VEX2 Functions Sound

Main → CORTEX → Functions and Variables → Sound

ROBOTC provides a comprehensive suite of functions for controlling an optional speaker connected to the first motor port on a VEX controller. The ROBOTC firmware queues up to 10 sound items for playback. This allows user programs to initiate playback of a sound item and continue execution without having to wait for a sound item to finish; this mode of operation is very desirable for robots where, if you waited for the sound to complete playback, you could be delayed in updating the robot’s motors in reaction to a change in sensors. There are several sample programs illustrating sound playback on a VEX controller. The file “songs.c” contains several complete songs that can be played as a background task while your robot continues to execute its main “mission” task.

Color Key Function: Variable:

bPlaySounds

word bPlaySounds

(word) Boolean flag. Indicates whether new sound requests should be accepted or discarded. Note that this is defined as a word but is treated as a bool.

bPlaySounds = true; // ACCEPT new sound requests bPlaySounds = false; // DISCARD new sound requests

bSoundActive

const bool bSoundActive

(bool) Boolean flag. If true indicates sound system is actively playing sound.

while(bSoundActive) // while a sound is actively playing: { // do not continue until finished playing sound }

bSoundQueueAvailable

const bool bSoundQueueAvailable

(bool) Boolean flag. Indicates whether there is space available in the sound queue for another item.

if(bSoundQueueAvailable) // if there is still space in the Sound Queue: { PlayImmediateTone(SensorValue[lightSensor] * 80, 50); // play tone according to light sensor readings }

ClearSounds

void ClearSounds()

(void) Clears all existing and buffered sound commands.

ClearSounds(); // clear the sound buffer

MuteSound

void MuteSound()

(void) Mutes all subsequent sound commands.

MuteSound(); // MUTE

nVolume

word nVolume

(word) Sound volume. Range 0 to 4 (loudest).

nVolume = 1; // set the volume to 1, a nice and comfortable volume for a quiet location

PlayImmediateTone

void PlayImmediateTone(const int frequency, const int durationIn10MsecTicks)

(void) Immediately play tone at frequency & duration ahead of queued requests.

Parameter Explanation Data Type frequency The frequency of the tone to play int durationIn10MsecTicks How long to play the tone (measured in units of 10 milliseconds) int

while(true) { PlayImmediateTone(SensorValue[lightSensor] * 80, 50); // play tone according to light sensor readings wait1Msec(200); // wait 200 milliseconds before checking again }

PlaySound

void PlaySound(TSounds sound)

(void) Play one of the system predefined sounds (buzz, beep, click, ...)

Parameter Explanation Data Type sound A predefined system sound TSounds Predefined Sounds: soundBlip soundBeepBeep soundDownwardTones soundUpwardTones soundLowBuzz soundFastUpwardTones soundShortBlip soundException soundLowBuzzShort

PlaySound(soundBeepBeep); // play the sound, 'soundBeepBeep'

PlayTone

void PlayTone(const int frequency, const int durationIn10MsecTicks)

(void) Plays a constant tone at the specified frequency and duration.

Parameter Explanation Data Type frequency The frequency of the tone to play int durationIn10MsecTicks How long to play the tone (measured in units of 10 milliseconds) int

PlayTone(784, 15); // play a tone at a frequency of 784 for 150 milliseconds

UnmuteSound

void UnmuteSound()

(void) Restores sound playback volume.

UnmuteSound(); // UN-MUTE