Hey guys, I am working on an academic cubesat project and have been running into issues with our imaging board and cant seem to pinpoint the issue. I wasn't the original person who designed the board so I am trying to put everything together as I go along, but the primary concern here is getting the Arduino Pro Mini (3.3V) to initialize the SD card reader (using a 3M 2908-08-05WB-MG). Between the Pro Mini and the SD reader is a CD74HC4050 level shifter and also a LP2985 voltage regulator.
Here is the schematic for the connections, it seems like a near copy of the adafruit design found here.
Originally, the way the board is designed, there was no power being fed into the voltage regulator's on/off/sleep switch, so Vout was reading 0 and not 3.3V, and the SD card reader was not being powered. I have since fixed that by attaching a wire to VCC and the SD card is now getting 3.3V.
I am still not able to initialize the SD card and I have read through quite a lot of forums about it, but it seems like most peoples issues stem from them having incorrect connections or having the wrong chip select pin in their code. I think the next most likely candidate would be an issue with the card detect?
I have probed the level shifter and it reads 3.3V on the trace that connects pin 2/CS on the SD card regardless if the card is inserted or not.
The current code, which I have been running on a separate Mega 2560, checks out and works fine (obviously different pins). But for whatever reason the Pro Mini wont even recognize the SD card whatsoever. I'm using a SanDisk ultra 16gb, and have checked a few times to make sure its functional and formatted correctly, but there just doesnt seem to be any feedback from the SD reader to the Mini - for instance SD.begin doesn't return anything.
I have tried a combination of SPI speeds/pinMode(CS, OUTPUT)/digitalWrite/etc and still nothing.
Apologies for the hard to read photo, new users cant post more than one image/multiple links. Any help on this would be much appreciated.