UART0, UART1, SPI, I2C

[mr_g]

Atmel ATmega128 has many communication interfaces. USART0 and SPI are used for PC conection (configuration, firmware upload, loging, ISP). USART1 is connected to 1wire interface over DS2480B. I2C (Two Wire Interface==SCL/SDA==I2C) has connector with no connection...

What can we use USART1/1W and TWI for? Can TWI or USART1 be used for connection to another daughter board (engine monitoring + traction controller)?

[krzycho-g]

I also join in the question whether it is run a second port to the first port to be running VEMStune and the second port AIMlogger.

[jrussell]

At this point, USART1 is only allowed to be 1wire or GPS input at 4800 baud. In general it's not used at all, so not connected to anything unless you had asked.