diff --git a/reference/FPGA-TN-1251-iCE40sysCLOCKPLLDesignandUsageGuide.pdf b/reference/FPGA-TN-1251-iCE40sysCLOCKPLLDesignandUsageGuide.pdf new file mode 100644 index 0000000..bd3aa8c Binary files /dev/null and b/reference/FPGA-TN-1251-iCE40sysCLOCKPLLDesignandUsageGuide.pdf differ diff --git a/reference/XTAL-ECS-2520MV.pdf b/reference/XTAL-ECS-2520MV.pdf new file mode 100644 index 0000000..591f276 Binary files /dev/null and b/reference/XTAL-ECS-2520MV.pdf differ