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1 vote

Limiting voltage on voltage monitoring pin

An N channel JFET in combination with a zener diode can be used here. To avoid excessive power dissipation and high voltages across the JFET I splitted the voltage and power using two FETs in series. ...
Jens's user avatar
  • 7,327
3 votes

Limiting voltage on voltage monitoring pin

Try a low drop-out voltage linear regulator set to the maximum voltage you want to monitor, 28V. This can be made up with discrete parts, the schematic below shows the idea. This circuit will force [...
Fabio Barone's user avatar
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2 votes

Confusion with the meaning of virtual com port

Programs could communicate directly with USB devices, and that's fine. And many do. But that doesn't help programs that don't know (or don't go to the trouble of figuring out) USB devices. Consider ...
Tim Williams's user avatar
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0 votes

Confusion with the meaning of virtual com port

On connect, a USB device communicates its device class, and vendor id and product id, and also a string that gives textual information on what it is. The operating system uses all that information to ...
Janka's user avatar
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3 votes

Confusion with the meaning of virtual com port

All USB devices have one or more classes. The simplest USB devices have one Class. Things like mice and keyboards are of the USB HID class (Human interface device). These generally have low bandwidth ...
Chintalagiri Shashank's user avatar
0 votes

Confusion with the meaning of virtual com port

The USB protocol has a number of device classes that represent standard things that could be inserted into a computer and allows them to be communicated with using a generic driver rather than forcing ...
user1850479's user avatar
  • 17.6k
2 votes

USB cables being affected by manufacturing equipment

The problem isn't disturbance affecting USB, but the disturbance affecting the keyboard which detects the disturbance accidentally as valid key presses and then tve key presses are prefectly sent ...
Justme's user avatar
  • 159k
5 votes

USB A mechanical orientation?

Other answers have quoted the specification. The problem is, it defines the preferred orientation of the plug and the designer needs to figure out the corresponding orientation of the socket. This ...
telcoM's user avatar
  • 159
2 votes

USB data does not work on my PCB

Any hints what did I do wrong or how to debug the issue? First of all, you need to check voltages on D+ and D- lines after the board gets power, and make sure that D+ is D+, and D- is D- for PC host ...
Ale..chenski's user avatar
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3 votes

USB A mechanical orientation?

Universal Serial Bus Specification, Rev. 2.0 indirectly answers this question in chapter '6.5.1 USB Icon Location': The USB Icon is embossed, in a recessed area, on the topside of the USB plug. This ...
Velvet's user avatar
  • 4,501
20 votes

USB A mechanical orientation?

Yes. The receptacle tab goes on the top. According to the USB specification, section 6.5.1 there are guidelines on orientation for USB-A receptacles: 6.5.1 USB Icon Location The USB Icon is embossed, ...
MrGerber's user avatar
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1 vote
Accepted

Replace this USB power board

It seems to be an "old" charger USB - BAT with micro-USB like this one Now, it is a USB-C one like this one
Antonio51's user avatar
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1 vote

USB Data communication issue on a panelized pcba hardware test platform

You should put a USB Hub chip on the test assembly. That will do a fine job of isolating all the DUT USB lines from each other. It is actually easier to implement than dealing with muxes you'd have to ...
Kuba hasn't forgotten Monica's user avatar
3 votes

5V on DP and DM pins on FT232RL?

Short answer: No, you should not Longer answer: Sure you can do that. It might destroy your chip but that doesn't technically mean that you can't do it. It's even written right there: So: Don't do it....
kruemi's user avatar
  • 3,539
9 votes

USB Data communication issue on a panelized pcba hardware test platform

It likely is not due to impedance mismatch. A more likely explanation is that either your boards or the chip where the USB lines go to have input protection, which clamps the voltages on D+/D- wires ...
Justme's user avatar
  • 159k
2 votes

12V through USB Type C without PD

I'm sure you could connect an off-the-shelf 12V power supply to the GND and VBUS pins on a USB C socket if you really wanted to, and it would power a 12V device. Just make sure you never connect ...
Simon B's user avatar
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3 votes

12V through USB Type C without PD

No, if you use the CC resistors it defines current at 5V, if you want anything but 5V (up to 15W), you need a USB PD controller. http://kevinzhengwork.blogspot.com/2014/09/usb-type-c-configuration-...
Voltage Spike's user avatar
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2 votes
Accepted

Do FT232 come pre-programmed out of the package?

From the FT232RN datasheet: Section 4.1 Key Features contains: The CBUS lines can be configured with any one of these output options by setting bits in the internal EEPROM. The device is supplied ...
Chester Gillon's user avatar
2 votes

Do FT232 come pre-programmed out of the package?

FT232 are ready to use chips. As they are factory pre-programed microcontrollers, you don't need to ever program them yourself in any way. And your computer needs a driver for any chip before it can ...
Justme's user avatar
  • 159k
0 votes

How is CRC5 calculated in detail for a USB token?

I converted the perl script to C in this pdf file https://www.usb.org/sites/default/files/crcdes.pdf with https://codingfleet.com/code-converter/perl/c/ It is programmed very inconvenient (lol) but ...
hugo289's user avatar
  • 23
4 votes
Accepted

How is CRC5 calculated in detail for a USB token?

Reference The USB organisation has a PDF on how to calculate this. This includes a not-very-obvious reference Perl script for calculating the crc5. https://www.usb.org/sites/default/files/crcdes.pdf ...
jonathanjo's user avatar
0 votes

How is CRC5 calculated in detail for a USB token?

While not a direct answer to your CRC-5 question, keep in mind that besides the polynomial used, both sender and receiver have to agree on: The initial value for the CRC register Should the CRC be ...
SteveSh's user avatar
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1 vote

How is CRC5 calculated in detail for a USB token?

Well, at least I confirmed the first case with pen and paper. The ADDR field is a 7-bit number 1 = 0000001b The ENDP field is a 4-bit number 2 = 0010b The fields are sent LSB first so the bit string ...
Justme's user avatar
  • 159k
1 vote

FT230X using USB-C receptacle not working for data transfer

Since you are making a self powered device, you need to wire it up in a self powered way. You need to configure one of the configurable pins into the VBUS_SENSE mode and the power descriptor should be ...
Ferrybig's user avatar
  • 1,194
1 vote

Home made USB 2.0 device switcher (for mouse/keyboard only)

I am not really keen on spending over $300 KVM switch just to switch between two computers if I can do it for cheaper. What does a KVM switch have that my homemade USB switch doesn't have....besides ...
MacGuffin's user avatar
  • 1,043
4 votes

Home made USB 2.0 device switcher (for mouse/keyboard only)

The mechanical switch does one thing wrong which may kill your USB port. One important point about USB is hot-plugging, and for hardware support, the USB connector is mechanically designed to allow it ...
Justme's user avatar
  • 159k
3 votes
Accepted

A simple visual indicator (LED light?) when a USB fan is on

You can add a resistor and LED in parallel with the fan. simulate this circuit – Schematic created using CircuitLab
Aaron's user avatar
  • 8,061
1 vote
Accepted

How to convert MEMS digital microphone to USB?

Updates: The so called "voice-to-bits" solution is apparently just a marketing term. The output of the microphone is just PDM. After applying a low pass filter, I get the analog audio ...
Deling Ren's user avatar

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