Capture samples(audio) from ADC interface and write to PWM ( is connected to speaker)

Hello Thiru,

Would it be possible to provide us more information about your hardware and software platforms?

Please take a look on information described in these links - processors.wiki.ti.com/.../Sitara_Linux_SDK_PWM
processors.wiki.ti.com/.../AM335x_PWM_Driver%27s_Guide

Best regards,
Yanko

Thanks for your response Yanko,

I'm using Beagle Bone block, I have connected Analog path to 12 bit ADC(mike is interfaced to it) , Needs to capture the samples from it into one buffer and then need to write to PWM which is connected to speaker.

i'm trying to write to sysfs entry

periodVal = (1/48000) * 1000000000 ; //in nanoseconds
//set duty cycle to zero before changing the period
duty = fopen("/sys/class/pwm/pwmchip0/pwm0/duty_cycle", "w");
fseek(duty,0,SEEK_SET);
fprintf(duty,"%d",0);
fflush(duty);

//set period of 48KHz
period = fopen("/sys/class/pwm/pwmchip0/pwm0/period", "w");
fseek(period,0,SEEK_SET);
fprintf(period,"%ld",periodVal);
fflush(period);

for(i=0;i<sample_count;i++)
{
fseek(duty,0,SEEK_SET);
fprintf(duty,"%d", dutyVal[i]); //dutyVal[] is the samples collected from ADC
fflush(duty);
}

The code snippet is correct ? if not please suggest correct way of doing

Regards,
Thiru N

Hello Thiru,

Your code seems correct. It seems you want to write a script for PWM audio, which will be executed from user space.

See the following similar project:
elinux.org/.../Pulse_Width_Modulation
github.com/.../omap3-pwm
learn.adafruit.com/.../setting-up-io-python-library-on-beaglebone-black.pdf
www.egr.msu.edu/.../meng.pdf

Best regards,
Yanko

Hi Yanko,

Thank you for your suggestion, I'm trying to use /sys entry only for writing to pwm from user space.

Regards

Thiru N