Copyright
©
Kanda 2013
6
Pop-up Warnings
This displays a message box if there is a verify error. Useful if repeated Auto Program
operations are carried out, when it can be easy to ignore errors.
Setup
This can also be selected by clicking the Setup Button. It covers a variety of settings,
which are not needed on STK300 board, except Communications Device. This is
needed if you have multiple parallel ports when you should select the correct LPT port.
The other settings are mostly for use on your own circuits, and are described on the
screen.
Reset Button
This is used to Reset the AVR on the board. This is a way of resetting communications if
errors occur or the programmer cannot find the chip.
STK300 Board Description
The schematics of the board are available in the Documentation > STK300 folder on the
CD.
Voltage Selection
There is one jumper – JP1 – for setting the board voltage. If the jumper is on, the board
operates at 5V. If it is off, the board operates at 3.3V.
Notes:
1) If the board is set to 3.3V, the brownout circuit should be set to 2.9V by removing
JP2
2) The ISP interface is supplied with 5V regardless of the board voltage.
3) The Atmega128L supplied as standard can operate from 2.7-5.5V
Brownout Circuit
The STK300 has a brownout detector to reset the AVR if the voltage drops too low. The
brownout level is set using JP2 and should match the voltage selected by JP1 i.e. JP1
and JP2 both off or both on.
Clock Circuit
The board uses an 8MHz crystal connected to a 74HC00 external clock chip. The clock
signal is connected to XTAL1 pin on Atmega128.
Serial Ports
The Atmega128 has two hardware USARTs. Both are connected through a MAX202
chip to give RS232 level signals.
USART0 (RXD0/TXD0) is connected to the female 9-way D-Type connector.
USART1 (RXD1/TXD1) is connected to a 2-way pin header, labeled COM2.
Both USARTs are also available, at TTL levels, on the expansion headers on the edge
of the board (UART0 on PE0, PE1 and UART1 on PD2, PD3)
Details about Baud Rates, control and other settings are in Atmega128 datasheet.
