see set_sensor_type page).
The SensorValue function can be accessed like a variable, as it returns an integer value.
The NXT has 3 sensor inputs: S1, S2, S3, S4
SetSensorType(S1, sensorTouch); //Input 1 now is set to be a Touch Sensor
if(SensorValue(S1) == 1)
{
motor[motorA] = 100; //Output A - full speed forward
}
| NXT |
This function is used to access the internal encoder from the NXT's motors.
A value is return with the number of degrees the motor has traveled (1 = 1 degree), with the value as an integer.
while(nMotorEncoder[motorA] <>
{
motor[motorA] = 100; //Output A - full speed forward
motor[motorB] = 100; //Output B - full speed forward
}
You can also assign the value of nMotorEncoder to 0 to reset the encoder.
To reset the encoder on MotorA, use the following code:
nMotorEncoder[MotorA] = 0;
| NXT |
This function is used to reset the value of the referenced sensor port back to zero. This is only neccessary with specific sensor types that retain their values (e.g. Encoder Sensor).
The NXT has 4 sensor inputs: S1, S2, S3, S4
SetSensorType(S1, sensorRotation); //Input #1 now is set to be a Rotation Sensor
ClearSensorValue(S1); //Reset Input #1 back to a value of 0
Sounds
The NXT can generate tones, or play back stored waveform sound data.
| NXT |
Plays a sound from the NXT internal speaker at a specific frequency (1 = 1 hertz) for a specific length (1 = 1/100th of a second).
PlayTone(220, 500); //Plays a 220hz tone for 1/2 second
| NXT |
| Sound Names |
| soundBlip |
| soundBeepBeep |
| soundDownwardTones |
| soundUpwardTones |
| soundLowBuzz |
| soundFastUpwardTones |
| soundShortBlip |
| soundException |
Plays a sound effect from the NXT internal library. Requires a sound name to be passed to play the sound.
PlaySound(soundUpwardTones); //Plays the sound "Upward Tones"
| NXT |
This function is used to play a sound file that is on the NXT. NXT sounds files have the extension .rso.
PlaySoundFile(Whoops.rso); //Plays the sound file "Woops.rso"
LCD Display
Commands for the NXT's LCD Display.
| NXT |
Displays a text line on the LCD screen of the NXT. Up to three variables are passable to the function.
line_number - The line the text line will appear on the NXT. There are 8 lines of text avaiable to the users, and valid arguments for this parameter are 0-7, which correspond to lines 1-8 on thte NXT's screen.
text - The text parameter is what shows up on the screen. This will be a string enclosed in quotes up to 16 characters. You may also display variables with this parameter by using the "%d" to display a variable definined in later parameters. You may use up to 3 "%d" characters to display 3 seperate variables. Remeber that you can only display 16 total characters, so the value of the variables will take up some of those 16 characters.
var1, var2, var3 = These parameters define which variables will be displayed to the screen.
int x = 1; //declare first variable
int y = 2; //declare second variable
int z = 3; //declare third variable
nxtDisplayTextLine(0,"Test %d %d %d",x,y,z);
//layout to display the text "Test 1 2 3" on the first line of the NXT screen
| NXT |
Clears the NXT's LCD screen of all text and GUI images.
eraseDisplay();
Miscellaneous
Miscellaneous useful commands that are not part of the standard C language.
| NXT |
Returns a random number (integer) between 0 and the 'value' of the function.
int x; //declares x as an integer
x = random(100); //Returns a random value between 0 and 100
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