Datasheet

503
SAM9X25 [DATASHEET]
11054E–ATARM–10-Mar-2014
31.6 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 protected registers are:
 “DMAC Global Configuration Register” on page 505
 “DMAC Enable Register” on page 506
 “DMAC Channel x [x = 0..7] Source Address Register” on page 517
 “DMAC Channel x [x = 0..7] Destination Address Register” on page 518
 “DMAC Channel x [x = 0..7] Descriptor Address Register” on page 519
 “DMAC Channel x [x = 0..7] Control A Register” on page 520
 “DMAC Channel x [x = 0..7] Control B Register” on page 522
 “DMAC Channel x [x = 0..7] Configuration Register” on page 524
 “DMAC Channel x [x = 0..7] Source Picture-in-Picture Configuration Register” on page 526
 “DMAC Channel x [x = 0..7] Destination Picture-in-Picture Configuration Register” on page 527