An on-chip I2C bus is included to provide a standard communication interface for digital audio applications. I2C is a three-wire serial bus using one data line, clock line, and word select signal. The I2C interface on the LPC2300 and LPC2400 provides a separate transmit and receive channel, each of which having the ability to operate as a master or slave. Additional standard serial communication interfaces include three I2C, two SPI, or SSP (buffered SPI) and four 16C550-type UARTs that include a fractional baud rate generator, auto-baud, and hardware flow control.