C8051F99x
Rev. 0.2
15
5.5. Switches and LEDs (J1, J5, J8, J15, J16, SW1, SW2, SW3)
Three push-button switches are provided on the target board. Switch SW1 (RESET) is connected to the reset pin
of the C8051F996. Pressing SW1 puts the device into its hardware-reset state. Switches SW2 (P0.2) and SW3
(P0.3) are connected to the C8051F996’s general purpose I/O (GPIO) pins through headers. Pressing SW2 or
SW3 generates a logic low signal on the port pin. Remove the shorting block from the header (J8) to disconnect the
switches from the port pins. The port pin signal is also routed to pins on the J2 and P1 I/O connectors. See Table 1
for the port pins and headers corresponding to each switch.
Two touch sensitive (contactless) switches are provided on the target board. The operation of these switches
require appropriate firmware running on the C8051F996 MCU that can sense the state of the switch.
Four power LEDs are provided on the target board to serve as indicators. The 3.3 V regulator has a red LED used
to indicate the presence of power at the output of the regulator. A red USB Power LED turns on when a USB cable
is plugged into the USB connector P3. One power LED is also added to each of the two primary supply nets
powering the MCU (VDD and PWR). The PWR net is before the power measurement header and the VDD net is
after the power measurement header. The LEDs connected to the supply nets may be disabled by removing the
shorting blocks from J1 and J5.
Two LEDs are connected to GPIO pins P1.5 and P1.3 for use by application software. See Table 1 for the port pins
and headers corresponding to each LED.
A potentiometer (R15) is also provided on the target board for generating analog signals. Place a shorting block on
J16 to connect the wiper to P0.6/CNVSTR. The header J15 allows the negative terminal of the potentiometer to be
tied to GND or to P1.4. When tied to GND, the potentiometer is always enabled and will draw a measurable
amount of supply current. When tied to P1.4, it only draws current when P1.4 is driving a logic 0 and draws no
current when P1.4 is driving a logic 1.
Table 1. Target Board I/O Descriptions
Description
I/O
Header(s)
SW1
Reset
none
SW2
P0.2
J8[5–6]
SW3
P0.3
J8[7–8]
P1.0 (Touch Sense Switch)
P1.0
none
P1.1 (Touch Sense Switch)
P1.1
none
Red LED (P1.5)
P1.5
J8[1–2]
Yellow LED (P1.3)
P1.3
J8[3–4]
Red LED (VDD)
VDD Supply Net
J5
Red LED (PWR)
PWR Supply Net
J1
Red LED (USB Power)
USB VBUS
none
Red LED (+3 VD Power)
+3 VD Regulator Output
none
Potentiometer (R15)
P0.6/P1.4
J15, J16
Summary of Contents for C8051F983-GM
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