iMX8MN FlexSPI for ADC input

[evancornell]

Can iMX8MN (specifically MIMX8MN5DVPIZAA i.MX 8M Nano UltraLite Quad) FlexSPI peripheral be used to acquire data from LTC2315-12 high speed ADC? The eCSPI seems to have a maximum read clock frequency of 1/43ns = 23.2 MHz, which isn't enough to clock out the data from ADC. But FlexSPI can do 66 MHz, which should be fast enough. 

Also, can FlexSPI be made to have synchronous clock with SAI audio module? I need to run SAI at fs = 768 kHz (4 data lines, 8 channels), so SAI_MCLK ought to run at 49.152 MHz (768 kHz * 64 bits), and I'd like the FlexSPI to run at a related clock frequency to SAI peripheral.

Thanks!

[evancornell · Accepted solution]

Hello, wondering if anyone at NXP can help with the above question.. thanks!

[brian14]

Hi @evancornell,

Please accept my apologies for the delayed reply.

For the first question the FlexSPI interface for iMX8M Mini can achieve 66MHz is enough to collect the ADC data. However, I'm not sure if your ADC LTC2315-12 has an appropriate SPI interface.

"The LT2315-12 communicates with microcontrollers, DSPs, and other external circuitry via a 3-wire interface. A falling CS edge starts a conversion and frames the serial data transfer. SCK provides the conversion clock for the current sample and controls the data readout on the SDO pin of the previous sample."

You can try interfacing this ADC with the iMX setting up registers for the timing requirements of your ADC.

Regarding the second question, you will need to analyze the clock tree on iMX8M Mini Reference Manual section 5.1.3 Clock Tree and then configure the PLL using this manual.

If you have any questions or concerns, don’t hesitate to let me know.

Have a great day.

Best regards, Brian.