The XC-2285A acts as a communication link between
the XU-i088 and a PC and/or other XU-i088 single board computers.
One example is to link the XU-i088 to a PC. This enables the user
to monitor and/or control the on board digital I/O of the XU-i088
and other devices on the XCI expansion boards from the PC.
If an EEPROM is installed on the ROM socket
of the XU-i088, the user can even download programs from the PC to
the XU-i088 via the XC-2285A communication I/F.
Real time clock (RTC)
A 3287A Real-Time Clock (RTC) module is included on
the XC-2285A. The 3287A is a low power microprocessor providing a
time-of day clock and one hundred years with battery operation.
The 3287A also equipped 114 bytes of general nonvolatile
storage, they can be used to stored the XU-i088 configuration and
status even the power is turn off.
The 3287A RTC module equipped with a 3V Lithium battery,
this battery is used to stored the 114 byte memory and keep the clock
operating during the power off. The Lithium battery will operate the
3287A at least 10 years during the power is off.
An 8254 timer is included on the XC-2285A. The 8254
is included on the XC-2285A to supplement the XU-i088. Since the XU-i088
does not have a timer to generate accurate time delays for certain
applications, the application may use the 8254 timer on the XC-2285A.
This counter/timer chip can be programmed to create accurate time
There are several different modes of operation for
the 8254. Each has its advantage over the others under certain circumstances.
There are four interrupts from the XC-2285A, each interrupt
has different purpose, they are RTC interrupt, Communication
RX interrupt, Timer 1&2 interrupt and Timer 0 interrupt.
The RTC alarm INT can be used in a very wild purpose, for
example, you may set the RTC interrupt to be in forced a
The communication RX INT interrupt the XU-i088's CPU when the
communication data is being received. This is provided so
that the XU-i088 can always "listen" for incoming data or
The Timer 0 INT can be used as the a system interrupt.
A beeper is also provides by the XC-2285A. The frequency
of the BEEPer is determined by the 8254 Timer 1 OUT or the timer 1
& 2 OUT. If the BEEPer is used, then the Timer 1 & 2 INT should be