I2S Data rate

Nikolay Solovyev

Hi there!

I have a project using the eZdsp5515.

Goal: connect the external 16-Bit ADC chip with Frame-Sync protocol via I2S bus to digitize signals (sampling rate 50 MHz).

In this way: PLL freq = 120 MHz, I2S port is configured in Slave Mode, DMA is used to transfer, I2S_FS = 50 MHz, I2S_CLK = 50 MHz * 8 = 400 MHz (16-Bit Serialization).

Questions: 1) Is it possible to take data from ADC to main memory at this speed?

2) What maximum data rate can be achieved using I2S + DMA? (at least approximately)

Regards,

Nick

over 12 years ago

0 Steve Tsang over 12 years ago

TI__Mastermind 23785 points

The SAR ADC module can only operate at a maximum clock rate is 2 MHz and takes 32 clocks cycles to convert a value. This results in a maximum sample rate of 64 ksps.

0 Nikolay Solovyev over 12 years ago in reply to Steve Tsang

Prodigy 100 points

Hi, Steve!

Thank you for your response, but it seems you do not quite understand the point of my question.

I know the performance characteristics of the internal SAR ADC however internal ADC of the C5515 does not meet my performance needs. Thats why i need to expand the c5515 ezdsp USB stick with high speed (up to 50 MHz) ADC daughter card (using expand connector, I2S bus and DMA transfer to internal memory). So the both questions mentioned above are steel interesting for me.

viz. Questions: 1) Is it possible to take data from ADC to main memory at this speed?

2) What maximum data rate can be achieved using I2S + DMA? (at least approximately)

Regards,

Nick

0 Mark M over 12 years ago in reply to Nikolay Solovyev

TI__Mastermind 30140 points

Hi Nick,

I2S_CLK maximum is 25MHz in the C5515 datasheet @ DVDDIO 3.3V, 2.75V, 2.5V.

I2S_FS equals I2S_CLK divided by some power of 2, typically 16 - for a max I2S_FS of 1.5625 MHz, assuming 16 for example.

Look to C6000 for faster peripherals.

Hope this helps,
Mark

0 Nikolay Solovyev over 12 years ago in reply to Mark M

Prodigy 100 points

Thank you very much, Mark, you really helped!

Best regards,

Nick

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I2S Data rate