Teensy 3.2 I2S BCLK true value.

[roomtek]

Hello,

I am working on a radio project with the Teensy 3.2, and have successfully been able to connect my radio chip (Si4735) to the teensy via I2C and I am passing the audio to the Teensy via I2S, which is then routed over usb to a PC, using this config:

AudioInputI2S i2s1; //xy=286,208
AudioOutputUSB usb1; //xy=529,303
AudioConnection patchCord1(i2s1, 0, usb1, 0);
AudioConnection patchCord2(i2s1, 1, usb1, 1);


The Si4735 needs a clock source for tuning the radio, and allows me to choose the I2S clock as my reference clock along with a prescaler. On the documentation, I see this "LRCLK (44.1 kHz), BCLK (1.41 MHz)".

I need to know the actual full value of the BCLK clock. Does the 1.41 MHz stated mean an exact 1,410,000 Hz, and is this state somewhere I can look up. Thanks.

 

[WMXZ]

Hello,

I am working on a radio project with the Teensy 3.2, and have successfully been able to connect my radio chip (Si4735) to the teensy via I2C and I am passing the audio to the Teensy via I2S, which is then routed over usb to a PC, using this config:

AudioInputI2S i2s1; //xy=286,208
AudioOutputUSB usb1; //xy=529,303
AudioConnection patchCord1(i2s1, 0, usb1, 0);
AudioConnection patchCord2(i2s1, 1, usb1, 1);


The Si4735 needs a clock source for tuning the radio, and allows me to choose the I2S clock as my reference clock along with a prescaler. On the documentation, I see this "LRCLK (44.1 kHz), BCLK (1.41 MHz)".

I need to know the actual full value of the BCLK clock. Does the 1.41 MHz stated mean an exact 1,410,000 Hz, and is this state somewhere I can look up. Thanks.

in the file Audio/output_i2s.cpp
you find the line

// MCLK needs to be 48e6 / 1088 * 256 = 11.29411765 MHz -> 44.117647 kHz sample rate

The bitclock is mutliple of the sampling rate (32 bits per LR sample) so BCLK shlould be

BCLK = 48e6*256/1088/8 = 1411764.7059

 

[roomtek]

Thanks for the info!. It works as intended.