Developing embedded systems, Setting up software environment – SDCC

11 09 2008

Please note: This is copied from my personal wiki for documentation. Few parts are copied from web and may have a few typo.

Introduction

Traditionally the bulk of development on PICs, both by professionals and enthusiasts, has been done in assembly language. In part this was due to performance requirements, and part due to the lack of any real alternatives. However, with the increase in the power of available PICs and the availability of several high level languages for PICs, it is becoming increasingly appropriate to consider HLLs for PIC projects.

While C compilers have been available to professional programmers for some time, their cost has limited their use by enthusiasts. Now, through the open source development model, free tools are becoming available.

Here I have used such a tool called SDCC (Small Device C Compiler). SDCC supports both 14 and 16 bit core PICs, here we will configure both, but will use 14 bit as our project will use PIC16F series.

I shall use PikDev IDE for coding and gpsim for simulating the code. These will come later.

Software Requirement

I shall discuss only sdcc here. Others will follow in later posts.

  • SDCC 2.8.0
  • gputils 0.13.5 beta
  • gpasm 0.22.0
  • gpsim

SDCC toolchain

SDCC does not operate in isolation, and when targeted on PIC devices it makes use of the gputils tools to provide the back end of the compilation process. The simplest tool chain is shown below.

Sdcc_tool_chain.jpg

Installing SDCC

Due to sdcc’s constant development, it is best to build it from the sources rather than to install a pre-built binary package which will very quickly become out of date.

Checking GCC

  • Firstly gcc is to be checked.
$ gcc -v

gcc version 4.3.0 20080428 (Red Hat 4.3.0-8 ) (GCC)

Download Source

  • The source (sdcc-src-2.8.0.tar.bz2) can be downloaded from sourceforge.net. The link is here.
  • I tried the rpm from fedora repo. It makes a executable named “sdcc-sdcc”. Buildng from source, however

Compile SDCC

  • Compiling sdcc from the source code is easy. We will remove the features we don’t want and configure it for our purpose.
  • In the top level of the source tree run this:
./configure --disable-mcs51-port --disable-gbz80-port --disable-z80-port \
--disable-avr-port --disable-ds390-port -disable-ds400-port --disable-hc08-port \
--disable-xa51-port

Run make.

Building PIC16 libraries

The next step is to build some function libraries that come with sdcc. The next few command will build these.

This will install the pic16 libraries.

cd <sdcc_src>/device/lib/pic16
make libio
su -c “make install”

Building PIC14 libraries

Now we will make the pic14 libraries.

cd <sdcc_src>/device/lib/pic
configure
make
make install # moves libs to device/lib/build/pic... or so

Installing everything

Now we move to upper directory

cd ..        # now you are in device/lib
make install # to move the library into an -I'ncluded path

And we’re done building sdcc.

SDCC detailed tool chain

Sdcc_tool_chain_details.jpg

Now we can compile our c programmes using sdcc.

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