Onboard serial interfaces for integrated circuit (IC)-to-IC communications are dominated by the Inter-Integrated Circuit (I²C) and the Serial Peripheral Interface (SPI), which have been available since the 1980s. These interfaces are widely used for connecting lower- speed sensors and ICs to microcontroller units (MCUs) for intra-board communication over short distances. However, as digital systems get faster, these interfaces, limited to typical data rates of 1 megabit per second (Mbit/s) for I²C and 10 Mbits/s for SPI, have become a limiting factor. Other limitations, including dedicated interrupt or chip enable lines, require additional signal connections, increasing the number of wires and complexity of the bus connections.
The Improved Inter-Integrated circuit (I3C) bus is intended to upgrade inter-IC communications. It offers higher data rates, greater flexibility, and a true two-wire interface with in-band interrupts (IBIs) instead of external ones. This article discusses the characteristics of the I3C interface and why it might be a good upgrade from the I²C and SPI serial interfaces. Typical MCU, IC switch, and sensor devices will be used to show its application. Embedded communications buses Embedded serial interconnects like I²C and SPI have been employed for many years for intra-board communications. They are primarily used as communications buses
between sensors and user interface devices and their control processors. The number of sensors in typical systems has grown to ten to twenty in a phone and significantly more in vehicles. At the same time, communication requirements have become more challenging for designers as the demand increases for higher speed, lower power consumption, and fewer conductors. Designers must meet these demands while maintaining processor control via interrupts and enable lines (Figure 1). Current technology implements the sensor and user control device interface using two-wire I²C or four-wire SPI interfaces. Interrupt, enable, and other control lines are separate from the clock and data lines, resulting in more lines per interface.
OhmFigure 1: Embedded communications should support higher speeds, lower power, and a minimum wire count. (Image source: NXP Semiconductors)
we get technical
39
Powered by FlippingBook