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AN1176.0
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
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Copyright © Intersil Americas Inc. 2005. All Rights Reserved.
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Real Time Clock USB Evaluation Board
Introduction
This evaluation board provides a platform for testing the
ISL1208 and ISL1209 Real Time Clock (RTC) devices.
Device features include a crystal oscillator, clock and date
counters, and an alarm. The ISL1209 device includes an
event-detection feature for recording the time of an event.
The evaluation board provides a platform to test all of these
functions, as well as evaluate device performance criteria,
such as long-term clock accuracy. Hardware options such as
battery and crystal types can also be tested. The software is
designed to allow easy setup and monitoring of all major
device functions. The two-piece construction utilizing a
motherboard and a daughtercard enables the board and
software to operate the RTC device residing on a remote
board.
FIGURE 1.
Operation of the RTC Evaluation Board
Hookup and Power
CONNECTIONS
The eval board consists of a motherboard and daughtercard
and these need to be connected together. The evaluation
board uses hardware and software from FTDI for USB
communications and these drivers must be installed on each
PC that talks to the RTC eval board. A USB cable, with type
A and B connectors on the ends, is required to hook up the
board to a PC. The cable should be connected to the PC first
and then to the eval board. Once connected, LED1 will
illuminate indi5V power is available from the USB
cable.
POWERING DOWN
The daughter card contains backup power, consisting of a
battery or supercap. When powering down, the
daughtercard will operate off the backup source determined
by JP2 (after the V
CC
voltage discharges from the V
CC
supply capacitors). If the user wishes to totally power down
the RTC device once V
CC
is removed, then either remove
the daughtercard from the motherboard or set JP2 to GND.
Keep in mind there is a decoupling capacitor on the
daughtercard (0.1µF) which must discharge fully before the
RTC device stops operating. This discharge time can be up
to one second when using a V
CC
of 5V. Note that when
powered down, the RTC board cannot be monitored by the
RTC software.
Installing the RTC Software and USB Drivers
USB DRIVERS AND COM PORT SETUP
Insert the Intersil RTC_USB CDROM in the PC to be used.
Open the folder “Install USB”. Then open the ZIP file
“FTDI.zip”. Extract this set of files to a separate folder on
your main hard drive. For example, create a folder titled
“FTDI” on your C: drive, then extract the contents of the ZIP
file to that folder. In the “Install USB” folder, there is a pdf file
titled “Windows Drivers Installation Guide”. Open that file
and follow the instructions for the FTDI 232 device (you will
need to connect the RTC_USB Eval Board to your PC’s USB
port, this will bring up a prompt to install the USB hardware
and software drivers).
Note that both a hardware AND a software driver need to be
installed for correct USB operation. These are two
procedures that are best done sequentially per the FTDI
Installation Guide.
Once the USB drivers are loaded, locate the RTC program,
titled “Intersil 12xx_2.exe” on the CD. This program can be
placed anywhere on the PC, or may be run from the CD.
Double-click to execute the program (note that the “.._2”
may be changed as the program is updated and the revision
changes).
After starting the program, an error window may appear
indicating that a certain COM port is not available. Dismiss
this window by clicking “OK”. A timeout error may follow and
this should be dismissed as well.
On the Intersil RTC Data Analyzer main window, click on the
“Setup” pulldown menu. Click on “Autodetect” and the
program will search each COM port to find which is
connected to the USB device on the eval board. A small
“COM Auto Detect” window will appear and monitor the
polling process. Once the correct COM port is detected, it is
noted in the “COM Auto Detect” window and that window will
close. If you wish to review which COM port is being used,
just click again on the “Setup” pulldown menu.
If no COM port is detected, make sure the board is
connected to the PC with a USB cable and that the board
jumpers are in the appropriate places (see hardware
section). If there is still no COM port detected after any
Application Note
June 20, 2005
