User manual

RSKR8CLA8A 5. User Circuitry
R20UT0284EG0101 Rev. 1.01 Page 14 of 34
Jun 16, 2011
5. User Circuitry
5.1 Reset Circuit
The RESET pin is connected to Board_VCC via a pull-up resistor R33. When
the VCC pin voltage level rises, the
power-on reset function is enabled and the pins, CPU, and SFRs are reset
. Refer to the R8C/LA8A hardware manual
for details regarding the reset signal timing requirements, and the RSK R8C/LA8A board schematics for
information regarding the reset circuitry in use on the RSK.
5.2 Clock Circuit
Crystal oscillators are fitted to the RSK to generate the required clock signal to drive the MCU, and associated
peripherals. Refer to the R8C/LA8A hardware manual for details regarding the clock signal requirements, and the
RSK R8C/LA8A board schematics for information regarding the clock circuitry in use on the RSK. Details of the
oscillators fitted to the RSK are listed in Table 5-1 below.
Crystal Function Default Placement Frequency Device Package
X1 Main MCU oscillator. Fitted 20MHz HC49/4U
X2 Internal RSK Testing Only Unfitted n/a n/a
X3 Real time Clock Fitted 32.768kHz Encapsulated, SMT
Table 5-1: Oscillators
5.3 Switches
There are four switches located on the RSK board. The function of each switch and its connection is shown in
Table 5-2. For further information regarding switch connectivity, refer to the RSK R8C/LA8A board schematics.
Switch Function MCU Connection
RES When pressed, the microcontroller is reset. RESETn, Pin 9
SW1 Connects to an IRQ input for user controls. INT1n, Pin 20 (Port 8,
bit 0)
SW2 Connects to an INT input for user controls.
The switch is also used as wake up signal when connected to MCU pin
WKUP0n (Pin 4) via option jumper resistor R39.
INT2n, Pin 3 (Port 8,
bit 7)
SW3 Connects to an INT input for user controls. The switch is also connected
to an ADTRGn input (Pin 66) via option link resistor R41 and R76, and is
used to trigger AD conversions.
INT3n, Pin 19 (Port 8,
bit 1)
Table 5-2: Switch Connections