Atmel SAM9X25, Manual

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31.6 Write Protection Registers
To prevent any single software error that may corrupt DMAC behavior, the DMAC address
space can be write-protected by setting the WPEN bit in the
“DMAC Write Protect Mode Regis-
ter” (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 field WPVSRC 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 503
• “DMAC Enable Register” on page 504
• “DMAC Channel x [x = 0..7] Source Address Register” on page 514
• “DMAC Channel x [x = 0..7] Destination Address Register” on page 515
• “DMAC Channel x [x = 0..7] Descriptor Address Register” on page 516
• “DMAC Channel x [x = 0..7] Control A Register” on page 517
• “DMAC Channel x [x = 0..7] Control B Register” on page 519
• “DMAC Channel x [x = 0..7] Configuration Register” on page 521
• “DMAC Channel x [x = 0..7] Source Picture in Picture Configuration Register” on page 523
• “DMAC Channel x [x = 0..7] Destination Picture in Picture Configuration Register” on page
524