The Technology Vent and Rant Thread

[DNSB]

Originally Posted by Renate

The good UARTs use an FTDI232R chip which can use an external voltage for the logic level shifters.
There is the 5V already on USB Vbus, the chip has an internal 3.3V regulator and PCB manufacturers add a 1.8V, 2.5V and sometimes a redundant 3.3V regulator.

The problem was the screened print that said showed J1 5V, J2 3.3V, J3 2.5V, J2 & J3 1.8V (I don't have the board in front of me so I think that was the pattern). Unfortunately, J1-J3 were reversed. He was lucky in that his original project used 3.3V so J2 was correct. His next project was supposed to use 1.8V so J2 & J3. Luckily J1 & J2 was invalid and set the output to < 1.0 V so no damage was done but no communication could happen. It took a while to figure out just what was going.

[DiapDealer]

I hate it when people confuse doing something online with doing something "virtually." Forms filled out online are not being filled out virtually (and they're certainly not being "filled out online virtually"). They are actually being filled out. Online.

"You can DO it online" suffices.

[ratinox]

Originally Posted by DiapDealer

I hate it when people confuse doing something online with doing something "virtually." Forms filled out online are not being filled out virtually (and they're certainly not being "filled out online virtually"). They are actually being filled out. Online.

Literally.

[JSWolf]

I bought a QI2 15 watt charger for my iPhone. It works. But, the problem with it is I need to use either the included USB-C cable or the included wall wart. If I use my 100 watt charger with a cable capable of high-power, my charger won't work. The included wall wart is 20 watt. I don't know what the cable is capable of outputting. I should test it. I have a gizmo that shows me the power from USB-C or USB-A. It's also very good for letting me know when something is done charging.

[Renate]

Originally Posted by Quoth

Do you mean DVI?

Err, yup.

DGI is Data Gateway Interface, a second interface on the Atmel ICE (CMSIS-DAP standard ARM debugging interface). You can use it as a simple "printf" output.

Of my hub with the five pairs, two of them are used in DP alt mode as outputs that go to a converter for HDMI.
Two of them go as transmit and receive for USB 3 to an internal 4 port hub.
One of those ports feeds an ethernet interface, the other three go to jacks.
The remaining lower speed pair is for USB 2 and feeds the USB 2 part of the 4 port hub.

[Quoth]

Originally Posted by DNSB

The problem was the screened print that said showed J1 5V, J2 3.3V, J3 2.5V, J2 & J3 1.8V (I don't have the board in front of me so I think that was the pattern). Unfortunately, J1-J3 were reversed. He was lucky in that his original project used 3.3V so J2 was correct. His next project was supposed to use 1.8V so J2 & J3. Luckily J1 & J2 was invalid and set the output to < 1.0 V so no damage was done but no communication could happen. It took a while to figure out just what was going.

It's annoying when stuff like that is wrong.

Also what did a certain European supermarket chain think they were doing with a red flash at the negative end and black band at the positive end of the battery. Why does the USA use white for neutral and black for mains on the live?


As non-rant aside:
LS-TTL (and maybe HCT) is compatible with 3.3V logic, as long as the supply is 5V, because logic "1" is about 2.7V. This is why 4000 series and 74HC series isn't compatible with original or LS TTL, and why there is an HCT series.

Indeed some UARTs work at 3.3V or 5V logic. The TTL serial port on Victron gear works at 3.3V or 5V, though the optional supply out (needed for a simple isolated serial interface) is 5V only.

I've used 74LS TTL to interface to a 3.3V JTAG connector.

[ratinox]

Originally Posted by JSWolf

I bought a QI2 15 watt charger for my iPhone. It works. But, the problem with it is I need to use either the included USB-C cable or the included wall wart. If I use my 100 watt charger with a cable capable of high-power, my charger won't work.

Sounds like you have a defective charger or it's off spec for USB PD.

[JSWolf]

Originally Posted by ratinox

Sounds like you have a defective charger or it's off spec for USB PD.

It's not the only USB-C device I've seen that has this issue. It's more common then you think.

[ratinox]

Originally Posted by JSWolf

It's not the only USB-C device I've seen that has this issue. It's more common then you think.

I know it's common but it's not a problem with USB-C. It's a problem with manufacturers implementing non-standard power requirements. My go-to example is Nintendo Switch's off spec 5/15V at 2.6A (39W) causing overheating, melting and possible ignition of chargers and docks supplying on spec 20V at 1.95A (39W). Just because it's common does not mean these devices are not off spec. They ARE off spec, and the only things you can do are replace with on spec kit or using the matching off spec power supplies.

[Quoth]

I've found that if a charger is supplied for USB, that's the one that has to be used, unless the charger has an exact spec and that matches. The USB-C gadgets have all the options that used to be on USB (as some are simply a USB-C socket on micro-USB circuit), plus there are at least 3 different schemes for more than 5V.

It's a mess.

Devices used to have on them at least the current when all were 5V*. Recent USB-C devices I've got don't list the standard used, or current or voltage, anywhere.

[* Though it might have only taken 500mA if the device and charger didn't have the same spec. Apple was different on USB-A end.]

[ratinox]

Originally Posted by Quoth

I've found that if a charger is supplied for USB, that's the one that has to be used, unless the charger has an exact spec and that matches. The USB-C gadgets have all the options that used to be on USB (as some are simply a USB-C socket on micro-USB circuit), plus there are at least 3 different schemes for more than 5V.

USB Power Delivery (USB PD) makes this mess go away, assuming device manufacturers comply with the specs. I have one 140W USB PD single device power supply and one 75W USB PD three device power supply for travel. All of my USB PD devices work with both except for my notebook which requires 100W. The 75W wart can't provide sufficient power for it. I also have a 100W USB PD power bank which will power up to four devices simultaneously up to 100W total.

[Quoth]

Originally Posted by ratinox

USB Power Delivery (USB PD) makes this mess go away, assuming device manufacturers comply with the specs.

But there are multiple specs. No-one is enforcing use of just one spec. Also the millions of devices out there.

Someone will add a new spec and there will also be USB PD 2.x

So no-one can make the mess go away.

Also USB-C isn't a single standard for non-power.

The existing devices also need to be supported, and not everything still on sale is USB-C

There is the separate issue of data speeds (USB 1.x to 3.x)
Signals (there are micro and mini that don't just do USB serial data, but analogue audio, stereo + composite video etc). USB C can be USB 1.x, 2.x or 3.x data, analogue audio, DP style digital video or ethernet, but only one at a time. Power signalling can be by extra dedicate power serial interface, or using the regular USB D- & D+ (which can be by serial data to charger, or sensing charger resistances or voltages).

The USB-A is usually a host, but sometimes on USB 3.0 there is A to A!
The USB-A has 4 connections or 9 if USB 3.x speeds are supported.

There are USB 3.x versions of micro-USB and USB-B sockets that allow original plugs or bigger USB 3.x plugs

Even Mini-USB as well as Micro-USB can have the USB-C reverse mode where the gadget client becomes a host and can supply power instead of charging the gadget. Some Micro-USB and some USB-C gadgets can become a host for data and still be a client for charging.

There are at least 5 kinds of client connector with Host USB-A < 3.x (1 pair + power), including USB-C with 4 wires.

At least four kinds of client connector with Host USB-A 3.x (9 wires): USB-B, micro-USB (both larger sockets compatible with older plugs), USB-C and crazy USB-A USB 3.x.

If you are lucky a USB-A socket has SS printed at it if USB-3.x, but you should be able to see the 5 extra connections in front of the original 4.

If you are lucky a USB-C socket might have DP printed on it, if the alternate digital video mode is supported, but your cable might not work.

The different alternate data modes of USB-C are mutually exclusive. It's stupid. The equipment should simply have an HDMI socket, or a mini one, not Alt DP. It should have a 3.5 mm jack for audio, not the Alt Analogue on USB C. A laptop or big tablet should have a dedicated power socket at 5, 12 or 20V. Easily could be three sizes. There should be an ethernet socket on laptops.

The idea of USB-C doing everything is stupid, then an insult to put only one socket even though is used for charging, data I/O, and video (and often can only do one of those at a time).

It's a mess and now nothing can fix it.
https://m.xkcd.com/927/

USB started being broken at the start because it was "only" for slow peripherals such as keyboard, mouse and joystick, but idiots used it instead of SCSI for scanners (too expensive and big), or instead of Firewire (too much royalty).
USB 3.0 needed more wires. The backward compatible USB-A, micro-USB and USB-B connectors made that a mess. Should not have been USB at all.

USB-C is the ultimate mess, trying to replace all the connectors, inc 3.5mm jack, USB-A, Ethernet RJ45 and DP/HDMI and dedicated power connections with one cable and one connector. Good luck on getting a cable that does USB 3.x, or 2A, or Display end to end.

It's a mess.

[Quoth]

Originally Posted by ratinox

I also have a 100W USB PD power bank which will power up to four devices simultaneously up to 100W total.

Four compatible devices if you want max charge/power. Also it need 4 totally independent supplies because there could be 4 different voltages needed.

So you need 2 or 3 chargers when you travel?

[ratinox]

[cut because not a rant]

[PeterT]

[RANT]Sigh. While this is fascinating it's not a rant.

PLEASE could we stop polluting the rant threads with discussions on the rants.

Either start a new thread per rant or do like P & R does and have a catch all Rant discussion thread.

[/RANT]