C 8 0 5 1 T 6 2 0 / 2 - D K
14
Rev. 0.5
7.1. System Clock Sources
The C8051T62x/32x devices feature a calibrated internal oscillator that is enabled as the system clock source on
reset. After reset, the internal oscillator operates at a frequency of 48 MHz (±1.5%) by default but may be
configured by software to operate at other frequencies. Therefore, in many applications, an external oscillator is not
required. However, if you wish to operate the C8051T62x/32x device at a frequency not available with the internal
oscillator, an external oscillator source may be used. Refer to the C8051T620-21-26-27_T320-3 or C8051T622-
23_T326-27 data sheet for more information on configuring the system clock source.
7.2. Switches, LEDs, and Potentiometer (J9, J10, and J12)
Three switches are provided on the motherboard. The RESET switch is connected to the RST pin of the
C8051T62x/32x. Pressing RESET puts the device into its hardware-reset state. The switch labeled “SW1” can be
connected to the C8051T62x/32x's general-purpose I/O (GPIO) pins P0.1 and P2.0, and “SW2” can be connected
to the C8051T62x/32x's general-purpose I/O (GPIO) pins P1.0 and P2.1 through header J9. Pressing a switch
generates a logic low signal on the port pin. Remove its shorting block from the J9 header to disconnect the switch
from the port pin.
Seven LEDs are also provided on the motherboard. The red LED labeled “PWR” (D4) is used to indicate a power
connection to the motherboard. The green LED labeled “RUN” (D10) turns on when the debug circuitry is in a
running state; the red LED labeled “STOP” (D11) turns on when the debug circuitry is in a halted state, and the
orange LED labeled “DEBUG PWR” (D12) indicates whether the debug adapter circuit is being powered through
P5's USB connector. The red LED labeled “VPP” (D7) indicates when the VPP programming voltage is being
applied to the device. The green LEDs, labeled “LED1” (D1) and “LED2” (D2), can be connected to C8051T62x/
32x's GPIO pins through header J10. Remove its shorting block from the header to disconnect an LED from the
port pin. The red LED labeled “USB ACTIVE” (D13) will turn on whenever the CP2103 USB-to-UART bridge is
connected to a PC and has successfully completed enumeration.
Also included on the C8051T62x Motherboard is a 10 k
thumbwheel rotary potentiometer, reference number R8.
The potentiometer can be connected to the C8051T62x/32x's P2.5 pin through the J12 header. Remove the
shorting block from the header to disconnect the potentiometer from the port pin.
Not
Recommended
for
New
Designs
