New Real-time Oscilloscope Tackles the Debugging Challenges of I3C

June 14, 2022 by Jake Hertz

A new oscilloscope may ease the pain points of designing and debugging devices using the I3C communication protocol.

As technology continually advances to faster speeds and lower power, designers expect highly accurate test and measurement techniques. Faster hardware speeds require improved lab tools like oscilloscopes and logic analyzers to precisely test and debug circuits.

One new technology that is challenging existing testing technologies is I3C, a faster, more robust version of I2C. To address this protocol, Introspect Technology released a new embedded real-time oscilloscope designed with I3C-based hardware triggers.


PurVue Analyzer example

Typical application of the I3C PurVue Analyzer identifying subtle single-shot signal artefacts. Image courtesy of Introspect Technology

In this article, we’ll discuss the I3C protocol, considerations for test and measurement of I3C devices, and the unique features of Introspect's new oscilloscope.


What is I3C?

Improved Inter-Integrated Circuit (I3C) is a communication protocol released by the MIPI Alliance in 2016 as a way to improve existing I2C communications.

Similar to I2C, I3C is a protocol for synchronized data transfer between master and slave devices that share two total lines: serial data (SDA) and shared clock (SCL). One significant change from I2C to I3C, however, is the change from an open-drain output to a push-pull output.


I3C bus diagram

I3C bus diagram. Image courtesy of Prodigy Techno

As a result of this change, I3C offers significant improvements in terms of data rate and power consumption because it no longer requires pull-up resistors on the SDA line. Hence, I3C is an improvement from I2C by providing faster transfer speeds, lower power consumption, and fewer external components. I3C offers a standard data rate of 12.5 MHz and a maximum of 100 Mbps while I2C maxes out at roughly 5 MHz. 


Debugging I3C

When it comes to testing and measurement with the I3C protocol, there are a number of unique challenges.

One of the major use cases for the I3C protocol is for buses that consist of multiple mid-speed sensors and control circuitry. Many of these sensors tend to require always-on monitoring to notify the master of a change in state or initiate data transfer. To address this requirement, MIPI added a key feature to the I3C protocol: the ability for in-band interrupts, where slave devices are able to take control of the data bus and initiate interrupts.


I3C can use both SDA and SCL lines

Like I2C, I3C can use both SDA and SCL lines. It also supports legacy I2C devices and I3C slaves and masters. Image courtesy of Tektronix

This becomes a challenge for testing and measurement, however, since lab equipment needs to go beyond the standard functionality of an oscilloscope to offer special triggering functions for these bus interrupts. Simply put, I3C requires lab equipment that can act both as a protocol analyzer and a real-time oscilloscope, allowing for thorough, end-to-end insight into the protocol’s behavior. 


New Embedded Real-time Oscilloscope for I3C

To address the challenges of testing with I3C, Introspect Technology released a new embedded real-time oscilloscope with I3C protocol-based hardware triggers. 

The new product, called the I3C PurVue Analyzer, is a high-speed oscilloscope meant for real-time data collection with the built-in functionality of I3C-specific protocol triggers. The product takes the protocol analyzer from Introspect’s SV4E-I3C I3C Test and Debug Module and merges that functionality with a high-resolution real-time oscilloscope that simultaneously samples the protocol analyzer inputs.


The I3C PurVue Analyzer

The I3C PurVue Analyzer. Image courtesy of Introspect Technology

The system keeps the protocol analyzer state machine constantly running in the background and triggers the internal oscilloscope based on protocol events. In this way, trigger events are guaranteed to be found, regardless of irregularity. By combining these two functions, the new product can trigger the oscilloscope to capture analog waveforms and provide exact time-correlated analog and digital measurements. 

From a performance point of view, the I3C PurVue Analyzer offers 500 MHz of bandwidth, a 1 Gsps sampling rate, and 12-bit resolution on two simultaneous channels. The system as a whole offers up to 1 Gbyte of memory and features standard USB 3.0 interfaces for data retrieval.

According to Introspect Technology, the new analyzer fills a large gap in the current testing and measurement technology market and hopes to provide engineers with the ability to more reliably interpret and debug signal integrity issues.