ESP8266 Community Forum

- Sun Jun 21, 2015 3:13 am #21082

I'm impressed, the sound quality is actually very acceptable!

At what frequency does the pwm run then?

Not classic PWM -> http://www.beis.de/Elektronik/DeltaSigm ... Sigma.html
Output: 2xInegrator: https://github.com/pvvx/mp3_decode/blob ... main.c#L75
Log sample: Rate 48000 x 32 bits.

Thx. I guess you you mean you compensate the lack of duty cycle resolution with more oversampling?

- Sun Jun 21, 2015 3:15 am #21083

I'd expect rather poor sound quality though, as the pwm duty has only 8 bits resolution?

PWM_HACK = PWM 5 bits

Its reported elsewhere that it is 10 bit resolution?

Yes, from SDK 1.1.1 PWM seems to be "upgraded" to 10 bits resolution.

That's a lot better, but my simple atmega328p still beats it at large with 16 bits PWM!

- Sun Jun 21, 2015 4:32 am #21084 @sprite_tm or @pvvx i am getting this and i am hearing just noise not music, any help?i defined pwm_hack

Code: Select allConnecting to server 188.40.123.50...
Reading into SPI RAM FIFO...
MAD: Decoder start.
dec err 0x0101 (lost synchronization)
Rate 22050
Buffer fill 21908, DMA underrun ct 0, buff underrun ct 0
Buffer fill 21893, DMA underrun ct 0, buff underrun ct 0

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Lets get the party started and +1

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I like ESP8266 and ESP8285 and ESP32

- Sun Jun 21, 2015 12:25 pm #21115

@sprite_tm or @pvvx i am getting this and i am hearing just noise not music, any help?i defined pwm_hack

Code: Select allConnecting to server 188.40.123.50...
Reading into SPI RAM FIFO...
MAD: Decoder start.
dec err 0x0101 (lost synchronization)
Rate 22050
Buffer fill 21908, DMA underrun ct 0, buff underrun ct 0
Buffer fill 21893, DMA underrun ct 0, buff underrun ct 0

I had a similar problem. What output pin are you using? GPIO3 (RXD) is the correct one.
Rgds

Horacio