MATLAB REAL-TIME WORKSHOP EMBEDDED CODER - S Bedienungsanleitung PDF herunterladen (Seite 23)

4 Analysis of the Generated Code

4.1 Memory Usage RAM, ROM and Execution Time

To make a comparison between the generated code and the hand written code, the

system is built for host and target with the generated code from both TargetLink

and the code generated from Real-Time Workshop Embedded Coder. Memory

usage and execution time are calculated. The tables below show the execution

times, RAM and ROM memory usage. The tested program code is the code for

the pressure controller including a PID controller. See Appendix IV The Model.

The hand written code in Haldex base software was replaced by the generated

code and a model was built and run on a C166 microprocessor as a target. Many

tests were carried out while running on the target to see if the controller behaves

as expected. ROM and RAM memory usage were calculated after the whole

model was built. ROM and RAM memory usage were saved in a map file.

The generated code that was used in the tests is ANSI-C code when generated

with TargetLink and optimised for Infineon C16x, XC16x when generated with

RTW EC.

Pressure Controller

& PID

TargetLink

(bytes)

Real-Time Workshop

Embedded Coder

(bytes)

Hand-written

Code (bytes)

ROM

1594 2676 2282

RAM

31 2 52

Table 2: RAM and ROM memory usage

It should be mentioned here that calibrated parameters were not chosen in RTW

EC. The use of calibrated parameters in RTW EC was not investigated in this

work due to lack of time. This can be why RTW EC gives less RAM memory

usage than TargetLink as shown in Table 2 above. However, for future studies the

option Inline Parameters should be investigated.

The generated code from TargetLink uses functions for all saturation checks in the

whole code while RTW EC uses if-sets in every saturation checking everywhere

in the code. This makes the RTW EC code less efficient and that is one of the

reasons for the memory usage differences between TargetLink and RTW EC as

shown in Table 2 above. An example of this is the following code which is

generated for the same block:

1 2 ... 18 19 20 21 22 23 24 25 26 27 28 ... 75 76

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