STMicro has finally launched their first MCU series boasting I3C peripheral support with an impressive 1023 CoreMark making it currently the world’s fastest Arm Cortex-M33. The introduction of the new STM32H5 series is an important milestone for industry adoption of I3C, as the STM32 family of devices is an industry stalwart. It would not be possible to consider I3C as a 'mainstream' protocol if it continued to remain absent from the STM32 MCUs. I'll share more thoughts on this below their marketing teaser video.
Now, before I dig into the specifics of the I3C implementation, there's a few other bells and whistles that deserve mentioning. Most notably, the STM32H5 is also the first MCU in the series to come with SoC security services through an industry-standard API. The STM32Trust TEE Secure Manager saves developers time by providing easy to access security features without needing to write their own code or being security experts.
In true ST fashion, this family of MCUs includes a full menu of memory and packaging sizes, as shown in the table below, and the best part is that some of these are already available now!
STMicro says that mass production has already started and the full lineup and package choices will be introduced in June 2023.
With that out of the way, let's talk about ST's I3C protocol support in this device. The I3C peripheral itself is capable of 12.5MHz SDR transactions (no HDR-DDR mode support), and implements v1.1 of the MIPI I3C specification. A real highlight of this I3C hardware implementation is that it has its own dedicated VDDIO supply pin which allows the I3C bus (along with other protocol peripherlas) to operate down to 1.2V. Other vendors have been working on similar implementations to support I3C at lower voltages, but this one going all the way down to 1.2V is best-in-class.
Another thing that STMicro brings to the table is fantastic support and documentation, and that holds true for their I3C functionality as well. There are currently two I3C-related application notes available:
1. Introduction to I3C for STM32H5 series MCU (AN5879) - This app note is the perfect place to get started learning about STMicro's I3C peripheral. A blend of explaining the protocol along with their implementation, the document is realtively easy to digest. At 64 pages long, it starts at the highest level, but also gets into the nuanced details as you read on. There's a helpful table showing which features are supported in Controller mode and Target mode. The second half of the document presents the example projects (9 of them currently) that are available and shows how to get up and running with them.
2. I3C Protocol used in the STM32 Bootloader (AN5927) - This app note explains how you can use I3C protocol to perform a firmware update using STMicro's embedded bootloader. This just goes to show you how much STMicro is invested in I3C support that they've updated their bootloader to support I3C as a firmware update interface. It's also interesting to see this because it alludes to the usefulness of the MIPI Debug for I3C protocol, which aims to provide a vendor-agnostic implementation for these types of activities over I3C. I'm eager to see where this leads.
If you’re itching to get your development on you should check out the ST development kits including the NUCLEO-H503RB, NUCLEO-H563ZI, and STM32H573I-DK which range in price from $15 to $99. For those lucky enough to drop in at STMicro's booth at Embedded World this year, they were handing out these dev boards for free to celebrate the launch of this device. We're eager to find time to experiment with it here in the office.
Annecdotedly, we've heard from a few customers that getting up and running with the I3C examples on this board is relatively quick and simple compared to doing the equivalent with the NXP's I3C App notes for iMXRT685 and LPC5536 eval boards.
Already working with I3C? Check out our I3C Basic Protocol Analyzer Plugin for Saleae Logic...
