Datasheet

489
SAM9N12/SAM9CN11/SAM9CN12 [DATASHEET]
11063K–ATARM–05-Nov-13
32.7 Write Protection Registers
To prevent any single software error that may corrupt the DMAC behavior, the DMAC address space can be write
protected by setting the WPEN bit in the “DMAC Write Protect Mode Register” (DMAC_WPMR).
If a write access to anywhere in the DMAC address space is detected, then the WPVS flag in the DMAC Write Protect
Status Register (MCI_WPSR) is set, and the WPVSRC field indicates in which register the write access has been
attempted.
The WPVS flag is reset by writing the DMAC Write Protect Mode Register (DMAC_WPMR) with the appropriate access
key, WPKEY.
The write protected registers are:
 “DMAC Global Configuration Register” on page 491
 “DMAC Enable Register” on page 492
 “DMAC Channel x [x = 0..7] Source Address Register” on page 503
 “DMAC Channel x [x = 0..7] Destination Address Register” on page 504
 “DMAC Channel x [x = 0..7] Descriptor Address Register” on page 505
 “DMAC Channel x [x = 0..7] Control A Register” on page 506
 “DMAC Channel x [x = 0..7] Control B Register” on page 508
 “DMAC Channel x [x = 0..7] Configuration Register” on page 510