Hardware Description
3-2
AVR STK500 User Guide
1925C–AVR–3/03
Figure 3-2.
Implementation of LEDs and LED Headers
Note:
The AVR can source or sink enough current to drive a LED directly. In the
STK500 design, a transistor with two resistors is used to give the same amount
of light from the LED, whatever the target voltage (VTG) may be and to turn off
the LEDs when VTG is missing.
3.2
Description of
User Switches
The switches connected to the debug headers are implemented as shown in Figure 3-3.
Pushing a switch causes the corresponding SWx to be pulled low, while releasing it will
result in VTG on the appropriate switch header connector. Valid target voltage range is
1.8V < VTG < 6.0V.
Figure 3-3.
Implementation of Switches and Switch Headers
Note:
In the AVR, the user can enable internal pull-ups on the input pins, removing the
need for an external pull-up on the push-button. In the STK500 design, we have
added an external 10K pull-up to give all users a logical “1” on SWn when the
push-button is not pressed. The 150R resistor limits the current going into the
AVR.
LED1
LED3
LED5
LED7
VTG
LED0
LED2
LED4
LED6
GND
1 2
LEDn
10K
VTG
+5V
150R
10K
150R
VTG
SWn
SWn
SW1
SW3
SW5
SW7
VTG
SW0
SW2
SW4
SW6
GND
1 2
Содержание AVR STK500
Страница 1: ...STK500 User Guide ...
Страница 2: ......
Страница 38: ...Hardware Description 3 28 AVR STK500 User Guide 1925C AVR 3 03 ...
Страница 40: ...Installing AVR Studio 4 2 AVR STK500 User Guide 1925C AVR 3 03 ...
Страница 52: ...In System Programming of an External Target System 6 2 AVR STK500 User Guide 1925C AVR 3 03 ...
Страница 56: ...Technical Support 8 2 AVR STK500 User Guide 1925C AVR 3 03 ...
Страница 60: ...Appendix A 10 2 AVR STK500 User Guide 1925C AVR 3 03 ...