Fast Models Reference Manual - ARM Information Center

Emulation Baseboard Model: Platform and Components
7.9.6 GPIO2
On the EB hardware, GPIO2 is dedicated to USB, a push button, and MCI status signals. USB
and MCI are not implemented in the EB RTSMs, and no push button is modeled. The GPIO is
therefore simply provided as another generic IO device.
7.9.7 Timing considerations
The Real-Time System Models provides an environment that enables running software
applications in a functionally-accurate simulation. However, because of the relative balance of
fast simulation speed over timing accuracy, there are situations where the models might behave
unexpectedly.
If your code interacts with real world devices like timers and keyboards, data arrives in the
modeled device in real world, or wall clock, time, but simulation time can be running much
faster than the wall clock. This means that a single keypress might be interpreted as several
repeated key presses, or a single mouse click incorrectly becomes a double click.
To work around this problem, the EB RTSMs supply the Rate Limit feature. Enabling Rate
Limit, either using the Rate Limit button in the CLCD display, or the rate_limit-enable model
instantiation parameter, forces the model to run at wall clock time. This avoids issues with two
clocks running at significantly different rates. For interactive applications, ARM recommends
enabling Rate Limit.
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