Releases: haxar/OpenXenium
qpi-v20220704
OpenXenium QPI is a design variant & fork of Ryzee119's genuine Xenium replacement project, an LPC flash peripheral (aka. "modchip") for the original Xbox, by haxar. This design uses modern Winbond SPI flash, rather than parallel flash, in a Winbond compatible QPI mode utilized as a 1:1 bridge to the LPC bus for LPC memory transactions, via the current VHDL firmware implementation. This is made possible by swapping out the limiting (100% utilized 72 macrocell) Xilinx CPLD used by the original Xenium design for a more capable Xilinx Spartan-3A FPGA.
The SPI flash chip placed at U2 will need to be programmed with the FPGA bitstream first before placing on the board, at the bottom/beginning of flash with the given release .bit file (or .bit.img.xz file uncompressed for flashrom). Importantly, R4, R6 & R7 10k ohm pull-up resistors need to be placed first before its respective SPI flash chip for soldering convenience.
Writing software for this new QPI design is currently a work in progress to make use of the extra non-volatile storage. While the SPI flash chip used is 16 megabytes in size compared to the usual 2 megabytes of the former parallel flash design, as well as having 2 extra software selectable SPI flash chips on the board, not all of the extra storage can be utilized by the current XeniumOS. XeniumOS v2.3.1 (without MakeMHz patches) & Xenium-Tools are compatible with this design, even if only one SPI flash chip is placed (at U2) on the board.
This release currently does not contain VHDL firmware code for the optional exposed UART (with SMI active-low receive interrupt) & SMBus pins.