Calibration

Calibration is the process of adjusting and optimizing the parameters in an Electronic Control Unit (ECU) to fine-tune its behavior.

The M-ETK is a high-performance hardware interface that acts as a bridge between your computer, running a calibration software like ETAS INCA, and the vehicle's ECU. It provides a fast and reliable communication link, enabling you to not only read measurement data from the ECU but also to write new values to it.

The M-ETK uses standardized XCP (Universal Measurement and Calibration Protocol) for all functionalities.

The effect of the changes can be observed in real-time by monitoring the measurement data in parallel.

Advanced Calibration: The Two-Page Concept with Overlay Memory

To allow for safe and flexible calibration, the M-ETK supports the "Two-Page" memory concept, which relies on a feature in the microcontroller (µC) called "Overlay Memory."

Imagine you have two identical sets of calibration data:

• Reference Page (RP): This is the original, safe set of parameters. It is stored in the ECU's non-volatile Flash memory. Think of this as your "factory settings" or the last known good configuration.

• Working Page (WP): This is a copy of the parameters stored in a fast, volatile RAM area. This is the page you actively modify during a calibration session.

This provides two major benefits:

• Safety: You can experiment freely in the Working Page. If a change leads to undesirable behavior, you can simply switch back to the stable Reference Page.

• Persistence: The changes made in the Working-Page are temporary because they are in RAM. Once you are satisfied with your new calibration, you can permanently save the data from the Working Page back into the Flash memory if the ECU flashing feature is available for the M-ETK.

The Overlay Memory functionality is a hardware feature of the µC that allows the ECU to seamlessly switch between these two pages. When you start a calibration session with a tool like INCA, the system activates the overlay memory. Any time the ECU's software tries to read a calibration parameter from the non-volatile Flash memory (the Reference Page), the overlay memory feature intervenes. It redirects the request automatically to the corresponding address in the RAM (the Working Page). This allows you to make changes in the Working Page and see their effect instantly without altering the original, safe data in the Flash.

Overlay Memory Descriptor (OMD)

To setup the overlay memory feature in the µC an OMD is used. The OMD contains the memory regions used as working page, reference page, and the respective sizes. This allows you to make changes in the Working Page and see their effect instantly without altering the original, safe data in the Flash.

One Page Concept

If no overlay controller is available a single page concept can be used for calibration or an ECU SW supported pointer-based calibration method.