Windows sd card setup for dual partitions

Question

I need to setup a micro SD card in a particular way, but I'm unsure how to do it from Windows (unable to use any Linux machine in my current setup).

There needs to be 2 partitions: One is a standard fat32 file system, and the other is a raw partition with a specific partition ID in which a raw binary file will get written.

I've only used diskpart and win32disk imager on single partition setups, so I'm not entirely sure how to do this. I've messed around a bit with trying to get dual partitions in diskpart, but I never get to the point of being able to mount to the fat32 fs and load files.

Can someone walk me through the steps?

Answer 1

As far as I know, Windows releases prior 10 are not handling multiple partitions on USB devices (as an SD card get's connected to the system this way). But you can use any partitioning tool (for Windows), they are all capable to do this. Take for ex. "Minitool Partition Wizard Free" from here https://www.partitionwizard.com/free-partition-manager.html Do this, step by step, all in one batch, in MTPW: (If needed, delete all existing partitions.)

1. Create your first fat32 partition (with the sizing considering both). Let it be formatted by defaults during this step.
2. Make it "hidden".
3. Create the other one in the free space left over, as fat32 (or else that your system is able to handle). Let it be formatted by defaults during this step.
4. Assign a drive letter (windows might do it as well, but you can do it from MTPW)
5. As you have now the drive letter assigned, write your binary on it with any external tool or explorer itself.
6. In MTPW again, in a next batch, remove the drive letter for the 2nd partition.
7. Change the partition ID as required for your use: if needed, use the option "enter manually". (might I ask what this ID is?)
8. Unhide the first (fat32) partition.

If you don't want windows to write anything on it, and if a drive letter is assigned automatically when "unhidden", just remove the drive letter immediately. And you are done. (Of course, don't do this step, if you need to access it from your OS...)