AR# 53438: Soft Error Mitigation (SEM) v3.4 - Updated EXT shim module for use with 512 Mb and 1 Gb SPI Flash
Soft Error Mitigation (SEM) v3.4 - Updated EXT shim module for use with 512 Mb and 1 Gb SPI Flash
When the SEM v3.4 IP is configured with the Correction by Replace or Classification features enabled, an external memory is required to store the data for these feature sets. The example design generated with the IP contains a shim that interfaces to an external SPI Flash, <component_name>_sem_ext.v[hd]. This generated EXT shim is designed for legacy SPI Flash devices supporting the fast read command (0x0B), with one byte of dummy cycles prior to data validity. The EXT shim issues the enable four-byte addressing command (0xB7) when the density of the required SPI Flash exceeds 128 Mb.
If the external storage device is a 512 Mb Flash or a 1 Gb SPI Flash, additional SPI Flash configuration commands are required (e.g. write enable command, write volatile config register). For these cases, replace this example file with the EXT shim file provided in this answer record (sem_ext.zip). This example EXT shim applies to designs targeting Virtex-7 SSI devices (XC7VH580T, XC7VH870T, XC7VX1140T, XC7VX2000T), and must be modified if needed to support other devices.
The SEM solution has been tested with this replacement EXT shim on the following SPI Flash devices: