I was just learning about the port configurations of the GPIO pins. I came across the open drain configuration, and I was bit confused. I could not understand this properly. When this should be enabled or disabled? Should this be always enabled when the port is configured for output while transmitting?
120915
I want to understand the concept of open-drain ports like port P0 of the 8051 microcontroller. Why do we need to connect pull up resistors to the port P0?   I have basic knowledge of MOSFETs and other electronic devices.
50575
I am trying to figure out what devices are in my desktop computer's PCI slots. I need an open slot for installing a wireless adapter, and I cannot figure out which ones I can take out, and which ones I can't.   If there is a sound device in one of the slots, I have no problem with removing it, as I do not need my speakers for this computer.  Any help with determining which slots have what is appreciated.  Thanks.
95833
I'm looking to drive a  from an Arduino. I've found a question about , which includes a circuit that looks perfect for this kind of situtation:    What I don't understand is how to select a MOSFET for the job. What properties should I look for, if I know my logic level, device voltage and device current?  In this case it's 5V logic, and the load runs at 12V / 500mA, but it'd be nice to know the general rule.
73090
For someone trying to learn about FETs, it seems there is no consistency in terminology (unless I am reading things wrong.) I am trying to understand the FET as a switch (for power applications.) It has become clear that you want to operate a switch in the ohmic region. To get to the ohmic region you would need to go from cut off -&gt; saturation -&gt; ohmic region. TI refers to it like this in an   From this I implied that the 'linear' region is in fact rather confusingly the saturation region of the FET as shown all across the web for a FET curve:  However, when I went to wikipedia I came across the following image:  This is saying the exact opposite of what I understood which is saying that the ohmic region is the linear region. Infineon has an app note around FET switching, titled  They refer to the linear mode as the saturation region as shown from this:  So what is it then? Also just to be clear: Is the reason we want to minimise time in the saturation region with an FET because here we have a VDS and an ID current flowing through the FET, whilst as soon as the FEY reaches linear region, it's VDS would fall close to 0 and hence minimise losses? When we say the FET is saturated, it means for a given Vgs, Vds makes no difference to drain current (because channel can't let more electrons to flow?) Shouldn't the ohmic region be called saturated? Since increasing VGS makes no difference to drain current as the ID is now limited by the circuit and not the FET? Edit: Answers in electronic stack exchange say it is the saturation region:
102998
Kind of hard to explain but I noticed when straceing the PID that has the socket open I cannot see any of the communication. How can I sit in the middle of a socket file to watch communication?
46890
While reading a , I found the parameters Input clamp current / Output Clamp current. Where do I consider these specifications?
108520
I just portscanned my system with nmap and got the following result:  PORT    STATE SERVICE 25/tcp  open  smtp 631/tcp open  ipp   what are these services and how i do disable them? probably i don't need them.
35242
My problem is about AND-gate when its inputs are open. I want to know: What is the output when inputs are open? The output is Z (open) or 0?   What is your idea about this AND-gate transistor structure?     ()  My answer to the above structure is that the output is 0 when the two inputs are open, or at least one of them is 0.
111912
I'm looking for feedback and improvements on my design below. Specific questions are at the end. I created this as an attempt to answer my own, . From my feedback there, it seems like I needed to be more clear in my requirements. These are screenshots from Eagle. If there's a better way to share, please let me know so I can correct it. Entire board  The overall purpose of this board is to translate between 12V logic, and 3.3V logic. The top portion of the board represents the 12V side. The LEDs are placeholders to indicate whether the 12V signal is HIGH or LOW. In practice, these would be replaced with more , requiring up to 3A. The switches are also placeholders, allowing one to manually turn the 12V signal on and off. They are only for test purposes, the &quot;real&quot; 12V signal would be coming as the output from other relays. The bottom half is the 3.3V side. This will be connected to a  (BBB). The board will connect to 2 output GPIO pins and 2 input GPIO pins of the BBB. Overall, I want to translate the 3.3V I/O from the BBB to the 12V signals on the other side (to control more relays and read their signals). I have designed 3 modules to control both directions individually, and together. 3V3_TO_12V Module  This module converts the 3.3V GPIO output from the BBB to a 12V signal on the other side. When the 3.3V signal is low, the 12V signal is low. When the 3.3V signal is high, the 12V signal is high. To do this, the 3.3V GPIO output is connect to a , which turns a  relay on and off. This switches the 12V power as output of the module to be used elsewhere. 12V_TO_3V3 Module  This module converts a 12V signal to 3.3V signal, to be read by a GPIO input from the BBB on the other side. When the 12V signal is low, the 3.3V signal is low. When the 12V signal is high, the 3.3V signal is high. To do this, the 12V signal simply turns a  relay on and off. This switches the 3.3V power to be read as input by the BBB. DUAL_12V↔3V3 Module  This module combines the previous two modules to create a bidirectional translation. If the 12V side is high, the 3.3V input to the BBB GPIO should be high. If the 3.3V output from the BBB GPIO is high, then the 12V side should be high too. It's similar to a logical OR, if either side is high, the corresponding signal on the other side should be high too. A single 12V signal has to be split into individual input and output signals on the 3.3V side for the BBB. Questions  Is the  and  relay combination overkill for having the BBB GPIO output control the 12V power line? I like the isolation and safety it provides, but it seems too much (in terms of cost and board space) Is there a better solution for the 12V to 3.3V conversion. I like the simplicity of the  relay switching a 3.3V signal, but it takes up lots of room. Does the DUAL_12V↔3V3 Module (which combines each translation direction) even make sense? This seems wasteful to use 2 relays and a high side driver, but I haven't found simpler solution that achieves the same result. Should I add pulldown resistors for the BBB GPIO inputs, or are the internal pulldown resistors good enough?  Any other feedback is welcome. I'm new to electronic design.
82060
I'm quite blank when it comes to electronics, but am trying to learn...   So I bought a  from Banggood to get some solder practice.   As you can see from , the leds will change color and turn on and off in different patterns.    question already establish that two pin RGB leds most likely contains some kind of micro chip, but it doesn't say anything about how they can be controlled.  The chip on the board is a STC15F204AE, and I guess that's the one responsible for creating the patterns. But again - how?  Is it just a fixed sequence pattern in the LED, and then the chip ensures that each LED receives power right after the previous, or is the LEDs addressable some how?
65808
I've gone through the complete , searched SE and on google, but I cant seem to find this information: Whats the output Voltage of QA..QH just after power-up when G (Output enable) is pulled low, but no data have been clocked into the shift register?
49032
For an ideal OpAmp the voltages at the inputs are said to be of equal value and the currents 0, however, for we also know that $$V_\text{out}=A(V_p-V_n)$$ but if the voltages are the same the output should always be 0!  I know that what I'm saying is wrong, but I don't know where the loophole is, and I can't find it anywhere.
112137
How to compile and run open cl codes on intel i5 processors having intel hd 4000 gpu unit??? Open cl has been istalled in /opt/intel/opencl and versionis ubuntu 12.04. Any help would be of great help... Thanks
38473
I just want ask how the socket in the image is called?   I couldn't really find and the closer I could get is only Raspberry's module.
90837
I am trying to route a pic32 chip to a  chip and having a bit of a hard time getting all 17 address lines and all 8 data lines connected. I am trying to tie the first 16 address pins to portB pins 0-15 and the data pins to portD 0-7.  After thinking about it for a while I realized that I am probably making my life more difficult by trying to line up rb0 with a0, rb1 with a1, etc. All I really want to be able to do is write a 16 bit value to portB and have the majority of the address loaded and ready. If I make pin assignments based on ease of routing, the logical address will be different between the mcu and the ram, but it should at least be consistent. Since nothing else needs to communicate with the RAM, I don't think it will be a problem if the mcu asks for address 0x101 and the RAM gives it address 0x110.   However, I wonder if it is a good idea. If there is some structure internal to the RAM designed to make sequential reads more efficient, or something like that, then I may want to go to the trouble of routing them 1:1. The pins arrangement on both chips fees somewhat random to me, so it would make it a lot easier on me if I could ignore the particular numbers. Is there any good reason why I should or should not do that?
26440
Im trying to figure out the current limitations of a mosfet(SISA18ADN) I'm planning to use to check how much headroom I have.  The datasheet states Continuous Drain Current that it can handle as 12.1Amps at Ta=70degreeC during 10seconds, and 38.3Amps at Tc=25C with no time specification.  But in the Safe Operating Area graph, apparently for DC it can handle less than 0.2A at 10V..? Am I getting something wrong when reading the graph or when reading the specs?  The Safe Operating Area graph is here:
21312
Say I had a laptop [Correction: notebook, don't want my thighs medium rare], any OS, and it has an HDMI port built into the side. Would it be remotely possible to hack it into an input, provided it wasn't already designed for that? I would figure all video ports operate straight off the graphics chip, however, are there ways to override that functionality on the driver level? Driver hacks already exist for plenty of things such as the classic example: Bluetooth adapters (so we can play with our PS3 controllers and save a buck) However, is HDMI one of these tamperable interfaces? As far as the interface standard is concerned, are HDMI ports designed to be either way or are they Input/Output specific?