See also
Port Connectors
for more information about the AUX header.
Other Considerations
High-Voltage Programming
When programming the target AVR in High-Voltage programming mode, the clock settings is overridden and the device is clocked directly from the
STK600 controller. The clock selection switch can be set to any position.
On-chip Crystal Oscillator
In a real-life application where the crystal can be placed close to the AVR's XTAL1 and XTAL2 pins, there is no need for an external oscillator
circuit. The long clock signal lines and socket system connectors on STK600 makes it difficult to drive a crystal with the on-chip oscillators. This is
resolved by having a crystal oscillator on STK600. The oscillator is designed to operate over the full target voltage range.
Shared XTAL1/Port Pin
Some AVR devices have a XTAL1 pin which also can be used as a regular I/O port pin. The routing card for these devices will connect the device
pin to both the XTAL1 net and a port pin header on the STK600. Hence, to use the pin as a I/O port the clock selection switch must be set to
position INT to disconnect the clock drivers on STK600 from the pin.
User RS232 Interface
The STK600 includes a RS232 hardware that can be used for communication between the target AVR microcontroller in the socket and a PC serial
port. STK600 has a 9-pin DSUB connector that can be connected to a PC with a straight serial cable (not a null modem cable).
To use the RS232 interface, the AVR's UART pins must be connected to the appropriate pins on the "RS232 SPARE" pin header. Use a 2-wire
cable to connect the AVR's RXD and TXD pins to the pin header. The "RS232 SPARE" pin header is found in the target header section, while the
DSUB marked "RS232" is located on the other end of the card.
Optionally one can connect the RTS (Request To Send) and CTS (Clear To Send) signals to two free I/O ports. The RTS and CTS signals are used
for flow control. The connection is shown below.
Page 21 of 35
STK600 User Guide
2008-06-20
file://C:\Documents and Settings\PAWEL\Ustawienia lokalne\Temp\~hhE369.htm
