CPU_DWT

Instance: CPU_DWT
Component: CPU_DWT
Base address: 0xE0001000


Cortex-M's Data watchpoint and Trace (DWT)

TOP:CPU_DWT Register Summary

Register Name

Type

Register Width (Bits)

Register Reset

Address Offset

Physical Address

CTRL

RW

32

0x4000 0000

0x0000 0000

0xE000 1000

CYCCNT

RW

32

0x0000 0000

0x0000 0004

0xE000 1004

CPICNT

RW

32

0x0000 00XX

0x0000 0008

0xE000 1008

EXCCNT

RW

32

0x0000 00XX

0x0000 000C

0xE000 100C

SLEEPCNT

RW

32

0x0000 00XX

0x0000 0010

0xE000 1010

LSUCNT

RW

32

0x0000 00XX

0x0000 0014

0xE000 1014

FOLDCNT

RW

32

0x0000 00XX

0x0000 0018

0xE000 1018

PCSR

RO

32

0xXXXX XXXX

0x0000 001C

0xE000 101C

COMP0

RW

32

0xXXXX XXXX

0x0000 0020

0xE000 1020

MASK0

RW

32

0x0000 000X

0x0000 0024

0xE000 1024

FUNCTION0

RW

32

0x0000 0000

0x0000 0028

0xE000 1028

COMP1

RW

32

0xXXXX XXXX

0x0000 0030

0xE000 1030

MASK1

RW

32

0x0000 000X

0x0000 0034

0xE000 1034

FUNCTION1

RW

32

0x0000 0200

0x0000 0038

0xE000 1038

COMP2

RW

32

0xXXXX XXXX

0x0000 0040

0xE000 1040

MASK2

RW

32

0x0000 000X

0x0000 0044

0xE000 1044

FUNCTION2

RW

32

0x0000 0000

0x0000 0048

0xE000 1048

COMP3

RW

32

0xXXXX XXXX

0x0000 0050

0xE000 1050

MASK3

RW

32

0x0000 000X

0x0000 0054

0xE000 1054

FUNCTION3

RW

32

0x0000 0000

0x0000 0058

0xE000 1058

TOP:CPU_DWT Register Descriptions

TOP:CPU_DWT:CTRL

Address Offset 0x0000 0000
Physical Address 0xE000 1000 Instance 0xE000 1000
Description Control
Use the DWT Control Register to enable the DWT unit.
Type RW
Bits Field Name Description Type Reset
31:26 RESERVED26 Software should not rely on the value of a reserved. Writing any other value than the reset value may result in undefined behavior. RW 0b01 0000
25 NOCYCCNT When set, CYCCNT is not supported. RW 0
24 NOPRFCNT When set, FOLDCNT, LSUCNT, SLEEPCNT, EXCCNT, and CPICNT are not supported. RW 0
23 RESERVED23 Software should not rely on the value of a reserved. Writing any other value than the reset value may result in undefined behavior. RW 0
22 CYCEVTENA Enables Cycle count event. Emits an event when the POSTCNT counter triggers it. See CYCTAP and POSTPRESET for details. This event is only emitted if PCSAMPLEENA is disabled. PCSAMPLEENA overrides the setting of this bit.

0: Cycle count events disabled
1: Cycle count events enabled
RW 0
21 FOLDEVTENA Enables Folded instruction count event. Emits an event when FOLDCNT overflows (every 256 cycles of folded instructions). A folded instruction is one that does not incur even one cycle to execute. For example, an IT instruction is folded away and so does not use up one cycle.

0: Folded instruction count events disabled.
1: Folded instruction count events enabled.
RW 0
20 LSUEVTENA Enables LSU count event. Emits an event when LSUCNT overflows (every 256 cycles of LSU operation). LSU counts include all LSU costs after the initial cycle for the instruction.

0: LSU count events disabled.
1: LSU count events enabled.
RW 0
19 SLEEPEVTENA Enables Sleep count event. Emits an event when SLEEPCNT overflows (every 256 cycles that the processor is sleeping).

0: Sleep count events disabled.
1: Sleep count events enabled.
RW 0
18 EXCEVTENA Enables Interrupt overhead event. Emits an event when EXCCNT overflows (every 256 cycles of interrupt overhead).

0x0: Interrupt overhead event disabled.
0x1: Interrupt overhead event enabled.
RW 0
17 CPIEVTENA Enables CPI count event. Emits an event when CPICNT overflows (every 256 cycles of multi-cycle instructions).

0: CPI counter events disabled.
1: CPI counter events enabled.
RW 0
16 EXCTRCENA Enables Interrupt event tracing.

0: Interrupt event trace disabled.
1: Interrupt event trace enabled.
RW 0
15:13 RESERVED13 Software should not rely on the value of a reserved. Writing any other value than the reset value may result in undefined behavior. RW 0b000
12 PCSAMPLEENA Enables PC Sampling event. A PC sample event is emitted when the POSTCNT counter triggers it. See CYCTAP and POSTPRESET for details. Enabling this bit overrides CYCEVTENA.

0: PC Sampling event disabled.
1: Sampling event enabled.
RW 0
11:10 SYNCTAP Selects a synchronization packet rate. CYCCNTENA and CPU_ITM:TCR.SYNCENA must also be enabled for this feature.
Synchronization packets (if enabled) are generated on tap transitions (0 to1 or 1 to 0).
Value ENUM Name Description
0x0 DIS Disabled. No synchronization packets
0x1 BIT24 Tap at bit 24 of CYCCNT
0x2 BIT26 Tap at bit 26 of CYCCNT
0x3 BIT28 Tap at bit 28 of CYCCNT
RW 0b00
9 CYCTAP Selects a tap on CYCCNT. These are spaced at bits [6] and [10]. When the selected bit in CYCCNT changes from 0 to 1 or 1 to 0, it emits into the POSTCNT, post-scalar counter. That counter then counts down. On a bit change when post-scalar is 0, it triggers an event for PC sampling or cycle count event (see details in CYCEVTENA).
Value ENUM Name Description
0x0 BIT6 Selects bit [6] to tap
0x1 BIT10 Selects bit [10] to tap
RW 0
8:5 POSTCNT Post-scalar counter for CYCTAP. When the selected tapped bit changes from 0 to 1 or 1 to 0, the post scalar counter is down-counted when not 0. If 0, it triggers an event for PCSAMPLEENA or CYCEVTENA use. It also reloads with the value from POSTPRESET. RW 0x0
4:1 POSTPRESET Reload value for post-scalar counter POSTCNT. When 0, events are triggered on each tap change (a power of 2). If this field has a non-0 value, it forms a count-down value, to be reloaded into POSTCNT each time it reaches 0. For example, a value 1 in this register means an event is formed every other tap change. RW 0x0
0 CYCCNTENA Enable CYCCNT, allowing it to increment and generate synchronization and count events. If NOCYCCNT = 1, this bit reads zero and ignore writes. RW 0

TOP:CPU_DWT:CYCCNT

Address Offset 0x0000 0004
Physical Address 0xE000 1004 Instance 0xE000 1004
Description Current PC Sampler Cycle Count
This register is used to count the number of core cycles. This counter can measure elapsed execution time. This is a free-running counter (this counter will not advance in power modes where free-running clock to CPU stops). The counter has three functions:

1: When CTRL.PCSAMPLEENA = 1, the PC is sampled and emitted when the selected tapped bit changes value (0 to 1 or 1 to 0) and any post-scalar value counts to 0.
2: When CTRL.CYCEVTENA = 1 , (and CTRL.PCSAMPLEENA = 0), an event is emitted when the selected tapped bit changes value (0 to 1 or 1 to 0) and any post-scalar value counts to 0.
3: Applications and debuggers can use the counter to measure elapsed execution time. By subtracting a start and an end time, an application can measure time between in-core clocks (other than when Halted in debug). This is valid to 2^32 core clock cycles (for example, almost 89.5 seconds at 48MHz).
Type RW
Bits Field Name Description Type Reset
31:0 CYCCNT Current PC Sampler Cycle Counter count value. When enabled, this counter counts the number of core cycles, except when the core is halted. The cycle counter is a free running counter, counting upwards (this counter will not advance in power modes where free-running clock to CPU stops). It wraps around to 0 on overflow. The debugger must initialize this to 0 when first enabling. RW 0x0000 0000

TOP:CPU_DWT:CPICNT

Address Offset 0x0000 0008
Physical Address 0xE000 1008 Instance 0xE000 1008
Description CPI Count
This register is used to count the total number of instruction cycles beyond the first cycle.
Type RW
Bits Field Name Description Type Reset
31:8 RESERVED8 Software should not rely on the value of a reserved. Writing any other value than the reset value may result in undefined behavior. RW 0x00 0000
7:0 CPICNT Current CPI counter value. Increments on the additional cycles (the first cycle is not counted) required to execute all instructions except those recorded by LSUCNT. This counter also increments on all instruction fetch stalls. If CTRL.CPIEVTENA is set, an event is emitted when the counter overflows. This counter initializes to 0 when it is enabled using CTRL.CPIEVTENA. RW 0xXX

TOP:CPU_DWT:EXCCNT

Address Offset 0x0000 000C
Physical Address 0xE000 100C Instance 0xE000 100C
Description Exception Overhead Count
This register is used to count the total cycles spent in interrupt processing.
Type RW
Bits Field Name Description Type Reset
31:8 RESERVED8 Software should not rely on the value of a reserved. Writing any other value than the reset value may result in undefined behavior. RW 0x00 0000
7:0 EXCCNT Current interrupt overhead counter value. Counts the total cycles spent in interrupt processing (for example entry stacking, return unstacking, pre-emption). An event is emitted on counter overflow (every 256 cycles). This counter initializes to 0 when it is enabled using CTRL.EXCEVTENA. RW 0xXX

TOP:CPU_DWT:SLEEPCNT

Address Offset 0x0000 0010
Physical Address 0xE000 1010 Instance 0xE000 1010
Description Sleep Count
This register is used to count the total number of cycles during which the processor is sleeping.
Type RW
Bits Field Name Description Type Reset
31:8 RESERVED8 Software should not rely on the value of a reserved. Writing any other value than the reset value may result in undefined behavior. RW 0x00 0000
7:0 SLEEPCNT Sleep counter. Counts the number of cycles during which the processor is sleeping. An event is emitted on counter overflow (every 256 cycles). This counter initializes to 0 when it is enabled using CTRL.SLEEPEVTENA. Note that the sleep counter is clocked using CPU's free-running clock. In some power modes the free-running clock to CPU is gated to minimize power consumption. This means that the sleep counter will be invalid in these power modes. RW 0xXX

TOP:CPU_DWT:LSUCNT

Address Offset 0x0000 0014
Physical Address 0xE000 1014 Instance 0xE000 1014
Description LSU Count
This register is used to count the total number of cycles during which the processor is processing an LSU operation beyond the first cycle.
Type RW
Bits Field Name Description Type Reset
31:8 RESERVED8 Software should not rely on the value of a reserved. Writing any other value than the reset value may result in undefined behavior. RW 0x00 0000
7:0 LSUCNT LSU counter. This counts the total number of cycles that the processor is processing an LSU operation. The initial execution cost of the instruction is not counted. For example, an LDR that takes two cycles to complete increments this counter one cycle. Equivalently, an LDR that stalls for two cycles (i.e. takes four cycles to execute), increments this counter three times. An event is emitted on counter overflow (every 256 cycles). This counter initializes to 0 when it is enabled using CTRL.LSUEVTENA. RW 0xXX

TOP:CPU_DWT:FOLDCNT

Address Offset 0x0000 0018
Physical Address 0xE000 1018 Instance 0xE000 1018
Description Fold Count
This register is used to count the total number of folded instructions. The counter increments on each instruction which takes 0 cycles.
Type RW
Bits Field Name Description Type Reset
31:8 RESERVED8 Software should not rely on the value of a reserved. Writing any other value than the reset value may result in undefined behavior. RW 0x00 0000
7:0 FOLDCNT This counts the total number folded instructions. This counter initializes to 0 when it is enabled using CTRL.FOLDEVTENA. RW 0xXX

TOP:CPU_DWT:PCSR

Address Offset 0x0000 001C
Physical Address 0xE000 101C Instance 0xE000 101C
Description Program Counter Sample
This register is used to enable coarse-grained software profiling using a debug agent, without changing the currently executing code. If the core is not in debug state, the value returned is the instruction address of a recently executed instruction. If the core is in debug state, the value returned is 0xFFFFFFFF.
Type RO
Bits Field Name Description Type Reset
31:0 EIASAMPLE Execution instruction address sample, or 0xFFFFFFFF if the core is halted. RO 0xXXXX XXXX

TOP:CPU_DWT:COMP0

Address Offset 0x0000 0020
Physical Address 0xE000 1020 Instance 0xE000 1020
Description Comparator 0
This register is used to write the reference value for comparator 0.
Type RW
Bits Field Name Description Type Reset
31:0 COMP Reference value to compare against PC or the data address as given by FUNCTION0. Comparator 0 can also compare against the value of the PC Sampler Counter (CYCCNT). RW 0xXXXX XXXX

TOP:CPU_DWT:MASK0

Address Offset 0x0000 0024
Physical Address 0xE000 1024 Instance 0xE000 1024
Description Mask 0
Use the DWT Mask Registers 0 to apply a mask to data addresses when matching against COMP0.
Type RW
Bits Field Name Description Type Reset
31:4 RESERVED4 Software should not rely on the value of a reserved. Writing any other value than the reset value may result in undefined behavior. RW 0x000 0000
3:0 MASK Mask on data address when matching against COMP0. This is the size of the ignore mask. That is, DWT matching is performed as:(ADDR ANDed with (0xFFFF left bit-shifted by MASK)) == COMP0. However, the actual comparison is slightly more complex to enable matching an address wherever it appears on a bus. So, if COMP0 is 3, this matches a word access of 0, because 3 would be within the word. RW 0xX

TOP:CPU_DWT:FUNCTION0

Address Offset 0x0000 0028
Physical Address 0xE000 1028 Instance 0xE000 1028
Description Function 0
Use the DWT Function Registers 0 to control the operation of the comparator 0. This comparator can:
1. Match against either the PC or the data address. This is controlled by CYCMATCH. This function is only available for comparator 0 (COMP0).
2. Emit data or PC couples, trigger the ETM, or generate a watchpoint depending on the operation defined by FUNCTION.
Type RW
Bits Field Name Description Type Reset
31:25 RESERVED25 Software should not rely on the value of a reserved. Writing any other value than the reset value may result in undefined behavior. RO 0b000 0000
24 MATCHED This bit is set when the comparator matches, and indicates that the operation defined by FUNCTION has occurred since this bit was last read. This bit is cleared on read. RW 0
23:8 RESERVED8 Software should not rely on the value of a reserved. Writing any other value than the reset value may result in undefined behavior. RO 0x0000
7 CYCMATCH This bit is only available in comparator 0. When set, COMP0 will compare against the cycle counter (CYCCNT). RW 0
6 RESERVED6 Software should not rely on the value of a reserved. Writing any other value than the reset value may result in undefined behavior. RO 0
5 EMITRANGE Emit range field. This bit permits emitting offset when range match occurs. PC sampling is not supported when emit range is enabled.
This field only applies for: FUNCTION = 1, 2, 3, 12, 13, 14, and 15.
RW 0
4 RESERVED4 Software should not rely on the value of a reserved. Writing any other value than the reset value may result in undefined behavior. RO 0
3:0 FUNCTION Function settings.

0x0: Disabled
0x1: EMITRANGE = 0, sample and emit PC through ITM. EMITRANGE = 1, emit address offset through ITM
0x2: EMITRANGE = 0, emit data through ITM on read and write. EMITRANGE = 1, emit data and address offset through ITM on read or write.
0x3: EMITRANGE = 0, sample PC and data value through ITM on read or write. EMITRANGE = 1, emit address offset and data value through ITM on read or write.
0x4: Watchpoint on PC match.
0x5: Watchpoint on read.
0x6: Watchpoint on write.
0x7: Watchpoint on read or write.
0x8: ETM trigger on PC match
0x9: ETM trigger on read
0xA: ETM trigger on write
0xB: ETM trigger on read or write
0xC: EMITRANGE = 0, sample data for read transfers. EMITRANGE = 1, sample Daddr (lower 16 bits) for read transfers
0xD: EMITRANGE = 0, sample data for write transfers. EMITRANGE = 1, sample Daddr (lower 16 bits) for write transfers
0xE: EMITRANGE = 0, sample PC + data for read transfers. EMITRANGE = 1, sample Daddr (lower 16 bits) + data for read transfers
0xF: EMITRANGE = 0, sample PC + data for write transfers. EMITRANGE = 1, sample Daddr (lower 16 bits) + data for write transfers

Note 1: If the ETM is not fitted, then ETM trigger is not possible.
Note 2: Data value is only sampled for accesses that do not fault (MPU or bus fault). The PC is sampled irrespective of any faults. The PC is only sampled for the first address of a burst.
Note 3: PC match is not recommended for watchpoints because it stops after the instruction. It mainly guards and triggers the ETM.
RW 0x0

TOP:CPU_DWT:COMP1

Address Offset 0x0000 0030
Physical Address 0xE000 1030 Instance 0xE000 1030
Description Comparator 1
This register is used to write the reference value for comparator 1.
Type RW
Bits Field Name Description Type Reset
31:0 COMP Reference value to compare against PC or the data address as given by FUNCTION1.
Comparator 1 can also compare data values. So this register can contain reference values for data matching.
RW 0xXXXX XXXX

TOP:CPU_DWT:MASK1

Address Offset 0x0000 0034
Physical Address 0xE000 1034 Instance 0xE000 1034
Description Mask 1
Use the DWT Mask Registers 1 to apply a mask to data addresses when matching against COMP1.
Type RW
Bits Field Name Description Type Reset
31:4 RESERVED4 Software should not rely on the value of a reserved. Writing any other value than the reset value may result in undefined behavior. RW 0x000 0000
3:0 MASK Mask on data address when matching against COMP1. This is the size of the ignore mask. That is, DWT matching is performed as:(ADDR ANDed with (0xFFFF left bit-shifted by MASK)) == COMP1. However, the actual comparison is slightly more complex to enable matching an address wherever it appears on a bus. So, if COMP1 is 3, this matches a word access of 0, because 3 would be within the word. RW 0xX

TOP:CPU_DWT:FUNCTION1

Address Offset 0x0000 0038
Physical Address 0xE000 1038 Instance 0xE000 1038
Description Function 1
Use the DWT Function Registers 1 to control the operation of the comparator 1. This comparator can:
1. Perform data value comparisons if associated address comparators have performed an address match. This function is only available for comparator 1 (COMP1).
2. Emit data or PC couples, trigger the ETM, or generate a watchpoint depending on the operation defined by FUNCTION.
Type RW
Bits Field Name Description Type Reset
31:25 RESERVED25 Software should not rely on the value of a reserved. Writing any other value than the reset value may result in undefined behavior. RO 0b000 0000
24 MATCHED This bit is set when the comparator matches, and indicates that the operation defined by FUNCTION has occurred since this bit was last read. This bit is cleared on read. RW 0
23:20 RESERVED20 Software should not rely on the value of a reserved. Writing any other value than the reset value may result in undefined behavior. RO 0x0
19:16 DATAVADDR1 Identity of a second linked address comparator for data value matching when DATAVMATCH == 1 and LNK1ENA == 1. RW 0x0
15:12 DATAVADDR0 Identity of a linked address comparator for data value matching when DATAVMATCH == 1. RW 0x0
11:10 DATAVSIZE Defines the size of the data in the COMP1 register that is to be matched:

0x0: Byte
0x1: Halfword
0x2: Word
0x3: Unpredictable.
RW 0b00
9 LNK1ENA Read only bit-field only supported in comparator 1.

0: DATAVADDR1 not supported
1: DATAVADDR1 supported (enabled)
RO 1
8 DATAVMATCH Data match feature:

0: Perform address comparison
1: Perform data value compare. The comparators given by DATAVADDR0 and DATAVADDR1 provide the address for the data comparison. The FUNCTION setting for the comparators given by DATAVADDR0 and DATAVADDR1 are overridden and those comparators only provide the address match for the data comparison.

This bit is only available in comparator 1.
RW 0
7:6 RESERVED6 Software should not rely on the value of a reserved. Writing any other value than the reset value may result in undefined behavior. RO 0b00
5 EMITRANGE Emit range field. This bit permits emitting offset when range match occurs. PC sampling is not supported when emit range is enabled.
This field only applies for: FUNCTION = 1, 2, 3, 12, 13, 14, and 15.
RW 0
4 RESERVED4 Software should not rely on the value of a reserved. Writing any other value than the reset value may result in undefined behavior. RO 0
3:0 FUNCTION Function settings:

0x0: Disabled
0x1: EMITRANGE = 0, sample and emit PC through ITM. EMITRANGE = 1, emit address offset through ITM
0x2: EMITRANGE = 0, emit data through ITM on read and write. EMITRANGE = 1, emit data and address offset through ITM on read or write.
0x3: EMITRANGE = 0, sample PC and data value through ITM on read or write. EMITRANGE = 1, emit address offset and data value through ITM on read or write.
0x4: Watchpoint on PC match.
0x5: Watchpoint on read.
0x6: Watchpoint on write.
0x7: Watchpoint on read or write.
0x8: ETM trigger on PC match
0x9: ETM trigger on read
0xA: ETM trigger on write
0xB: ETM trigger on read or write
0xC: EMITRANGE = 0, sample data for read transfers. EMITRANGE = 1, sample Daddr (lower 16 bits) for read transfers
0xD: EMITRANGE = 0, sample data for write transfers. EMITRANGE = 1, sample Daddr (lower 16 bits) for write transfers
0xE: EMITRANGE = 0, sample PC + data for read transfers. EMITRANGE = 1, sample Daddr (lower 16 bits) + data for read transfers
0xF: EMITRANGE = 0, sample PC + data for write transfers. EMITRANGE = 1, sample Daddr (lower 16 bits) + data for write transfers

Note 1: If the ETM is not fitted, then ETM trigger is not possible.
Note 2: Data value is only sampled for accesses that do not fault (MPU or bus fault). The PC is sampled irrespective of any faults. The PC is only sampled for the first address of a burst.
Note 3: FUNCTION is overridden for comparators given by DATAVADDR0 and DATAVADDR1 if DATAVMATCH is also set. The comparators given by DATAVADDR0 and DATAVADDR1 can then only perform address comparator matches for comparator 1 data matches.
Note 4: If the data matching functionality is not included during implementation it is not possible to set DATAVADDR0, DATAVADDR1, or DATAVMATCH. This means that the data matching functionality is not available in the implementation. Test the availability of data matching by writing and reading DATAVMATCH. If it is not settable then data matching is unavailable.
Note 5: PC match is not recommended for watchpoints because it stops after the instruction. It mainly guards and triggers the ETM.
RW 0x0

TOP:CPU_DWT:COMP2

Address Offset 0x0000 0040
Physical Address 0xE000 1040 Instance 0xE000 1040
Description Comparator 2
This register is used to write the reference value for comparator 2.
Type RW
Bits Field Name Description Type Reset
31:0 COMP Reference value to compare against PC or the data address as given by FUNCTION2. RW 0xXXXX XXXX

TOP:CPU_DWT:MASK2

Address Offset 0x0000 0044
Physical Address 0xE000 1044 Instance 0xE000 1044
Description Mask 2
Use the DWT Mask Registers 2 to apply a mask to data addresses when matching against COMP2.
Type RW
Bits Field Name Description Type Reset
31:4 RESERVED4 Software should not rely on the value of a reserved. Writing any other value than the reset value may result in undefined behavior. RW 0x000 0000
3:0 MASK Mask on data address when matching against COMP2. This is the size of the ignore mask. That is, DWT matching is performed as:(ADDR ANDed with (0xFFFF left bit-shifted by MASK)) == COMP2. However, the actual comparison is slightly more complex to enable matching an address wherever it appears on a bus. So, if COMP2 is 3, this matches a word access of 0, because 3 would be within the word. RW 0xX

TOP:CPU_DWT:FUNCTION2

Address Offset 0x0000 0048
Physical Address 0xE000 1048 Instance 0xE000 1048
Description Function 2
Use the DWT Function Registers 2 to control the operation of the comparator 2. This comparator can emit data or PC couples, trigger the ETM, or generate a watchpoint depending on the operation defined by FUNCTION.
Type RW
Bits Field Name Description Type Reset
31:25 RESERVED25 Software should not rely on the value of a reserved. Writing any other value than the reset value may result in undefined behavior. RW 0b000 0000
24 MATCHED This bit is set when the comparator matches, and indicates that the operation defined by FUNCTION has occurred since this bit was last read. This bit is cleared on read. RW 0
23:6 RESERVED6 Software should not rely on the value of a reserved. Writing any other value than the reset value may result in undefined behavior. RO 0b00 0000 0000 0000 0000
5 EMITRANGE Emit range field. This bit permits emitting offset when range match occurs. PC sampling is not supported when emit range is enabled.
This field only applies for: FUNCTION = 1, 2, 3, 12, 13, 14, and 15.
RW 0
4 RESERVED4 Software should not rely on the value of a reserved. Writing any other value than the reset value may result in undefined behavior. RO 0
3:0 FUNCTION Function settings.

0x0: Disabled
0x1: EMITRANGE = 0, sample and emit PC through ITM. EMITRANGE = 1, emit address offset through ITM
0x2: EMITRANGE = 0, emit data through ITM on read and write. EMITRANGE = 1, emit data and address offset through ITM on read or write.
0x3: EMITRANGE = 0, sample PC and data value through ITM on read or write. EMITRANGE = 1, emit address offset and data value through ITM on read or write.
0x4: Watchpoint on PC match.
0x5: Watchpoint on read.
0x6: Watchpoint on write.
0x7: Watchpoint on read or write.
0x8: ETM trigger on PC match
0x9: ETM trigger on read
0xA: ETM trigger on write
0xB: ETM trigger on read or write
0xC: EMITRANGE = 0, sample data for read transfers. EMITRANGE = 1, sample Daddr (lower 16 bits) for read transfers
0xD: EMITRANGE = 0, sample data for write transfers. EMITRANGE = 1, sample Daddr (lower 16 bits) for write transfers
0xE: EMITRANGE = 0, sample PC + data for read transfers. EMITRANGE = 1, sample Daddr (lower 16 bits) + data for read transfers
0xF: EMITRANGE = 0, sample PC + data for write transfers. EMITRANGE = 1, sample Daddr (lower 16 bits) + data for write transfers

Note 1: If the ETM is not fitted, then ETM trigger is not possible.
Note 2: Data value is only sampled for accesses that do not fault (MPU or bus fault). The PC is sampled irrespective of any faults. The PC is only sampled for the first address of a burst.
Note 3: PC match is not recommended for watchpoints because it stops after the instruction. It mainly guards and triggers the ETM.
RW 0x0

TOP:CPU_DWT:COMP3

Address Offset 0x0000 0050
Physical Address 0xE000 1050 Instance 0xE000 1050
Description Comparator 3
This register is used to write the reference value for comparator 3.
Type RW
Bits Field Name Description Type Reset
31:0 COMP Reference value to compare against PC or the data address as given by FUNCTION3. RW 0xXXXX XXXX

TOP:CPU_DWT:MASK3

Address Offset 0x0000 0054
Physical Address 0xE000 1054 Instance 0xE000 1054
Description Mask 3
Use the DWT Mask Registers 3 to apply a mask to data addresses when matching against COMP3.
Type RW
Bits Field Name Description Type Reset
31:4 RESERVED4 Software should not rely on the value of a reserved. Writing any other value than the reset value may result in undefined behavior. RW 0x000 0000
3:0 MASK Mask on data address when matching against COMP3. This is the size of the ignore mask. That is, DWT matching is performed as:(ADDR ANDed with (0xFFFF left bit-shifted by MASK)) == COMP3. However, the actual comparison is slightly more complex to enable matching an address wherever it appears on a bus. So, if COMP3 is 3, this matches a word access of 0, because 3 would be within the word. RW 0xX

TOP:CPU_DWT:FUNCTION3

Address Offset 0x0000 0058
Physical Address 0xE000 1058 Instance 0xE000 1058
Description Function 3
Use the DWT Function Registers 3 to control the operation of the comparator 3. This comparator can emit data or PC couples, trigger the ETM, or generate a watchpoint depending on the operation defined by FUNCTION.
Type RW
Bits Field Name Description Type Reset
31:25 RESERVED25 Software should not rely on the value of a reserved. Writing any other value than the reset value may result in undefined behavior. RW 0b000 0000
24 MATCHED This bit is set when the comparator matches, and indicates that the operation defined by FUNCTION has occurred since this bit was last read. This bit is cleared on read. RW 0
23:6 RESERVED6 Software should not rely on the value of a reserved. Writing any other value than the reset value may result in undefined behavior. RW 0b00 0000 0000 0000 0000
5 EMITRANGE Emit range field. This bit permits emitting offset when range match occurs. PC sampling is not supported when emit range is enabled.
This field only applies for: FUNCTION = 1, 2, 3, 12, 13, 14, and 15.
RW 0
4 RESERVED4 Software should not rely on the value of a reserved. Writing any other value than the reset value may result in undefined behavior. RW 0
3:0 FUNCTION Function settings.

0x0: Disabled
0x1: EMITRANGE = 0, sample and emit PC through ITM. EMITRANGE = 1, emit address offset through ITM
0x2: EMITRANGE = 0, emit data through ITM on read and write. EMITRANGE = 1, emit data and address offset through ITM on read or write.
0x3: EMITRANGE = 0, sample PC and data value through ITM on read or write. EMITRANGE = 1, emit address offset and data value through ITM on read or write.
0x4: Watchpoint on PC match.
0x5: Watchpoint on read.
0x6: Watchpoint on write.
0x7: Watchpoint on read or write.
0x8: ETM trigger on PC match
0x9: ETM trigger on read
0xA: ETM trigger on write
0xB: ETM trigger on read or write
0xC: EMITRANGE = 0, sample data for read transfers. EMITRANGE = 1, sample Daddr (lower 16 bits) for read transfers
0xD: EMITRANGE = 0, sample data for write transfers. EMITRANGE = 1, sample Daddr (lower 16 bits) for write transfers
0xE: EMITRANGE = 0, sample PC + data for read transfers. EMITRANGE = 1, sample Daddr (lower 16 bits) + data for read transfers
0xF: EMITRANGE = 0, sample PC + data for write transfers. EMITRANGE = 1, sample Daddr (lower 16 bits) + data for write transfers

Note 1: If the ETM is not fitted, then ETM trigger is not possible.
Note 2: Data value is only sampled for accesses that do not fault (MPU or bus fault). The PC is sampled irrespective of any faults. The PC is only sampled for the first address of a burst.
Note 3: PC match is not recommended for watchpoints because it stops after the instruction. It mainly guards and triggers the ETM.
RW 0x0