I don't have much konwledge in electronics. i wanted to turn on/off led connected to usb port using program. usb port consists 4 line (data+,data-,voltage ,ground) if i connect voltage and ground lines to led , it will glow. i've been searching on internet this issue and i find that it is not possible to control led connected to usb using program because supply over datapin is too low which can not be used to tun on off led.
but what if i connect my led to vol and ground pin and control the entire power supply of usb port , i guess it is possible to control led using program. there is a way to disable and enable power supply over usb port.
i also want to know is it bad to follow this approach. does it damage usb controller to frequently enable/disable power supply.
Algo :
a = Get_input_from_user() ;
if(a=="ON")
turn power supply of usb port ON.
else
turn power supply of usb port OFF.
this thing is certainly possible using extra hardwares, i don't want to use any extra hardware.
The power for a computer's USB ports is generally not software controllable. In most cases, the power pins of your USB ports are wired directly to the 5V rail of your power supply (usually through a polyfuse), so there is no way to switch them on and off.
Some powered USB hubs do support switching power to their ports, but you said that you didn't want to use any extra hardware, so you're out of luck.
you can use any basic Arduino board to do this there is a complete IDE free and a LOT of sample code that will do what you want out of the box
you can also use a COOL board.
Arduino Compatible code is available for the Teensy
Software Development Tools HERE
You can use an external power supply (the Vcc and GND pins of the USB port in this case) with a resistor to power the diode and connect a transistor in the middle working as interruptor. Then, yo connect the base and emisor to de data+ and data- of the USB port.
this page doesnt let me upload images.
Sorry for the quality of the drawing but all I have on the computer is paint.
For a more stable performance make sure to make R1 low enough so that transistor is on saturation mode when data pins are ON but not so low that transistor gets burnt (I dont really know what is the voltage level of the data pins on the USB port, sorry).
To choose a proper value of R2, you need to know the current you need to power your diode. It's calculated acording to Ohm law:
Idiode = (Vcc - Vce,sat - Vd) / R2.
Where Vce,sat is potencial diference between colector and emisor when transistor is on saturation mode (it is found on the transistor datasheet on the manufacturer webpage, usually around 0.2V) and Vd is the normalized potencial difference of the diode (the same, but this time around 0.6V).
Note that data- and GND pins are connected. I am 99% sure that this won't harm your USB port, but use it at your own risk.
I would test it out using another external power source first anyways, just to make sure you connected everything properly.
Related
Im having issues with my TI LAUNCHXL-F28379D. I have it connected to the laptop I am trying to send data to/from via pins P19 (SCIBRxD) and P18 (SCIBTxD), as well as GND and 5V via J16, using a USB Type B cord to which I sautered pin connectors. I'm sure power is being supplied to the board as when I plug the 5V cable of the USB cable, the RGB lights and 3 other small ones turn on. However, the Computer does not recognize ithe controller at the port - it only recognizes if if it is connected via the board's Mini-USB port. I've also written a C Program which opens the COM port and reads data - but this does not work without my knowledge of the COM port number, usually found in Device Manager. I cannot get any further in my project without the port number and it is very annoying. I will attempt to resauter a new USB cable, but if there are any other possible solutions, or if I'm doing something wrong, please let me know.
Absolutely all feedback is appreciated!
The SCIBRxD and SCIBTxD pins belong to the SCI peripheral in the microcontroller. This peripheral implements a UART port (a.k.a. COM port, a.k.a. TTL serial port). It is not a USB port. Nothing useful will happen if you connect it to a USB port, because it is not compatible with USB in any way.
USB-to-UART adapters (a.k.a. USB-to-serial adapters) do exist. There is one built into the LaunchPad. The UART side of the adapter is connected to the SCIB pins, and the USB side of the adapter is connected to the USB port.
I am very new to C and embedded programming.
I simply want to have my main thread wait until a usb device has been plugged in to my embedded device.
However, no matter how hard I look, I cant find documentation or examples about how to check if the usb has been plugged in.
I am using a ATSAM4S8B.
EDIT:
Actually I think the usb capabilities are built into the chip, I can use Atmel ASF libraries.
I am hoping that there is just a library function I can call to see if the usb has been connected too but I can't find anything like it.
There are two ways of detecting USB connection:
waiting for usb events occure and special USB flags to fire in hardware registers, which will signal if initiating process started. This solution depends on a particular chip you use and firmware burnt into MCU.
use sense IO pin. Attach USB 5V through 1k resistor to a pin of the MCU. High level on the pin will indicate, that USB was connected. Dont forget to use high value (>10k) pull-down resistor, which will pull the input low when USB disconnected.
I wasted countless hours and I am completely clueless on a problem with two xbee S1 modules.
I have two 802.15.4 modules which can reach 1.6km.
I have one connected on PC through USB (5V( and a 3.3V linear regulator, scope shows 3.289V with some ripples of 0.2v.
I have another one connected on a battery powered source, again with linear regulator, scope shows 3.299V, very stable voltage.
They are set up for the same PANID and channel, I use the ATND command to discover each other.
There is no chance they find each other, resets, etc will not help.
I have a scope connected, the voltage stays stable at 3.3V.
I have a USB to serial converter connected to both chips (3.3V ttl level of course) and BOTH can be reached through serial.
I can send AT commands to both, so both are powered on and 'should' work.
If I now connect the battery powered one to the same power source which is connected to my PC then suddenly they see each other and everything works as it should.
It is not depending on range, I already made sure of that.
I am left clueless, it makes absolutely no sense.
Anyone with an idea would be very welcome.
(Note: your question is probably better suited for https://electronics.stackexchange.com/ I'm an EE so I'll go ahead and try to answer though.)
First, make 100% sure the battery is actually good, and the voltage isn't getting loaded down when it tries to transmit. You can watch the voltage on an oscilloscope to check. (I know you looked at it on a scope, but make sure you do it during operation, not during idle.) If it drops then the battery can't supply enough current. If there's heavy RF noise then you need bigger ceramic power supply bypass capacitors. Those are my top guesses.
If the battery is good, then it's also possible that the antenna connection is bad on one. When they share a power supply, RF might be coupled through the power or ground wire, so they can still talk to each other through the wires instead of through the air. If you try powering them BOTH from the battery, and they start working, this might be what's happening.
I would like to control some physical engines, switches on/off, lights through a self written C API.
I already have a very general overview of how to achieve this:
Use the kernels abstraction, write a driver on it and use this as control. The driver itself has to manage incoming bytes and interpret them (depends on port).
I personally would prefer to use a USB port because I can use my MacBook to develope.
But I know that the protocol is quite complicated. However here are my specific questions:
Which port is good to use (is USB a suitable option?)
Could I simply wire a engine to the USBs power cables and connect the data cables to a power swith or do I require an extra board?
Are there better docs for OS X, BSD or gnu/Linux?
Bodo
To control physical engines, you have to add at least a power supply board, there is no way that your USB port drive a DC motor (maybe a LED).
The easiest I/O port on a computer is the LPT (parallel port), but this is a 'very' old thing. I agree that USB port is most convenient but in order to work easily with it I advise you to buy a small card.
This Usb board (or anything of the same kind) can do the trick.
I hope it could help you,
I have successfully talked to the computer from an Arduino via serial USB port and I had the idea that I could make a keyboard or mouse with the arduino. Say I wanted to translate the computer's mouse 1 pixel to the left. What message would I have to send over the serial line in order to achieve this?
Google is a wonderful thing. "use arduino as mouse" returns 1.7 million hits. The third hit on the list takes you to the Arduino Playground for an example using the new Leonardo board.
Note:
The Leonardo differs from all preceding boards in that the ATmega32u4 has built-in USB communication, eliminating the need for a secondary processor. This allows the Leonardo to appear to a connected computer as a mouse and keyboard, in addition to a virtual (CDC) serial / COM port.
Assuming you don't have that board, here is another site for some other specific boards and yet another that is log for a project including hardware and software for older boards.
Hope this helps (and is a better answer to the question).
You would have to reconfigure the USB interface chip to appear as a USB HID endpoint.