ETAS
Hardware Description
FETK-T3.0 - User’s Guide
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4.8
Data Access
4.8.1
Calibration Data Access
The FETK-T3.0 is a serial FETK using JTAG and Aurora trace the microcontrol-
ler interface. Typical of all serial ETKs, XETKs and FETKs, the RAM used for
data emulation and data measurement is not accessible by the FETK until the
microcontroller is powered up and the startup handshake is performed.
Serial FETKs use the ETAS two page concept, consisting of both a Reference
and a Working page.
The Reference Page is located in the ECU flash and can not be modified by a
simple write access. All changes to the Reference Page must be done via Flash
programming.
The Working Page is located within the microcontroller's EMU RAM. The Work-
ing Page may be a portion of or the entire size of the EMU RAM. The EMU RAM
used for the emulation of calibration data must not be used by the ECU soft-
ware directly as general purpose RAM. It is recommended that the EMU RAM is
permanently powered by the FETK-T3.0 or ECU and shall not be reset by the
ECU, if the FETK-T3.0 signals a permanently powering of the EMU RAM during
handshake.
The FETK / INCA has complete control over the RAM used as Working Page
and it's contents. When enabling data emulation, the FETK establishes a basic
start-up configuration of the data in the Working Page by copying the corre-
sponding data in the Flash to the emulation space.
To enable calibration, the Working Page must be activated. The process of
switching from the Reference Page to the Working Page and vice versa is
known as page switching.
The FETK-T3.0 supports Protocol Based page switching for all supported
microcontrollers. Page switching is done in microcontroller software by switch-
ing the overlay memory on (Working Page) and off (Reference Page) using
microcontroller overlay registers. The FETK-T3.0 does not directly control the
microcontroller overlay registers. Instead the FETK-T3.0 and microcontroller
software use a simple communication method with a shared mailbox in RAM.
The FETK-T3.0 uses this mailbox to request and monitor page switching; the
microcontroller software is responsible to service this mailbox and perform the
page switches. Using an overlay modification description, also in RAM, the
FETK-T3.0 provides the necessary information.
The FETK-T3.0 can access both the Reference Page and the Working Page,
regardless of which is active from the microcontroller’s point of view.
Another important restriction is that no access to the memory is possible, while
the ECU is not running. To enable a cold start measurement in spite of this
restriction, the cold start measurement procedure is defined to give the user
the feeling of a parallel FETK.
