9.7 Coherency Support
When a PFM programming event occurs flash programming initiated by the Flash controller, the Prefetch module invalidates all lines and the contents of the prefetch buffer. If a transaction is in progress, the invalidation occurs after completion. When programming or erasing a Flash page, a read of that Flash page will cause the transaction to stall until the erase or program event completes.
- Auto Invalidate via I/D/A CHECOH
- Manual Invalidate via I/D/A CHEINV
The user can choose to auto invalidate the each/any cache on a PFM programming event by setting *CHECOH = 1. This is the safest option. However, the user has the option to never auto invalidate each/any cache by setting *CHECOH = 0.
In addition to using *CHECOH, *CHEINV can be used as an alternate invalidate method to invalidate each/any cache manually. If using *CHEINV to manually invalidate each/any cache due to a PFM programming event, stop all instruction/data fetches from the desired Flash, set *CHEINV, wait for it to clear and, then, start the programming sequence. When using *CHEINV to invalidate each/any cache for reasons other than programming, it can be set at any time but only takes effect after any pending transactions complete.