5.3.2 User Push-Button Switches
For user input/control, there are eight push-button switches on the EZ-KIT Lite board:
RESET, FLAG 0-3 , and IRQ 0-2 .
• The RESET switch lets you initiate a power-on reset to the DSP. If the user
loses contact between the EZ-KIT Lite board and the PC while running
programs, use the RESET button to restore communication.
• The FLAG 0-3 switches toggle the status of four flag pins (FLAG 0-3 ) to the
DSP.
• The IRQ 0-2 switches let you send interrupts (IRQ 0-2 ) to the DSP. This
manually causes interrupts when executing a program. IRQ0 is shared with the
UART, and IRQ1 is shared with the EMAFE connector.
See “Flags” section in Chapter 3, for more information on interfacing to the push-button
switches from DSP programs.
5.3.3 User LED’s
There are six flag LEDs on the EZ-KIT Lite board for user output that are available. The
FLAG 4-9 LEDs are controlled by the FLAG outputs of the DSP and are labeled
according to the flag output that controls them. See “Flags” section in Chapter 3 for
more information on interfacing to the user LEDs from DSP programs.
5.3.3.1 Power LED
The Power LED, when on, indicates that +3.3V DC , used by the DSP and
digital circuitry, is present.
5.4 Power Supplies
ADP3310s generate the 3.3V and 5V power required by the board. These parts are linear
regulators that also regulate current. The resistor placed between the Vin and IS pins limits the
amount of current through the device. The resistance (
R s
) needed for a given maximum output
current (
I o
) is determined with the equation below.
R
s
= 0.05/(1.5
χ
I
o)
Power regulation is done through a P-channel FET. To help disperse the heat from the FET a
heatsink is attached to the drain. Note that the regulated voltage is available on the heat-sink,
since the voltage is regulated from the drain of the FET.
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