User guide

53
SmartBook for Renesas R8C/Tiny Microcontrollers
www.MightyMicons.com
Analog to Digital Converter.
INT2.
UART1 Transmission.
UART0 Transmission.
Key Input. Lowest Priority Level.
5.5.3 External Hardware Interrupts.
R8C/Tiny controllers have many external hardware interrupts, which can sense
uncertain events in the target applications. They are known as INT interrupts,
from INT0 to INT3. Like other interrupts, each of these interrupt is supported with
an interrupt control register along with few other support registers. They also have
facility to select the trigger polarity.
Apart from all the above, these hardware interrupts are supported with input filters
to avoid false interrupts. These filters wait and watch the presence of the interrupt
pulse for a selected time. The interrupt calls are taken as the genuine only when
the interrupt pulse stays stable for a predefined time. There is a facility to select
this filtering time using three different frequencies.
These hardware interrupts lines are combined with timer/ counter lines to keep
the chip pin count low. So, proper initialization is required to get these interrupt
lines working in any application.
5.5.4 Interrupts for Keyboard and Switches.
This is a welcome feature with the R8C/Tiny micons to simplify
the interfacing of a matrix keyboard and keys or switches
with the device. As you know, the keys and switches
are vital elements in any embedded application.
There are four interrupt lines available to connect
keys and switches. These interrupts can be
made to act upon either falling or the rising
edge and all these interrupts share a
common service routine. In the routine, the
application should determine exactly which
interrupt has been called for. These
D
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4
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Interrupts
for Keyboard and
Switches is a welcome
feature with the R8C/Tiny
micons to simplify the interfacing
of a matrix
keyboard or
individual keys or
switches with the
device.