So I know that for a USB port type A there is 2 ouputs/inputs. I'm working on a simple electronic circuit and I would like to ouput datas on to my computer so a program could work with it. How (without it getting too complicated on the circuit side) can I just choose the output of the USB port and read the input just on the on/off level?
Thanks
What you want is the www.Nusbio.net device.
it is an USB device that give any .NET programming languages access to 8 gpios and also SPI and I2c bus.
USB is more complicated than what you are describing. It sounds like what you really want is a serial port, where you can use the TX and RX lines as your output and input to the PC, or manually control the modem control or GPIO pins. You can still do this with USB via a USB to UART Bridge device.
If you are simply looking to toggle an I/O pin, some of these devices also have general purpose I/O pins for this type of thing. You can set it to low/high from the PC if it is set to be an output and read the I/O value if it is an input.
You can talk to it as a serial device from your computer using normal serial communications such as POSIX method for Linux or OSX or the Commuincations API for Windows. In this case you can also set the flow control to manual and use the RTS/CTS pins as GPIOs.
You cannot directly control the USB inputs and outputs like you want to do. However, there are various solutions that involve connecting a USB device to your computer and sending commands to it that use its inputs and outputs. One such solution is called Firmata.
Related
I'm trying to configure/write VHDL code that would let me output or input data from the USB port on a Basys3 FPGA board. Problem is I have yet to found any threads or questions that talk about this topic.
The nearest thing to an answer I've found is this:
Provide input data to FPGA using USB
and it does not contain what I'm looking for.
Any clues anyone¿?
The Basys3 board has a usb-uart bridge chip as described in the reference manual. This will appear to a PC (or any device with a usb host and the appropriate usb-serial drivers) as a virtual com port. Sending data to and from a PC com port is quite easy.
You will need a uart implementation on the FPGA. There are lots of example designs on the web. One way is to implement a soft core microblaze processor with a uart peripheral in the FPGA. This example looks like it includes foundation for the functionality you desire.
The simplest implementation from the PC side is using a terminal program such as putty, Tera Term or realterm. Most languages include com(serial) port libraries or bindings. This type of interface tops out at a raw bandwidth of around 3-12Mbits per second depending on the drivers and implementation.
Read the manual for the Basys 3 board. It will explain how you can interface with USB devices plugged into the USB port. Be warned, however, that your options are pretty limited.
Short version: if you plug in a USB mouse or keyboard, they will be exposed to your design as an emulated PS/2 device. USB storage devices can be used to configure the FPGA. Other devices are not supported.
We have an NXP chip (LPC1778) and we need a way to program the firmware via FTDI over USB. We are interested in a way to do this via command line on Linux. We are able to do this via flashmagic on Windows. Any advice is greatly appreciated. Thanks!
For reference we are able to program it over the serial port using this utility:
lpc21isp -wipe -control -verify -debug2 /path/to/hexfile.hex /dev/ttyS0 57600 12000
I am new to embedded programming and FTDI technology.
Utilities suggested by Clifford:
http://sourceforge.net/projects/nxpprog/
http://www.windscooting.com/softy/mxli.html
BACKGROUND
Just for those that are interested, we want to issue terminal commands to a board via serial AND program it via that same port. Our DTR and RTS pins are connected to the boards reset button and the RST is connected to the NMI. When connect using the java RXTX library it asserts those lines and we end up resetting the board which is not desired. We were hoping that if we could program using the USB port/FTDI bridge we could avoid resetting the board but it seems we would still need to use those lines to put the NXP chip into programming mode regardless so this might not be a valid solution.
The use of "USB FTDI" or FlashMagic is irrelevant. The FTDI is simply a USB-UART bridge to provide a serial port.
The NXP parts themselves include a serial bootloader that uses a specific ISP protocol for in-system programming. Your part's data sheet may detail the ISP protocol, although details and app-notes seem to be hard to locate. However Google "NXP linux ISP programmer" and you will find at least two solutions: mxli and nxpprog.
Not all NXP part's ISP are the same. Some present as a USB drive that you simply copy the binary file to. That however is no applicable over a serial interface (USB or otherwise).
If I had a RFID reader that sends a bunch of keystrokes through USB like a HID, how would the COM port interperate that if I used a USB to COM converter? What would the COM port see?
You should see the "keystrokes" from the rfid device.
At the link level, the converter should take care of speed mismatch issues. It does this via an internal buffer or by throttling the sender.
But the HID protocol is more than simple keystrokes. So either the additional information will be suppressed by the USB-COM converter or it won't be. This issue may also be converter-dependent.
In this sort of HW mashup, the best thing is to try it and see. (And then write a blog post about what you discovered.)
What is your overall goal? What sw are you trying to connect the RFID reader to?
Added I agree with #Turbo J's point: most every USB-COM converter acts as a USB device. As such, if you connect them to another USB device, nothing will happen since you're using them "the wrong way around."
You'll need to find a USB/Host to COM converter. The usual name for such things is "computer" -- a used laptop may be your best bet if you want to continue down this road.
On USB, a device can only talk to the host.
The RFID reader is a device. The USB->COM converter is a device. They cannot talk to each other wihout a host.
Conclusion: If you want the RFID data going out of the COM port, write a program which does that - by reading the HID data from RFID device and writing to the USB COM port.
Probably nothing. COM ports are usually very low speed things (you can usually tweak them up to about 115kbps. USB ports are (by comparison) incredibly high speed ports. I think the lowest speed USB is like 1.5mbps.
The more important question is how you are going to make the physical conversion.
You have an RFID reader that has a usb plug on it. Are you going to chop this off and solder a db9 connector on the end, which you are then going to plug into an USB to COM adapter and try to read serial data off the com port?
You are adding in one more step into it that you don't need to (you're taking up an usb port anyway).
I am working on Xilinx Spartan 3E platform, using this development board:
http://www.xilinx.com/products/boards-and-kits/HW-SPAR3E-SK-US-G.htm
My program operates on certain data and then provides output. I wish to transfer the input signals externally. The input data is a stream of 8-bit signals.
So, how do I send the input signals from my laptop to the FPGA via USB? Does Xilinx support this or is there standard software to do this?
Thanks.
It sounds like you are describing a uart more than a native USB interface. You can get a USB to logic level serial adapter that will let you easily transfer data to and from a Pc at up to 921.6k baud. A uart/serial port is easy to implement in the Fpga and PCs are easy to use with serial ports.
Here is the cable:
http://www.ftdichip.com/Products/Cables/USBTTLSerial.htm
If you have a development card it is very possible this type of interface is present.
On the software side you can use your programming language of choice as if it was interfacing with a seal port or use a terminal program like hyper terminal or Download teraterm http://ttssh2.sourceforge.jp/
Updated response:
100Hz is not a hard interface to make. At that rate you should use the serial interface if at all possible. The board you referenced has 2 full RS-232 connections. At that point you only need a way to connect that to your computer. If you have a PC with RS-232 connectors you only need a cable if you have a newer computer without you need a RS-232 to USB translator cable (like this one: http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=768-1014-ND or google rs232 usb). This will give you a virtual com port on the pc to interface with the previously mentioned terminal programs or your custom software.
Update 2:
on the resource tab of the development board page you linked to there are several UART based fpga designs that you should be able to use as a starting point.
i.e. the "PicoBlaze Processor SPI Flash Programmer".
That board doesn't provide easy access to the USB interface from the FPGA as far as I can tell. It's just for configuration and debug.
Some of the newer boards and tools do allow something called hardware-in-the-loop testing where the simulator can upload data to the FPGA, wait it to calculate the results and then pull the data back. This is relatively common when using Xilinx's System Generator product as the simulations can be really long.
But I think with that board you'd be better off using the on board RS232 port to get data to and from the board. You will have to build the infrastructure to do it yourself though.
This may also give you some ideas:
http://www.1pin-interface.com/
I'm looking to control a mains powered light from a simple relay switch connected via USB to the computer.
The relay switch isn't even a USB device, it's just a simple switch that requires the USB voltage to turn it on. When the voltage drops below a threshold, the switch will turn the light off.
My problem is that I can't control the power output of a USB port. I'm happy to do it using any language on Windows or Linux (but preferably Java because I'm used to it).
Unfortunately, in most cases you cannot control the power supply to the USB port. The power supply is usually hardwired through, and not switchable in software. You can send a reset to a USB device, but that won't work in your case.
There are a number of projects on instructables that do similar to what you describe, but unfortunately they seem to either be quite complicated or require expensive parts.
EDIT: There is actually a product currently in the news which would do want you want, but it doesn't appear to be shipping yet: http://www.pwrusb.com/
EDIT (again): Apparently you can do this with some usb hubs. This post sugggests the Linksys USB2HUB4 is one that works.
EDIT (and again): Apparently there are a number of similar questions, but there don't seem to be any more useful answers:
https://stackoverflow.com/questions/405269/custom-usb-device-that-disables-power-to-usb-devices-plugged-into-it
Power off an USB device in software on Windows
Is there software or code to alter USB power output
Can I write a program that swiches USB on/off
Most of the USB to Serial or USB to RS232 $10 converters support hardware handshaking. Use one of those as a single channel digital io.
Connect your transistor that will drive the relay to DTR on the converter board and command DTR ON/OFF with the converters driver.
A 2N7002 is a good transistor to use (FET actually) since it will work from 3V and doesnt need any resistors anywhere.
Here is a complete solution.
It uses an Arduino board, with a USB connection, (and Uno for example) to control the relay and combines this with pfod (Protocol for Operation Discovery) www.pfod.com.au which will let you control the board/relay from either the Arduino IDE SerialMonitor, or a terminal window (TeraTerm) or a Java program. The message protocol encloses commands in { }, think simplified html for micros, and provides numerous screens, menus, sliders, text and numeric inputs, etc. A detailed protocol spec is available
See Garage Door Remote for a detailed example, with full Arduino code and an example of controlling the relay from TeraTerm as well as the Arduino IDE SerialMonitor.
There is also an Android app, pfodApp, which will do general purpose control via bluetooth, or wifi/internet with 128 bit security. The pfodApp does all the Android stuff, you only need to code some simple strings in your Arduino code to get any menu system you want. See www.pfod.com.au for numerous examples.
You need a USB-GPIO microcontroller:
Adafruit FT232H (about $15)
Arduino Nano ATmega328 (about $7)
See this answer
I would suggest placing a separate Raspberry Pi unit with a wake-on-lan feature activated so you can ping it off and on.
You could do it by combining these two products from Pololu, for about $25:
Micro Maestro (assembled)
Basic SPDT Relay Carrier with 5VDC Relay (Assembled)
The Maestro is mainly a servo controller but you can set any of its channels to be simple digital outputs instead. The output can be controlled from the Maestro Control Center software or you can write your own software. A digital output from a Maestro is suitable to turn on the relay on the relay carrier. The relay could be powered from USB through the Maestro; I think it draws about 100 mA of current so that probably will not be a problem for most USB ports, though it would not be USB-compliant because the total current drawn by the Maestro and the relay would be over 100 mA. You could supply your own power source for the relay if you are worried about that.