2019-09-04 (Wednesday)

Today, I learned that:

There is finally something really BIG happening in the world of serial communication between electronic devices. Last Thursday, 2019-08-29, was officialized the release of a new version of the popular USB interface, version 4, USB4 to be short, with a maximum data rate of 40 Gbit/s. See also reference #1 below.

From RS-232 to USB4

So, what is so special with this version then? Well, it seems that we now, almost 60 years after the RS-232 serial protocol was introduced, have returned to only one standard, regardless of the brand of the device.

It all started in 1960, when the American industry organisation EIA (Electronic Industries Association) introduced the RS-232 standard, initially to be used between electromechanical teletypewriters as DTEs (data terminal equipment) and modems as DCEs (data circuit-terminating/communication equipment). According to today’s standards, it was extremely slow, maximum 20 kbits/s.

RS-232 had some successors, such as RS-422 and RS-485, where both the speed and maximum cable length had been improved. For example, RS-422 is specified for a maximum bitrate of 10 Mbits/s and a maximum cable length of 1500 m.

We now jump to the 1990s, when the emerging personal computer (PC) industry found that maintaining the RS-232 communication was not feasible. There were then started two different initiatives to make communication between a PC and its peripherals much easier and faster. On January 1, 1996, was released the first version of the universal serial bus (USB). It had been developed by a consortium of companies such as Compaq, DEC, IBM, Intel, Microsoft, NEC, and Nortel. The data rate of USB 1.0 was 12 Mbits/s, which was improved to 480 Mbits/s with version 2.0 in 2001 and 5 Gbits/s through USB 3.0 in 2014, 10 Gbits/s by USB 3.1 in 2014, and 20 Gbits/s specified by USB 3.2 in 2017.

As you can see above, Apple did not participate in the USB consortium. Instead they had decided to develop their own communication interface, and attracted other companies such as Sony, Panasonic, Philips, LG, Toshiba, Hitachi, Canon, Thomson, and Texas Instruments. This group developed what came to be known as FireWire 400, aka standard IEEE 1394-1995. The data rate of this version was a maximum of 400 Mbits/s in half-duplex mode. It was followed by FireWire 800, which reached the speed of its name in 2006. However, Steve Jobs declared that FireWire was dead in 2008 when many camcorders were still using USB 2.0, instead of the faster FireWire.

Intel, which as you saw before already was a leading force in the USB consortium, now started to develop a new hardware interface together with Apple. It was dubbed Thunderbolt, and the first version appeared on MacBook Pro computers in 2011. Sony also used it in a Vaio line of notebooks in 2011. It was later followed by Thunderbolt 2 in 2013, with a maximum data rate of 20 Gbits/s.

And then, in 2016, Thunderbolt 3 was introduced, and as of now we can see that both standards are coming closer to each other, because they share the same USB-C connector. Intel decided in April 2019 to release the Thunderbolt without charging royalties from the companies who would use it, and that was the signal to finally use Thunderbolt 3 as a starting point for the specification of USB 4.

Will this mean that there is now unanimity in the electronics industry to start using only USB 4? Let us hope so, and that we will see the concrete result starting to appear in about a year or so.

There is much more to be said about this interesting topic of data communication, please see references # 2 through 7 below for details.

If you can’t beat them, join them!

A big problem in the crazy traffic in major cities around the world is of course that so many different categories of people on the move need to share the same physical space. Maybe the most troublesome is when motorbikes try to squeeze their way through in the small corridors between the cars. In 1997, when the most recent Brazilian Code for traffic was published, it permitted that they could do so, contrary to safety measures. And as a consequence, every day quite a few of those bikers are involved in severe accidents, even deaths.

If you can’t beat them, join them! In order to reduce the conflict between cars and motorcycles, in the largest avenues in São Paulo have been implemented a buffer zone, exclusive to the bikers, in front of the pedestrian crossing. That way, they can race off without messing with the cars. Photo taken at Avenida Ipiranga on 2019-08-08.

However, one of the ways to mitigate somewhat this conflict was created in 2013 in São Paulo. You can see it in the photo above, taken downtown on 2019-08-09 at Avenida Ipiranga. It shows that motorbikers and other bikers, as well, have a privileged zone in front of the cars, when they need to stop for a red light. That way, when the light turns into green, they can speed away without needing to negotiate space with the car drivers. This method is called “Frente segura”, which means ‘Safe front’. More about it can be seen in reference #8 below (in Portuguese).

That’s what I learned in school !

Refs.:

1: USB4 Specification merges Thunderbolt 3 and USB with transfer speeds up to 40 Gb/s

2: RS-232

3: RS-422

4: RS-485

5: USB

6: IEEE 1394

7: Thunderbolt

8: Frente segura

*: What did you learn in school today ?

2016-01-12 (Tuesday)

Today, I learned that:

The common expression “gigabyte” so often used today when talking about a quantity of data is not always a gigabyte, here is the story:

Some time ago, I discovered that there was a new type of USB flash drive (‘pen drive’) in the market, the handy little memory device that lets one move chunks of data from one computer to another. This particular device would be specially suited for transferring data from desktop/laptop computer to a smartphone, and vice-versa. The reason for this is that the drive has two different ports, one with a regular USB-A male connector and the other with a micro-USB AB receptacle. I decided to buy the smallest one, specified at 16 Gbytes of memory.

When it arrived, before even saving any file onto the drive, I investigated if it really could hold 16 Gbytes as specified. Well, it could not! My Mac computer showed that the maximum capacity when using a file format called Extended File Allocation Table (exFAT), which would permit compatibility between OS X, Windows and Android, was 15 549 300 736 bytes, also informed as 15,55 GB by the Mac. In Windows, it was even less, 14,4 GB. So how come this difference, more than 1 GB?

The reason is that Apple uses the decimal definition of gigabyte, where 1 gigabyte (GB) = 1000 x 1000 x 1000 bytes = 1 000 000 000 bytes, and Microsoft uses the binary definition, that states that 1 gigabyte (or more correctly 1 gibibyte – GiB) = 1024 x 1024 x 1024 = 1 073 741 824 bytes.

The recommended international standard, in unison with the International System of Units (SI), is to use only the prefixes kilo, mega, giga, etc. as multiples of 1000, and kibi, mebi, gibi, etc. as multiples of 1024.

The word gibi is also used in Brazil to denote a comics magazine, in Swedish called ‘serietidning’.

… That’s what I learned in school!

Refs.:

1: USB flash drive

2: USB

3: ExFAT

4: Gigabyte

5: Gibi

+: What did you learn in school today ?