I'm evaluating the nRF52840 for a new project.
I have read a number of previous posts that show that I can't achieve what I want, but I want to be sure as the 840 is ideal for our application aside from this limitation.
My problem is that I need to acquire 2-5ms of data from a sensor with a 3 bit parallel interface clocked at 16.384Mhz (around ~32kilobytes of data with 3bits of data stored per byte of RAM).
I'm not concerned about the power usage during capture, so I don't require easyDMA or power saving features at this point.
1) I'm not sure that the GPIO peripheral on the 840 has the ability to be externally clocked, and as I can't find any reference in the datasheet I'm assuming it can't be. Can I clock the entire 840 with a 16.384Mhz or 32.768Mhz clock during the acquisition process ( from what I understand the RCC subsystem seems to only use a 32Mhz crystal).
2) If the QSPI peripheral was more flexible that would be perfect, but without a true QSPI interface on the sensor, don't think it is possible. Should I investigate further?
3) The data rate isn't adjustable, but if I have to, I can read only 1 bit of the 3 bits, discarding the 2 LSBs, thus the interface would be similar to a 16.384Mhz synchronous (clocked) serial interface.
Should I be looking for another solution, or am I missing something?
(edit: I realize that the chip needs HSE at 32Mhz for BT, NFC etc. I'll solve this problem later)