Difference between revisions of "MTB specifics"
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= Configuration options provided by J-Link = |
= Configuration options provided by J-Link = |
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An MTB consists of the following registers / bit fields that allow configuration of the MTB and the amount of RAM it uses: |
An MTB consists of the following registers / bit fields that allow configuration of the MTB and the amount of RAM it uses: |
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+ | {| class="wikitable" |
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− | // MTB_BASE 32-bit register that specifies the base address of the MTB buffer |
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+ | !Register / Bit field |
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− | // MTB_POINTER 32-bit register that specifies the offset (rel. to BASE) where the next trace packet will be stored by the HW |
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+ | !Description |
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− | // MTB_MASTER.MASK 5-bit bitfield that specifies the wrap-around point for the auto-inc logic of the MTB, on packet store |
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+ | |- |
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+ | |MTB_BASE |
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+ | |32-bit register that specifies the base address of the MTB buffer |
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+ | |- |
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+ | |MTB_POINTER |
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+ | |32-bit register that specifies the offset (rel. to BASE) where the next trace packet will be stored by the HW |
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+ | |- |
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+ | |MTB_MASTER.MASK |
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+ | |5-bit bitfield that specifies the wrap-around point for the auto-inc logic of the MTB, on packet store |
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+ | |} |
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+ | While the MTB_BASE register is read-only for J-Link, the MTB_POINTER and MTB_MASTER.MASK can be written by J-Link. This allows the MTB RAM usage to be configured. |
Revision as of 14:11, 9 July 2018
The ARM Micro Trace Buffer (MTB) is an on-chip trace buffer that allows to do post-mortem instruction trace via a regular J-Link with no need of a specific J-Trace unit. The MTB will use a specific amount of the on-chip RAM to store trace data while the core executes instructions. MTB is mainly used on smaller MCUs like Cortex-M0+/M23/M33 based ones.
Limitations
MTB is a very limited version of trace that has the following limitations:
- Instruction trace support only
- No streaming trace possible
- A portion of the target RAM may not be used by the application if MTB is used
Configuration options provided by J-Link
An MTB consists of the following registers / bit fields that allow configuration of the MTB and the amount of RAM it uses:
Register / Bit field | Description |
---|---|
MTB_BASE | 32-bit register that specifies the base address of the MTB buffer |
MTB_POINTER | 32-bit register that specifies the offset (rel. to BASE) where the next trace packet will be stored by the HW |
MTB_MASTER.MASK | 5-bit bitfield that specifies the wrap-around point for the auto-inc logic of the MTB, on packet store |
While the MTB_BASE register is read-only for J-Link, the MTB_POINTER and MTB_MASTER.MASK can be written by J-Link. This allows the MTB RAM usage to be configured.