I am using LabVIEW to program a system that interfaces through a mccdaq(web tc). I am wondering how I can (through code) turn on and off an LED with the push of a button. I am able to use the DoutBit VI in order to make the LED blink with a push of a button, but not stay on. I have tried using Dout instead of DoutBit, but I am being told that my port is configured for an alarm. (Which it's not).
I was able to figure this out on my own. I needed to configure the channel within LabVIEW and send the outgoing port to my Dout. Then I was able to send the digital signal to my LED and keep it lit for a period of time. I was able to turn it on and off by simply sending it a hex digit (binary conversion) for the ports that I wanted to enable / disable. (For example if i wanted to enable ports one and two, the hex answer is 3 ("11" in binary).
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I'm not even sure whether I've framed this question correctly. Let me explain my situation.
I have an Application hosted in a OpenVMS environment which is being accessed via Telnet. I'm in need to programmatically accomplish certain tasks.
So far I could send and receive messages using a C# Telnet Client. I am able to execute tasks by sending commands and receiving responses. But for one task, I have to edit a Form to change some information. The command looks like below
>modify page <page_no>
As soon as I enter the above command, the entire terminal gets loaded with this Form, I have to use page-down to go through the fields, press enter to edit the text and use Ctrl-Z to save it.
I'm not sure how to accomplish this task programmatically.
I'm not familiar with telnet or VxWorks. I'm not sure the above is a feature of Telnet or OpenVMS. Kindly help.
This should be easy to figure out thanks to the clear text of telnet :D It shouldn't matter what platform your target is running. All you have to remember is that special keys like ctrl-z or page down, are just chars in the data stream. Ctrl-z is typically 0x1a, and I am not sure what page down is off the top of my head, but here is how you can figure it out:
Get wireshark http://www.wireshark.org/ and install it if you don't already have it.
Start wireshark up and capture all traffic on your NIC that will carry the connection to the target.
Start a normal telnet session to the target and issue all of the commands (including the page downs and the ctrl-z).
Stop wireshark capture and then filter out everything except telnet communication between you and the target.
Look at the data that was sent to issue the ctrl-z, and page downs.
Put those chars in your telnet stream when you are ready to issue those commands.
Easy.
I have an embedded system that controls a motor using pwm and some other things, I send commands through a serial connection, which is connected to a Fastrack Wavecom Supreme GSM Module. However, the module connected to the embedded system (the client), fails to send the message to the server module.
I have been able to send messages back and forth between the two wavecom modules, however, when I try and send from my PIC18F45k22 to the wavecom module, it fails.
Any ideas of what could be going wrong?
You did not specify what type of serial communication you are using. For instance, if you are using the PIC's SPI module you may be sampling on the wrong edge of the clock. There are at least 2 common SPI modes widely used and 4 all together. If you are using the PIC's UART there are "a whole bucket full" of setting that may be off. Speed, number of bits, in band signaling, out of band signaling, parity, ect.
I have a Netduino Plus with at transeiver attached via SPI. I would like to reset the transiever every time the Netduino restarts. Is it possible to programmatically power on/off the 3V3 pin?
I would recommend using a FET (controlled by one of the I/O) pins to enable/disable 3V3 power to your transceiver. When you say transceiver, I think "more than a few mA" :)
BTW, we took this feedback into account with the new Shield Base module for Netduino Go. It has an integrated FET on both 3V3 and 5V power headers, so you could enable/disable power to your shield in code. Once the new Ethernet go!bus module ships and the Shield Base comes out of beta (soon), your solution can be redeployed to Netduino Go + Shield Base with few/no code changes.
Chris
Secret Labs LLC
Looking at the circuit diagram ( http://www.netduino.com/netduinoplus/schematic.pdf ), I can see only the Micro SD Card Slot having its power controlled programmatically. You could rig up a relay to control it (via a transistor, of course) instead, or if the transceiver uses less than 130mA (the current limit of the device shown: http://www.datasheetarchive.com/BSS84W-7-F-datasheet.html) you could copy the circuit from the Netduino Plus. Buying a relay shield looks like overkill, but you might have other uses for it.
Have you looked into resetting the transceiver programmatically instead of the brute-force method of power-cycling it?
Just to provide another view. You could use a transistor powered off the netduino RESET line, this will reset the device every time the netduino reboots. Or you can just link the transistor to a spare digital pin and power it in code..
What specific SPI device are you using? You mention that it's a transceiver but we could probably provide better information if we know the exact part number. If your device requires less than 8mA the Netduino Plus specs seem to indicate that one option could be using a digital output pin as the power source.
Unfortunately Secret Labs don't use exactly the language I'd expect and call out the sink and source current maximums so I would contact them directly first to see if you risk blowing your chip. I'll see if I can get an answer from them and amend this post if/when I do.
Update: Sink and source current is the same on the Netduino. See my post on their forums about sink vs. source current for a more in depth explanation. So, if your device can run off of just a few milliamps you should be able to use a digital I/O pin to power it.
Also, a lot of devices have enable pins. You can usually reset them with that line instead of pulling the power if that helps. Sometimes with flaky hardware it is better to pull the power though.
I am working on a project which uses a PIC24FJ64GA002 mcu.
I am working on a bit-banged serial communication function that will use one wire to send data and then switch to receive mode to receive data on the same pin. A separate pin will be used for clocking which will always be controlled by a different board (always an input). I am wondering is there a way to configure the pin for open-collector operation that that it can be used as an input and and output or do I have to change the pin configuration every time i go from reading to writing?
You need to change the direction of the pin each time by using the TRIS register. If the pin is set up as an output, reading the PORT register will most likely only tell you what level you are driving the pin to (assuming there is a high impedance on the pin). If the pin is set for input, you won't be able to drive your desired output value.
Also, make sure that you read incoming data using the PORT register, but output the data using the LAT register. This ensures that you don't suffer any issues if your code (I assume you are programming in C here) gets converted into bset/bclr/btgl instructions which are Read-Modify-Write. If you are writing in assembler, the same rule applies but you know when you are using these R-M-W type instructions. If you want more reasoning on this, please ask.
If I understand the parallel port right, sending data from (D0 to D7) simultaneous, but that it can control the sticks individually?
example:
D0 = Input
D1 = Input
D2 = Output
...
...
...
D7 = Input
would it work?
what I want to do is to both send and receive data simultaneously.
Data wires (D0-D7) are being read or set simultaneously. For various tecniques for bidirectional I/O read the attached articles:
Standard parallel port: http://www.beyondlogic.org/spp/parallel.htm
EPP: http://www.beyondlogic.org/epp/epp.htm
ECP: http://www.beyondlogic.org/ecp/ecp.htm
This site is a good source for programming the parallel port.
The basic idea is that you need a DLL, add-on or library that allows you to access the I/O Ports of the PC. For Windows XP on up you need a specific driver that will allow you do this as the OS doesn't offer access out of the box.
The Parallel port will generally reside at one of three address 278,378, 3BC. This port. have the bytes you are reading or writing.
The (base)+1 port allows access to the status bytes. IE. 279,379, 3BD
The (base)+2 port allows access to the control bytes. IE. 27A,37A,3BE
The parallel port documentation will tell not only how to implement the common modes (like bi-directional) but how to control the port at the byte level to implement your own custom.
Back in the day there was only the standard mode available. You pump out your bytes at the (base) port. Some application, like mine, manipulated individual bits of that ports as form of cheap Digital I/O Controller. We did use the status and control bytes as additional inputs and outputs. There were commands you can send to the Parallel Port chip configure the modes precisely.
Today there are are hundreds of sites with example of using the Parallel Port to solve all kinds of problems. I would be surprised that one of doesn't have something you can use for you specific application.
Again the book I recommend starting with is Parallel Port complete. It tells just about everything you need to start with. If your application is too esoteric for that book it will give a springboard from which you can find the exact setup you need.
Of course by sending a number that has just the required bit set (2n) you'd get the expected result.
I'm not sure about bidirectional access though. I guess it's achieved by using control pins along with the data pins but that's just a guess.
Parallel ports doing EPP or ECP only allow D0-D7 to be all input or all output. Trying to do otherwise may fry your hardware.
See http://www.nor-tech.com/solutions/dox/ieee1284_parallel_ports.pdf, page 6.
However, parallel ports have several control lines that may be useful if you only need a small amount of input/output in the "other" direction.
I believe its bit 5 in the port's control register (base address + 2) that switches direction. (no hardware line attached)