Tagged Questions

USB is Universal Serial Bus. If your question relates to a specific chip, please mention it in your question.

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0
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1answer
21 views

Connect / disconnect USB while external power source remains connected

I have some arduino mini pro collecting environment data, so they operate a long time collecting and I need to connect Gnd - Rx - Tx once in a while to transfer data to my PC, and then disconnect. I ...
0
votes
0answers
21 views

Atmega 168A fuse programming

I'm currently programming over an Atmega 168A micro controller through a USB Tiny programmer and an ISP interface. The micro controller is set up with an external oscillator and an external person ...
1
vote
1answer
29 views

Series Damping Resistor for Low-Speed USB

The USB 1.1 spec gives well-defined \$V/I\$ characteristics for full-speed output drivers, which can be used to find the series damping resistance, \$R_S\$. The low-speed output schematics also ...
2
votes
2answers
64 views

Is there a USB alternative to Mass Storage which works at the filesystem layer?

Is there a USB alternative to Mass Storage which works at the filesystem layer? The goal is to be make a USB device which is mountable as a filesystem, not a block device. The difference is that ...
1
vote
2answers
68 views

How to make a simple USB gadget without vendor and product ids'

I would like to control a simple servo or led with USB. I opened the cable up and connecting the red and black wires to the servo made it spin properly with about 5V, as those are VCC and GND. Ok. ...
0
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0answers
4 views

How to connect Arduino Pro Mini with PC? [migrated]

I'm about to buy Arduino Pro Mini (http://arduino.cc/en/Main/ArduinoBoardProMini). As far as I can see it requires FTDI or similar circuit to program it. Should FTDI be present for communication with ...
0
votes
2answers
59 views

How does USB superspeed electrical signaling work?

I've been reading a bunch, including the USB 3.0 spec, and I still don't get it. The transmit data lines are both capacitively coupled, so at the connector, SSTX are 0 V average? Yet the voltage ...
1
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0answers
23 views

Placement of ESD protection device on Motherboard and mating daughter PCB for PCB lines in plastic enclosure

I have a motherboard with a USB Hub IC. The USB lines are routed from the motherboard via a connector to a daughter board. This daughter board has the USB connector. The cards are inside a plastic ...
0
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0answers
27 views

stm32f0 USB keyboard LED controlling with DataOut or RxReady0 with endpoint 0

I am making a USB keyboard using stm32F0RBT6 micro-controller. I want to receive data from PC for Caps Lock and Scroll Lock leds. Do I need to initiate a callback funtion like those ones? ...
1
vote
0answers
48 views

Making a program that sends data to USB port [migrated]

I want to create a program that is able to communicate to the USB port on my laptop. From this program I want to send data to the USB port constantly. Basically something like a hyperterminal, but ...
0
votes
0answers
45 views

Protect the USB supply

How can i protect the USB power line from external power line connections? what's happening when i connect 5V line from external power supply (such switching reg) together with 5V USB power line? I ...
0
votes
1answer
34 views

Un-shielded USB 2.0 Signal Connector

I am working on a project that requires that I transmit USB 2.0 over 0.1' headers due to an old design of a test board that used to use low speed USB. The 0.1' headers are an unshielded and I worry ...
0
votes
1answer
68 views

Can I use an electrolytic capacitor on UCAP?

I have a small board based on the ATmega32u4, which I'm assembling. I only have electrolytic capacitors in 1uF value sitting around. Can I use an electrolytic cap from UVCC to ground, instead of a ...
4
votes
1answer
566 views

What's this component?

What is this component?(U6) Source
1
vote
1answer
65 views

Why are there so many USB connector types?

Why are there so many different USB connector types? Is it just that they've gotten smaller as Moore's Law progressed and there was a need for smaller connectors, or is there something more?
-1
votes
1answer
59 views

We're making a bike-powered USB charger and we have (almost) no idea what we're doing

So my friend and I are going to build a USB charger powered by a dynamo. Here is a diagram of what we are planning to do. I have a few questions: 1.) How do we test if the dynamo and breadboard ...
5
votes
1answer
84 views

Placing Via's on PCB

I'm designing a PCB for USB 3.0, the specifications for Differential impedance comes at 90 ohms with a tolerance of +- 5 ohms. I've used different calculation tools but when I have to hold these ...
1
vote
2answers
58 views

USB not detected

I am designing an Atmega32U4 based board. The chip has a USB peripheral and I have made provision for that. But, the board is not detected in the device manager. I am attaching an image of the USB ...
0
votes
1answer
48 views

How to connect an 8 module relay with DAQ NI USB 6800?

I have been trying to figure out how to connect a 8 module relay to a DAQ NI USB 6800 device instead of an Arduino or a Raspberry Pi. Could somebody help me figure out the connections?
0
votes
0answers
53 views

Can a USB 5v 0.5A powered pcb sent data to a 3,5 mm jack using a 2nd usb port via usb-to-3,5mm converter wire?

I am designing a MCU for a device that is powered by USB. This device needs to send simple serial commands to an 3.5mm stereo port on a monitor. The wanted to use USB-to-3.5mm jack converter wire, ...
6
votes
2answers
121 views

Is USB-C a technically viable substitute for SATA Express connectors?

SATA Express, the successor to SATA, is too new to be widely used yet, but the advancing speed of SSDs appears to make it inevitable, the same as SATA replaced parallel IDE. Despite the name, it isn't ...
1
vote
1answer
60 views

Does the USB-C Alt Mode specification require support of the USB 3 protocol?

If a device is designed with a USB-C port that's intended for use exclusively in an alt mode such as Displayport or PCIe rather than for use as a general-purpose USB port, then the hardware to support ...
0
votes
1answer
126 views

Can I split a USB cable's male end, add a second male plug, and draw 10V from 2 ports instead of 5V from one port for a single device?

Say I have a device that accepts 10V @ 2A, and I have a wall-wart with two USB plugs that both output 5V @ 2A. Can I add a second male connector, connect both connectors to the wall-wart's two ports, ...
1
vote
2answers
85 views

Switching between USB power and single alkaline battery

I've read the numerous other questions addressing this topic, but I'm not sure if any of them apply to my situation. I am designing a device that will run off a 3.0-3.3V supply voltage and draw no ...
0
votes
0answers
25 views

Advice: how to integrate minipci cards to a board design

I'm designing a pcb card for one embedded device based on a Digi iMX28 module. In the design we included a couple of minipcie sockets to add 3G and wifi cards. However, there are two flavors of ...
0
votes
0answers
10 views

Dont know where to connect HD AUDIO or AC-97, & USB [migrated]

I'll provide pictures so you guys can see, but basically I recently bought a new case for my pre built lenovo k330b. I cant find how I'm supposed to position the connectors. Please help me out with ...
1
vote
1answer
47 views

USB - Tolerable voltage drop

For a system I am designing I need go over 500mA limit for a very short time (30mSec). I have designed my system such that during the over 500mA period I am able to sustain my circuits using internal ...
0
votes
1answer
64 views

How can I use a greater USB charge current without device enumeration?

I'm designing a device with USB communications, using an STM32F105 microcontroller. It has a LiPo battery, which charges from the USB port using an LTC4077 charge controller. It will generally use a ...
2
votes
2answers
180 views

Why does Ethernet on UTP have much greater range than other modern protocols?

OCuLink, SATA, USB 3, and Displayport all provide on the order of a few Gbps per signaling pair, and are limited to a cable length of just a couple meters. Ethernet via comparable cabling provides ...
-1
votes
0answers
36 views

Need 2.1 Amps from a USB wire for my lighthing conector [duplicate]

I have been working into an ipad Conector, that seems to work FINE its plugged to a 5v 12A switching power supply, this goes to my PCB where it has up to 4 outputs, each output for 1 ipad Air, up to ...
0
votes
2answers
62 views

Can I run a program, on an ATtiny85 with micronucleus bootloader, without usb connected?

I have managed to put micronucleus bootloader on an ATtiny85. Using it, I can successfully upload programs to my ATtiny through USB and they run as they should, as long as they are connected to USB. ...
0
votes
1answer
54 views

Shielding not connected to USB connector causes tablet restarts

I have a custom USB cable, USB type A male on one end and a DB-9 connector on the other end (only using 4 pins). The shielding of the cable is connected to the USB connector but not the DB-9 ...
2
votes
2answers
154 views

2.5mm Jack to USB data Cable

I was recently diagnosed with Type 1 diabetes. With the need to test my own blood upwards of 8 times a day I have a ton of data to keep track of. My testing unit has the ability to upload its data to ...
1
vote
1answer
76 views

USB current limiter and under/overvoltage protection

I know recent motherboards already provide these, but lately USB ports are also available in many different gizmos (smartphone chargers, TVs, standalone players, etc.), which I am often tempted to use ...
0
votes
1answer
59 views

lm2596 fixed 5 volts(usb) from 12v 10W solar panel

I have got a 10 Watt solar panel & a 10000 mha Battery bank. I plan to use the panel to charge the battery bank. I have a LM2596(variable configuration with pot), I plan to use it to charge my ...
0
votes
0answers
52 views

Noise on audio circuit when powered by USB

I built a simple microphone boost circuit which works well with a 3V coin cell however when I switch to USB to power it (battery removed, of course), there's a bit of noise in the 200Hz to 10KHz ...
0
votes
1answer
29 views

Can I use an Adafruit Trinket as a simple Android peripheral?

I want to control the standby state of an LCD panel through an android media PC. I'm thinking of using a Trinket as a cheap android USB peripheral. Is this possible? Or should I be looking at an FTDI ...
3
votes
0answers
69 views

USB termination on STM32F437xx

I'm about to layout the USB connection on our boards and wondering whether the termination resistors and pull-up on D+ are necessary when using the STM32F437xx. The datasheet tells: ...
0
votes
1answer
70 views

My take on an automatic source selector between USB and wall supply

This is my take on an automatic source selector between USB and a 12Vdc wall supply. There is something similiar in this post. The problem I have is the Voltage drop across the diode on the USB 5V. ...
0
votes
0answers
31 views

USB analyzer with trigger generation

We're trying to track down a really nasty problem. We have a microcontroller with an embedded USB device controller engine. Every once in a while, the device NAKs an incoming endpoint 0 Set_Report ...
0
votes
1answer
82 views

How to get USART and USB-Serial working on the STM32F4Discovery Board?

I'm programming a STM32F407VG chip on the STM32F4Discovery board using CooCox CoIDE. I've stitched together a program based on some examples and tutorials I found online to get USART1 through pins ...
0
votes
0answers
29 views

AC to DC converter for 5V USB Charger [duplicate]

I have been looking around to understand how phone chargers can pump out 1-2 Amps of current through the USB port in such a small package. I am sure they do use a transformer for isolation. One of ...
0
votes
0answers
53 views

Custom USB 7 port hub PCB dasiy-chain

I had a schematic laid out for a custom USB 2.0 7-port hub I needed to create for a project of mine. It currently uses Ethernet RJ45 sockets to provide power and data to each hub (2 Ethernet ports for ...
3
votes
1answer
147 views

Floating supply and USB ground

I have a somewhat complex circuit controlled by an Arduino, which is supplied by a self powered USB hub (earth grounded 5V supply). A part of the circuit has to be powered by 12-20V DC. When I plug ...
0
votes
2answers
69 views

FTDI cables confusion

I went to the store and asked for a FTDI cable however, I need a bit of assistance, apparently I didn't properly do my homework before shopping and I ended up with upper pic. I need an FTDI cable to ...
2
votes
1answer
97 views

STM32 USB: detecting connection and disconnection

Using STM32F4 USB Mass Storage Controller example in Device Mode, how do you detect connections and disconnections with a host controller? I tried polling the VBUS pin state yet it could be high from ...
1
vote
0answers
53 views

SPDIF digital audio to I2S to USB controller

I'm looking to take a digital S/PDIF audio signal, decode it as necessary, and send it to a USB controller chip configured as a USB Audio Class device so I have plug-and-play with standard OS-provided ...
0
votes
0answers
21 views

Piranha LED board connected to USB charger [duplicate]

Can I use this Piranha Light board to connect to a 5v power source like a USB charger? Do I need something extra (more than an USB-cable)? And can I connect more boards to the same circuit? (New to ...
12
votes
6answers
2k views

Is it possible to step-up the output of a laptop USB port to 12 watts?

I've got a USB device that requires 12 watts to charge. My laptop appears to output less that that. My question is: Is it possible to step-up the output of a laptop USB port to 12 watts?
0
votes
1answer
56 views

Drain Li-Ion battery by connecting USB +5V and GND

I have a sportswatch which can be connected to a PC via USB for downloading the training information, upgrading the firmware, etc. I have used those features for a year on weekly basis, but since ...