9.2.2. Using the mask registers

For each Value register in a register pair, there is a Mask register of the same format. Setting a bit to 1 in the Mask register has the effect of disregarding the corresponding bit in the Value register in the comparison. For example, if a watchpoint is required on a particular memory location but the data value is irrelevant, the Data Mask register can be programmed to 0xFFFFFFFF (all bits set to 1) to make the entire Data Bus field ignored.

Note

The mask is an XNOR mask rather than a conventional AND mask. When a mask bit is set to 1, the comparator for that bit position always matches, irrespective of the value register or the input value.

Setting the mask bit to 0 means that the comparator only matches if the input value matches the value programmed into the value register.

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