Yifan Lu one of the main players of the PSVita Hacking scene recently posted about a custom built Micro sd adapter for the Playstation Vita, I myself brought one of these but it wouldn't fit in the slot and the only place where it would fit was the game slot and crashed my console so in the bucket of rubbish it has gone, heres a snippet from his news:

One thing I love about Vita hacking is the depth of it. After investing so much time reverse engineering the software and hardware, you think you would run out of things to hack. Each loose end leads to another month long project. This all started in the development of HENkaku Ensō. We wanted an easy way to print debug statements early in boot. UART was a good candidate because the device initialization is very simple and the protocol is standard. The Vita SoC (likely called Kermit internally as we’ll see later on) has seven UART ports. However, it is unlikely they are all hooked up on a retail console. After digging through the kernel code, I found that bbmc.skprx, the 3G modem driver contain references to UART. After a trusty FCC search, it turns out that the Vita’s 3G modem uses a mini-PCIe connector but with a custom pin layout and a custom form factor. The datasheet gives some useful description for each pin, and UART_KERMIT seemed like the most likely candidate (there’s also UART_SYSCON which is connected to the SCEI chip on the bottom of the board, which serves as a system controller and a UART_EXT which is not hooked up on the Vita side). So finding a debug output port was a success, but with the datasheet in front of me, the USB port caught my attention. Wouldn’t it be neat to put in a custom USB device?

Full details Here --> http://yifan.lu/2017/08/22/psvsd-cus...-card-adapter/