FEBRUARY 2006 £3.80 - Index of

nections that are essential for a ‘quick
start’, so you can get your bearings as
fast as possible. The connections not
shown in the figure must always
remain open. Figure 4 shows an experimental
setup on a prototyping board.
The serial port of the PC is connected
here via transistor inverters. Although
a MAX232 could be used just as well
for this purpose, the transistors will
probably be easier to find in your parts
bin. A BC548C NPN transistor inverts
the TXD signal from the PC and feeds
it to the RXD1 input of the microcontroller.
This input does not have an
internal pull-up, so the collector resistor
is essential. In the opposite direction,
TXD1 drives a BC558C PNP transistor.
The RXD input of the PC has its own
pull-down, so the collector resistor can
be omitted here.
The MODE input of the microcontroller
determines whether the internal
boot program or a downloaded
user program is run after a reset. The
MODE input is pulled high by a 10-kΩ
resistor when the switch is open,
which causes the user program to be
started. If you want to load a program
into the flash memory, you first have
to close the switch in order to pull
MODE low. Then you must briefly
press the Reset switch. That causes
the microcontroller to start up in the
debug mode, which allows new software
to be loaded into the flash ROM.
After the software has been transferred,
open the Mode switch and
press the Reset switch again. That
causes the downloaded program to be
started. However, duty comes before
pleasure, and in this case the duty is
installing the software on the PC.
That’s described step-by-step in the
inset. Follow the instructions exactly
as given in order to ensure that what
you later see on your PC matches
what we describe here.
Ready, set, flash!
The first thing you should do is to try
out the Flash Development Toolkit
(FDT) by downloading a finished program
to the microcontroller. For the
time being, we’ll skip the process of
developing you own programs, so you
can enjoy some tangible results as
soon as possible.
After installing the Renesas software
package, you will find the FDT program
in the Windows ‘Start’ menu. The
program is shown there in two versions:
a full version and a compact
Figure 4. A prototype of the test system built on a lab prototyping board.
‘Basic’ version. Start ‘Flash Development
Toolkit Basic’ (Figure 5).
You must configure several settings
the first time you start the program.
If necessary, you can access them
later on via the Options / New Settings
menu. Select ‘R5F21134’ as the
microcontroller type, and select the
upper of the two core protocol options
(Figure 6).
In the next window, select the serial
interface port from the range
COM1–COM4. The third window asks
you to specify a baud rate for the link
to the microcontroller. Enter ‘9600
baud’ here (Figure 7).
Finally, you have to specify whether
you want to enable readout protection
for the microcontroller. As the risk of
criminal industrial espionage is rather
small with the initial familiarisation
programs, you can dispense with any
form of protection. Save the settings as
shown in Figure 8. That completes the
preparations.
Hurrah, it blinks!
Now connect the board to the specified
COM port on your PC. Close the Mode
switch and briefly press the Reset
switch. The microcontroller will enter
boot mode and wait for you to send it
data.
The next step is to download a fully
compiled program to the microcontroller.
On the CD, you will find the
‘Sample NC30’ folder with several sample
projects. That includes the project
folder ‘Sample_NC30\ port_toggle’,
which contains the folder ‘port_toggle\
Release’. The file port_toggle.mot is
located in the latter folder. It is a program
in Motorola hex format that can
be downloaded directly to the microcontroller.
Specify the path to this file, and then
start the download process by selecting
‘Program Flash’. The download
takes around two seconds. The flash
memory is first erased, and the new
program is then copied over. If everything
goes properly, the message
‘Image successfully written to device’
will be displayed. Open the Mode
switch and briefly press the Reset
switch. That will start the program
that you just downloaded.
The program toggles the first four
lines of Port 1 (P1_0 to P1_4) at a slow
rate, so you can observe their states
using a LED with a series resistor. The
ports of the R8C and the other M16
microcontrollers have a low impedance
in the output direction, regardless
of whether they are in the high or
low state. That means you must
always use a series resistor (1 kΩ, for
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