68HC05K0 Infra-red Remote Cont

The MC68HC05K0 is a low cost, low pin count
single chip microcomputer with 504 bytes of user
ROM and 32 bytes of RAM. The MC68HC05K0 is
a member of the 68HC05K series of devices which
are available in 16-pin DIL or SOIC packages.
It uses the same CPU as the other devices in the
68HC05 family and has the same instructions and
registers. Additionally, the device has a 15-stage
multi-function timer and 10 general purpose
bi-directional I/0 lines. A mask option is available
for software programmable pull-downs on all of
the I/O pins and four of the pins are capable of
generating interrupts.
The device is ideally suited for remote-control
keyboard applications because the pull-downs and
the interrupt drivers on the port pins allow
keyboards to be built without any external
components except the keys themselves. There is
no need for external pull-up or pull-down resistors,
or diodes for wired-OR interrupts, as these features
are already designed into the device.