TMS320F280049: How to connect an ADC with SPI and multiple data lines

Hi Sebastian,

It does look that ADC can support single data line (with somewhat reduced throughput/latency) so if your application can support it you can try just using the SPI at the maximum clock rate (i believe 25MHz); that'll be much easier to implement.

Otherwise, I think you will need to use two SPI modules.  Say SPI-A as 'master' and SPI-B as 'slave'.  SPI A sends the CS to the ADC as well as a clock and receives data back from ADC SDOA.  SPI B would use the clock and chip select from SPI-A (similar to loopback) but actually take data into the data input line from the ADC SDOB pin.  

Module A:

• SPI-A: SIMO --> ADC SDI
• SPI-A: SOMI --> ADC SDOA
• SPI-A: CLK --> ADC SCLK and SPI-B CLK       
• SPI-A: STE (Chip select) --> ADC CS, SPI-B STE

Module B:

• SPI-B: SIMO --> ADC SDOB
• SPI-B: SOMI --> Don't care
• SPI-B: CLK --> from SPI-A CLK     
• SPI-B: STE (Chip select) --> from SPI-A STE

Depending on how fast you operate the interface, you may need to add some intentional delay to the clock going to SPI-B to better match the data coming out of the ADC.

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I'll also just go ahead and point out that C2000 does have microcontrollers with integrated 16-bit ADCs.  TMS320F28379D and TMS320F28379S families have up to 4 x 1.1MSPS fully differential 16-bit ADCs and TMS320F28388D and TMS320F28388S families have up to 4 x 1.1MSPS differential or single-ended 16-bit ADCs. 

I think this should be much easier to implement, much lower latency, and probably much lower cost vs using an external ADC.  You can simultaneously sample up to 4 inputs and the ADCs have additional muxed inputs if you need to sample additional signals.  The ADC you selected does have slightly higher SNR and wider common-mode range. 

Other engineers from TI can also probably recommend TI external ADCs that might meet your application requirements if you post in the data converters forum.