/********************************** Main routine ************************************/
void main()
{
// initialize board and the audio port
init_hardware();
sine_init();
// Loop endlessley generating a sine wave
while(1)
{
// Calculate next sample
sample = sinegen();
/* Send a sample to the audio port if it is ready to transmit.
Note: DSK6713_AIC23_write() returns false if the port if is not ready */
// send to LEFT channel (poll until ready)
while (!DSK6713_AIC23_write(H_Codec, ((Int32)(sample * L_Gain))))
{};
// send same sample to RIGHT channel (poll until ready)
while (!DSK6713_AIC23_write(H_Codec, ((Int32)(sample * R_Gain))))
{};
// Set the sampling frequency. This function updates the frequency only if it
// has changed. Frequency set must be one of the supported sampling freq.
set_samp_freq(&sampling_freq, Config, &H_Codec);
}
}
void ISR_AIC(void)
{
/*
* Since we have to write a 16 bit value, we cast to `short`, since there is no half
* precision floating point number type in C. However, since our sample will be between
* -1 and 1, casting to a short would mean we would only ever get the values 0, 1 and
* -1. So, we scale the value up by 2^15-1 (since 2^15 would cause overflow and
* incorrect output) before casting to ensure we don't lose information in the cast.
*/
float shifted_sample = sinegen()*32767;
sample = (short)fabs(shifted_sample);
mono_write_16Bit(sample);
}
