There have been several questions on the forum over the years about using the Udoo Bolt's SPI directly from Linux, but with few definitive answers. Some users simply point to trying an Arduino solution to get to SPI or using the EAPI, but no one has followed up on which of these may have worked for them. More specifically, no one has definitively answered whether or not SPI, like UART, can be directly seen in modern Linux kernels. Unfortunately, there is a Carriage Return typo on the main Udoo page where it wasn't obvious when I purchased the Bolt that the SPI is part of an Embedded Controller, and not natively supported on the board. However, I do like the platform despite this, and I am hopeful that perhaps someone out there got this working under Linux without the need for the EAPI. If so, I'd greatly appreciate any help you might provide. Why no EAPI? I was hoping to use the Udoo Bolt to connect, via SPI, to a carrier board with the MCP2517FD chipset. The MCP chipset has native SPI driver support in the Linux 5.11 kernel, and therefore it is not really practical for me to use the EAPI library, as I want to talk directly to that chip via SPI.