11.5.7 Tightly Coupled Memory

Users can use a part of the cache as Tightly Coupled Memory (TCM). The cache size is determined by the Cache Size Configuration by Software bits in the Cache Configuration register (CFG.CSIZESW). The relation between cache and TCM is as given below:

TCM size = maximum Cache size - configured Cache size.

The TCM start address can be obtained from the product memory mapping. The cache memory starts first from the address followed by the TCM memory. Size of the Way is fixed and the number of ways varies according to the available size for the cache memory. For additional information, refer to the section Product Memory Mapping.

Table 11-1. TCM Sizes
Max. Cache Configured Cache TCM Size
4 KB 4 KB 0 KB
4 KB 1 KB 3 KB
4 KB 2 KB 2 KB
4 KB 0 KB 4 KB

The TCM is also accessible in its maximum size when the CMCC is disabled. The TCM does not need to be locked in order to operate.

Note: Writing into the cache DATA RAM region through the CPU can overwrite the valid cache lines. This can result in data corruption when the cache controller is accessing the data for cache transactions. Access the DATA RAM region only after configuring it as TCM.