SC18IS604 SPI to I2C-Bus Bridge NXP Semiconductors SC18IS604 SPI to I2C-Bus Bridge is designed to serve as an interface between the standard SPI of a microcontroller or microprocessor and a serial I2C-bus. The SPI to I2C-Bus Bridge allows the host to communicate directly with other I2C-bus devices. The SC18IS604 can also operate as an I2C-bus controller-transmitter or controller-receiver. The device can control all the I2C-bus specific sequences, protocol, arbitration, and timing.