I'd like to control a few input pins (say 5) and a few output pins (at least 2) from a computer. The computer has no parallel port. What is the best way to do this? USB-to-parallel adapter (anybody have one to recommend which works on Linux)? Or perhaps there is some other general purpose USB "control board" where I can use read input from some pins and write output to others? I don't even know what to google for, so any pointers are appreciated!
121240
I'm working on a project which involves having users press buttons on a webpage which the server needs to send onto a microcontroller in the form of a GPIO signal. The only ports available on the server are USB.  I have had a couple of thoughts:   Just use an Arduino board as the USB to GPIO interface. Use a purpose-built module such as the  (this is pretty much the only one turned up in a quick Google search. Use something like what is described in this question.    Can anyone with experience in this area make a recommendation?
111054
I am planning to implement V-USB with an ATMega8 microcontroller. I am interested in implementing an HID device; more specifically, I want to try and make my own simple 26 key keyboard (each corresponding to a letter of the English alphabet).  This may be a stupid question, but do I need an input pin for each key I implement? In other words, will I need to use a microcontroller that has at least 26 I/O pins? Or is there another way to do this?
62725
I have to plugin my USB Audio adapter ( 4300054 Gigawire USB Audio Adapter) for audio input because has a combo-input-output port for voice.  After I do this, I have go open Sound Settings and manually select the USB Audio adapter for Input and Output, if I do not, the system default remains selected.  Is there anyway, I can make Ubuntu to automatically select the USB Audio Adapter as the default as soon as I plug-in?
4105
Following an earlier question ,  I would love to implement the  as suggested by Russell McMahon.   That way I could switch between 4AA batteries (1.2V*4 or 1.5V*4) and USB power. The battery voltage would nicely be regulated to 5V too. And the idea was to use the shutdown pin of the chip IF USB power is detected. The device also has to work when no batteries are present.  I am not too experienced with this, but I thought to connect the 5V from the USB to the SHUTDOWN pin from the LDO chip. Pitywise, the pin function is inverted, if SHUTDOWN is low, Vout from the LDO chip is low.  I am now considering using an XOR gate to make the thing work:         &ndash; Schematic created using   I would love to limit the amount of components, but the number of diodes is already high, and the whole thing feels a bit crafted   My questions:    Is there a better suitable chip (with an inverted shutdown pin) is there a better circuit (without voltage drop) to get this (I would prefer to get rid of D1, but then, the XOR has no desired operation)
22633
Can I charge computers by inducing 5-volt into their USB connectors? Is this possible? I noticed that when my EeePC 900 is off but plugged in charger, there is power coming out of the USB port. Can this be a sustainable way of charging a PC, or a flaw in design?
86877
I am working on an MSP430 project that requires me to route the output of one peripheral into the input of another peripheral. Thus, I have two MCU pins connected directly to each other. This looks suspicious to me since there is the possibility of a programming error causing both to be (possibly conflicting) outputs. Also, there is the issue of startup and programming states.  In the worst case, if one pin is driving HI, the other is driving LO, the GPIO pins generally have way more sink capability than source capability... so it'll be somewhat like taking a HI output and shorting it to near-ground. Which is bad... but how bad is it? Is it likely to cause damage to the MCU?  I often see examples on the web of people using Arduinos to light an LED between two pins without a resistor, and I haven't heard of any stories of anyone frying anything but the LED. Clearly you wouldn't want to do this in a product, but do manufacturers generally try to protect the MCU from GPIO pins being overloaded anyway?  Thinking about it in retrospect, putting a current-limiting resistor between the two pins would have prevented any worries, but even a minor hardware change is a very difficult thing to do at this point.  For future reference and the benefit of posterity, does anyone have any other ideas about the proper way of minimizing the risks of connecting two MCU pins together, and more generally, minimizing the risks that come from the possibility of overloading a GPIO pin?
36299
I'm launching a VM using qemu-system-x86_64. I know two ways to pass through a USB device.  Say for example, I had a mouse that showed up in lsusb like  Bus 003 Device 011: ID 6ade:9582 Amazing Mouse Maker   I could pass it through using  -device usb-host,vendorid=0x6ade,productid=0x9582   or  -device usb-host,hostbus=3,hostaddr=11   Neither of these I really like. If I grab it by Vendor/Product ID then I will never be able to reclaim that mouse until the VM is turned off.  If I grab it by BUS and Device number, then I will have to tell Qemu to reacquire it if I unplug it.  Is it possible for me to send it by Port (the actual physical slot)? Say it's plugged in to Bus 3 Port 2. Can I pass it by that?
64601
I have a (old) computer that I am trying to use, just for giggles. It has a 9-pin (RS-232) output for the monitor (marked 10101). Can I connect it to my VGA monitor using an adapter?  EDIT   Thanks for you input guys. But the serial port has both, the 10101 and rectangular symbols next to it!     What does this mean?
162
How to check the opened/closed ports on my computer?  I used netstat -a on command line.   Does the port status "LISTENING" indicate that the port is open? Is any port, that is not shown in the output, closed?
100162
I just bought a 5 volt dual relay module for my arduino.  But now that I have it I was wondering if there is any way that I could control it directly from USB.    The pinout of the module is GND  ONE  TWO  VOC This would make it really easy to just connect a USB cable to it. Assuming I did that is there any way to send 5 volt through the USB Data+ and Data-?  Thank you
40147
On Linux, I want to send a command string (i.e. some data) to a serial port (containing control characters), and listen to the response (which also usually might contain control characters).   How can I do this as simplest as possible on Linux? An example is appreciated!
41393
I've have this socket on my laptop (Lenovo Z570).  What is this port and what is it used for? And what does that symbol mean (I expected a LOCK symbol)?
91589
I'm looking to allow two cartridges to be inserted into a slot that normally only accepts one (more specifically, Nintendo 64 cartridges). I can't just toggle the power lines to each cartridges because of backfeeding. What sort of device would I need to use to switch a large number of lines from one cartridge to another (an N-pole single throw relay)? In this case, there isn't much power passing through the lines, but in a more general sense what component would one need to actuate multiple switches in a near-simultaneous timeframe?
52935
I'm making a small project which will take +5v from USB, What should I do with the D+ and D-, keep it open or short them to ground or do I have to add some components?  I want to run ATMEGA168 and 16x2 LCD with back light.
96516
Generally, in connecting power supplies parallel one can follow current control or droop control rather than voltage control to regulate the output of a dc dc converter. If the output of both the converters are connected together. As shown in the figure  Then we can implement those current controlling methods mentioned above. What if the converters had different output. The figure shows with different output  What kind of strategy do we use here current or voltage. I am thinking that the converter output terminals are not connected together and there is no need to see how much current flows through each converter and voltage controlled mode will be used. Is this correct or wrong? Mostly the dc dc converter evaluation boards available in the market control their output voltage using potentiometer, resistor trimming, I2C programmable. What kind of strategy should be used to control with Microcontroller using voltage divider, current amplifiers, ADC, PWM generation. There is I2C but the complexity of the coding will be increased. I am not much into coding. For suppose as shown in the figure both the converters are given 36V input and charge the batteries connected to each conveeter output. How can I control the charging here digitally?
33431
I am using  64-pin Microcontroller. I want to configure the IO pins in RUN Mode, Sleep mode and Reset mode. For used pins, say IO, I2C and SPI pins, output pins, please tell me what should I give for the below questions during each modes (Run, Reset and Sleep):  Whether input or Output pin? Whether internal pull-up or pull-down to be enabled? To drive High or Low?
12425
USB is a popular standard and I was wondering whether there is some way to connect two or more computers using USB ports rather than the Ethernet ports.