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SILICON SILIC CHIP www.siliconchip.com.au Publisher/Editor Nicholas Vinen Technical Editor John Clarke – B.E.(Elec.) Technical Staff Jim Rowe – B.A., B.Sc. Bao Smith – B.Sc. Tim Blythman – B.E., B.Sc. Advertising Enquiries (02) 9939 3295 adverts<at>siliconchip.com.au Regular Contributors Allan Linton-Smith Dave Thompson David Maddison – B.App.Sc. (Hons 1), PhD, Grad.Dip.Entr.Innov. Geoff Graham Associate Professor Graham Parslow Dr Hugo Holden – B.H.B, MB.ChB., FRANZCO Ian Batty – M.Ed. Phil Prosser – B.Sc., B.E.(Elec.) Cartoonist Louis Decrevel loueee.com Founding Editor (retired) Leo Simpson – B.Bus., FAICD Silicon Chip is published 12 times a year by Silicon Chip Publications Pty Ltd. ACN 626 922 870. ABN 20 880 526 923. All material is copyright ©. No part of this publication may be reproduced without the written consent of the publisher. Subscription rates (Australia only) 6 issues (6 months): $65 12 issues (1 year): $120 24 issues (2 years): $230 Online subscription (Worldwide) 6 issues (6 months): $50 12 issues (1 year): $95 24 issues (2 years): $185 For overseas rates, see our website or email silicon<at>siliconchip.com.au I3C: coming soon to an IC near you If you’ve worked with digital chips, especially microcontrollers, you will be familiar with the major serial buses, including I2C and SPI. They are very common ways of controlling external chips and transferring data between them. Many of our projects that use micros include one or both. I2C has the advantage of requiring fewer wires (two plus a ground versus 3-4 for SPI), multiple chips can be on the same I2C bus as they have unique addresses, and chips running off different voltages (eg, 3.3V & 5V) can be on the same bus. However, I2C is quite a bit slower than SPI (typically around 400kbps or 1Mbps compared to, say, 20Mbps), so it’s mainly used for sending commands and small amounts of data. It turns out that a consortium including Intel, ARM, ST Micro, TI, Samsung and Nokia released the specifications for a new bus called I3C in 2017. It has some of the best features of both systems. Oddly, it hasn’t gained widespread adoption yet, and I have only just heard about it. One possible reason is that it is a somewhat ‘closed’ standard, as you have to be a ‘member’ to get the full specification; unlike I2C where it is a free download. I think that is a poor move. If they want people to actually use this and for it to become standard, they should make it fully public. DDR5 computer memory, which is coming into widespread use now, apparently makes use of I3C. I haven’t looked into it in detail; I assume it is the bus used for communications between the onboard memory controller and the computer CPU. I3C is somewhat backwards compatible with I2C and retains pretty much all of its advantages, while increasing the bus speed to the point that it’s almost as fast as SPI. SPI retains an advantage: each pair of devices has a dedicated communications channel, and other devices cannot reduce the bandwidth or interfere with timing of data transfers or commands. But there are many applications where I3C will be good enough, and I think SPI will only be used in specific situations once I3C is more widely used. Some microcontrollers are now available with support for I3C, such as the PIC18-Q20 series, and sensors supporting I3C are ‘coming soon’ from major manufacturers. For more information, see siliconchip.au/link/abgm and https://w.wiki/5fgX Please keep your e-mail address up to date Editorial office: Unit 1 (up ramp), 234 Harbord Rd, Brookvale, NSW 2100. Postal address: PO Box 139, Collaroy Beach, NSW 2097. Phone: (02) 9939 3295. ISSN: 1030-2662 Printing and Distribution: With the cost of postage constantly increasing, it has been very helpful for us to be able to e-mail subscribers when their subscription is about to expire. It’s especially important for people with online-only subscriptions as we might not even have their address for sending a renewal reminder letter. It’s frustrating when those reminders bounce because the subscriber has not told us about a change in their e-mail address. If you change your e-mail address, please update your account to reflect that. If you don’t know how to do that, let us know via phone or e-mail, and we’ll do it for you. You can recover your account if you forget your password to our website, but only if we have your current e-mail address. I advise avoiding using e-mail addresses provided by your internet service provider (ISP) or a work address. Instead, use a service like Gmail, Outlook, Yahoo!, iCloud etc. That way, if you change ISPs or jobs, your e-mail address will remain the same, and you won’t have to update it everywhere. 24-26 Lilian Fowler Pl, Marrickville 2204 by Nicholas Vinen Recommended & maximum price only. 2 Editorial Viewpoint Silicon Chip Australia's electronics magazine siliconchip.com.au