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Altera_Forum's avatar
Altera_Forum
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16 years ago

SPI to I2S upgrade to 24 bit

Hi, I am currently working on a USB audio signal capture and playback device. I've noticed that all of the audio quality ADC/DACs use I2S to communicate but unfortunately my usb interfacing chi...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
16 years ago

There is another problem, that isn't directly related to SPI versus I2S interface. Digital audio chips usually require a fixed serial clock rate, that is directly locked to the system clock respectively sampling frequency. When using an asynchronous SPI master as the FTDI device, you need an elastic buffer with handshake bits to adapt the data rates. The FTDI side must have be able to achieve the required data rate plus an extra for handshaking.

So using a CPLD may be necessary to meet this requirement.