I need to acquire data from a 16 bit parallel ADC card at 250K samples/sec and stream to an SD card. The ADC card is driven by an external oscillator. I have currently running an Arduino Due, which is driven by interrupts from the ADC board. The Due fills its memory then writes the data to an SD card on an Adafruit data logging shield. The Due fails if I try to write to the SD card while recording.

This is acceptable, but not ideal, because I am interested in the spectrum of the input, rather than a continuous recording.* I would like to replace the Due with the teensy 4.1.

Question: What is happening with the 4.1 processor during a write to the internal SD card?

1. Will an interrupt during the WRITE disrupt the process?
2. If, instead of using an interrupt, I poll the ADC board, how long will the processor be unavailable? (Less than 4 uSec?)


*The original motivation was insight into what my dog is hearing: She hears frequencies above 50 kHz. The transducer is a Knowles MEMS microphone relatively flat past 80 kHz.