I2C, I2C-bus, Standard-mode, Fast-mode, Fast-mode Plus, Fm+, High Speed, Hs, inter-IC, SDA, SCL Philips Semiconductors (now NXP Semiconductors) developed a simple bidirectional 2-wire bus for efficient inter-IC control. This bus is called the Inter-IC or I 2C-bus. Only two bus lines are required: a serial data line (SDA) and a serial clock line (SCL). Serial, 8-bit oriented, bidirectional data transfers can be made at up to 100 kbit/s in the Standard-mode, up to 400 kbit/s in the Fast-mode, up to 1 Mbit/s in the Fast-mode Plus (Fm+), or up to 3.4 Mbit/s in the High-speed mode.