My project writes to 0x70 (and other registers) and generates an ip2bus_wrack, but no spi_xferack. This results in an opb_timeout. When I switch to v1.00.b, it fixes the issue.
The latest version of OPB SPI Core (opb_spi v1.00.c) uses a helper library "opb_ipif_v3_01_a" core.
In this release, the helper library has been modified, causing the OPB SPI Core and other OPB Slave Cores that use this helper library (opb_ipif_v3_01_a) to fail in the system (including any timing issues).
This issue was fixed by eliminating the reset of the posted write inhibit signal when OPB_Select negates.
A patch is available for download that will fix this problem at:
Download the patch to the "pcore" sub-directory (in your project directory) and compile the design.
NOTE: This patch has the same version as the existing library in the EDK build.