CORTEX-M3 DEVICE SIMULATION RESULT DIFFERS FROM REAL HARDWARE

Applies to: ARM Development Tools

Answer

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Information in this article applies to:

• MDK-ARM All Versions

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SYMPTOMS

During some tests with a Cortex-M3 beased device like toggling a general IO pin I have noticed, that the target hardware is slower than simulation.

What is the reason for this difference?

CAUSE

The Cortex-M3 simulation is cycle accurate with the following exceptions:

• memory accelerators are not simulated (zero latency is assumed)
• when executing code from system bus (like SRAM) the instruction stalls due to data R/W to system bus is not taken into account
• some combination of instruction (LDR,STR,… branch folding) can lead to reduced cycles and this is also not simulated

In general this means that simulator will show a bit faster execution.

CONCLUSION

We can say simulation will slightly differ from the hardware regarding cycles due to some Cortex-M features are not fully simulated and due to different vendor specific memory interfaces implementations which are also do not simulated.

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Article last edited on: 2010-07-21 06:06:21