Datasheet

Breakpoint (BKP) Module
MC9S12DP256 — Revision 1.1
Breakpoint (BKP) Module
The x:0 case is for a Full Address Compare. When a program page is
selected the full address compare will be based on bits
{mmc_xab[19:14],mmc_ab_t2[13:0]} for a 20-bit compare. The
registers used for the compare are
{BKP0X[5:0],BKP0H[5:0],BKP0L[7:0]}. When a program page is not
selected the full address compare will be based on bits
mmc_ab_t2[15:0] for a 16-bit compare. The registers used for the
compare are {BKP0H[7:0],BKP0L[7:0]}.
The 1:0 case is not sensible because it would ignore the high order
address and compare the low order and expansion addresses. Logic
forces this case to compare all address lines (effectively ignoring the
BK0MBH control bit).
The 1:1 case is useful for triggering a breakpoint on any access to a
particular expansion page. This only makes sense if a program page
is being accessed so the breakpoint trigger will only occur if BKP0X
compares.
Table 124 Breakpoint Mask Bits for First Address
BK0MBH:BK0MBL Address Compare BKP0X BKP0H BKP0L
x:0 Full Address Compare
Ye s
(1)
Ye s Ye s
0:1 256 byte Address Range
Ye s
(1)
Ye s N o
1:1 16K byte Address Range
Ye s
(1)
No No
1. If page is selected.
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