Hi Gef
Those expansion devices over I2C will not be much good at all for analog signals. They are really suitable for low speed digital IO. There are SPI versions of these devices available that can obviously increase the update bandwidth...
This seems very curious and not the norm:
Typically the SPI bus is shared and additional CS lines are used to select the chip you want to talk to. Why are they doing it this way?
bigDlin do you have them wired this way? Is it working?
Also I...
Is the data actually 32bits? or is it a 24bit converter sending a 4byte result?
Depending on the converter, some will allow the result (eg ADC) to be sent as 3 bytes (24bits) instead of the 32 saying you 25% throughput.
I had been using PCBWay for everything up until recently when they dramatically increased their pricing on 4 layer boards.
A 100mm x 100mm 4 layer board from PCB Way is about 4 to 5 times the price of the same design from JLCPCB which I found...
SdFat is blocking for both read and write. There is a fairly recent thread where someone modified SdFat to do non-blocking reads, but not writes. There is a way, though, to limit blocking times to 5-6 us and avoid the very long blocking times of...