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HANDS-ON MICROCONTROLLERS
40
Figure 4. You can actively program an R8C via the Internet.
Level 1: On the hardware side, the simplest option only
requires a level converter for the RS232 interface, as previously
mentioned, and a serial interface cable. To that
you can add the free Renesas NC30 compiler with its
integrated development environment (HEW).
Although the compiler is restricted to 64 KB, that does
not impose any restriction on projects using the R8C,
since it can anyhow only address a maximum of 64 KB.
Besides C projects, it’s also possible to develop assemblylanguage
programs. The debug output format is
IEEE 695.
The HEW program or the KD30 program (also free of
charge) can be used for debugging. Code generated by
Figure 5. And experimental prototype circuit using the R8C/13 board.
This circuit will be presented in the February 2006 issue.
the GNU C compiler can also be debugged using this
tool. All you have to do is to change the debug format to
IAR/ELF Dwarf2. You can use Flashstart or FDT to flash
the finished application into the microcontroller.
Level 2: If you want to perform debugging using a synchronous
serial interface, independently of the crystal frequency
and without using a monitor, you need Renesas’s
smallest hardware debugger, the model E8 (Figure 3).
For the duration of this series of articles, it can be
obtained from Glyn GmbH & Co. KG at a special price
of €110 (ex VAT) instead of the regular price of €150.
The E8 can generate breakpoints at data location as well
as addresses, and it supports genuine real-time program
execution and extended trace levels. The PCB pads for
connecting this tool are already present in the free area
of the circuit board described in the December issue. All
you have to add is a few header pins.
The integrated development environment (HEW) is also
used for debugging at this level, because it is the only
one that supports the E8. Here again, either the NC20
compiler or the GNU C compiler can be used. Flashstart
or FDT can then be used to flash the finished application
into the microcontroller.
Level 3: For professional software development, R8C
software can also be debugged using the Renesas
PCC7501 real-time emulator, which naturally comes at a
higher price. The PC7501 is connected to an emulation
probe and provides countless features for searching for
errors. It can measure program execution times and
record the individual steps executed before a bug. It can
also record digital signals from the application circuit ‘on
the side’ with a resolution of 1 µs.
The outlook
If your curiosity has been aroused by now, you can
already start doing a few ‘preliminary exercises’ with the
R8C. The www.renesasinteractive.com website is a good
resource for this. There you can even program a genuine
starter kit via the Internet (see Figure 4), and you can
naturally learn more about the features of the R8C. The
only software you need to have installed on your computer
for these functions is a web browser. The NC30,
NEW and KD30 programs run entirely on the remotely
controlled computer.
Besides this, you can also use your own computer to
check whether specific tasks can be handled using this
microcontroller. However, that does require installing a
few programs before you start (see inset). It must be
admitted that the necessary software takes up a certain
amount of space and requires some familiarisation. Naturally,
all of the programs will be provided on the software
CD-ROM available from Readers Services, and detailed
installation instructions will also be provided with the programs.
All of that will be topped off with simple projects to make
your first steps with the R8C/13 even easier. Figure 5
shows an experimental prototype of a circuit
planned for the February 2006 issue. It doesn’t
require much more than a voltage regulator and a pair of
transistors for the serial interface!
(050179-1)
elektor electronics - 1/2006