Count time between 2 readings from serial port... help!.

Hi guys,
I am using my application to get the readings sent by microcontroller from serial port. It works perfectly. But i have the problem, the pic uses 16bits counter, and sometimes i measure frequency lower than 15hz (65535-->16bits). Thats why I thought to measure the time between each pulse that it recieved in serial port. So i could multiply the reading about the time which spend in arrive to serial port. I know if any pulse spend more than 15hz, i should add 65535 to this reading.
Then, the idea is count the time spent between each reading in serial port. SInce pics count and later send each turn.
I dont know if it is possible, and exist any easy way.. Can ayone help me?.
I would like to see any example of it, always it is possible.
Regards, Fonsi.
Attachments:
capture.GIF ‏19 KB

You're not going to be able to get even close to 1 usec resolution using the built-in time functions though I don't see any of those in your attachment. The windows clock is simply not that accurate. If you need to precisely time your serial reads you might want to look at using the timed loop. You can set the period of that to 1 msec.

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    hello everyone, i am recently working one a project which require communication between pic16f877 and PC. My pic continuiously measure a voltage and send the result (a byte ranging from 0 to 255) to the rs232 port. One the pc side, my java program keep reading the serial port and it works for values 0~127 and 160~255. But if the byte value is between 127 and 160, it cannot received correctly, i get something like 375,8224,or even 65532 etc(no obvious path but more likely to be 300+,700+,8000+ or 65500+). I have been trying very hard to solve this and i think the problem is due to the pc software. I am feeling so frustrated and any suggestion will be much appreciated.
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    --mengyao                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       

    fumengyao wrote:
    hello everyone, i am recently working one a project which require communication between pic16f877 and PC. My pic continuiously measure a voltage and send the result (a byte ranging from 0 to 255) to the rs232 port. One the pc side, my java program keep reading the serial port and it works for values 0~127 and 160~255. But if the byte value is between 127 and 160, it cannot received correctly, i get something like 375,8224,or even 65532 etc(no obvious path but more likely to be 300+,700+,8000+ or 65500+). I have been trying very hard to solve this and i think the problem is due to the pc software. I am feeling so frustrated and any suggestion will be much appreciated.
    p.s. : i used Bufferedreader.read() in my program
    --mengyaothis may not matter in your case - but don't use a Reader, use a Stream (BufferedInputStream maybe)

  • Stoping VI inbetween when program seeking data from serial port.

    I have an application in which I need to read data from two serial port one after other.
    One read will read 14 byte and other 08 bytes(Just info).
    Now in between if user need to stop the VI then how to stop it?
    Kudos are always welcome if you got solution to some extent.
    I need my difficulties because they are necessary to enjoy my success.
    --Ranjeet

    A state machine could do this easily.  Just have a state to check for the stop (or any other events).
    There are only two ways to tell somebody thanks: Kudos and Marked Solutions
    Unofficial Forum Rules and Guidelines

  • Start a program with a signal from serial port

    Hi, my program need to continue when it's gets a signal from the
    serial port, I've understand that i need to use Java Communications 3.0 API.
    couldn't install it.
    when i import, in my program, javax.comm.* it can't be resolve.
    thank for eny help..:-)

    Glad you got it to work. I would only say 2 very important things:
    1) Do not use an IDE as long as you can't code using notepad and command console and don't understand the concept "classpath". Now you've to learn both the IDE and the Java language basics. This is going to take a longer time than when you learn it one by one.
    2) You should NEVER place any 3rd party libraries in JRE/lib or JDK/bin. This is receipt for major future troubles. You should define the classpath yourself. You shouldn't misuse the default classpath.

  • How to display raw, not ascii, bytes from serial port?

    Hello, I have an instrument that outputs raw data, not ascii, bytes to a serial port.  How do you display raw data, not ascii, bytes from a serial port?  Since raw data bytes are not displayable, there is got to be something in labview to interpret/display the received bytes the way it is as data in HEX or Binary.  The STRING-TO-HEX and STRING-TO-BINARY functions are not applicable in this case because the bytes were not string type in the first place.  For example, if the receive byte is 0x4D, I need to display 4D in HEX or 77 in Decimal and not the ascii character "M" corresponding to 0x4D ascii code.  I am using a VISA-RD function currently to receive the data from a COM port.  VISA-RD outputs string type.  Thank for any feedback or suggestion in advance.

    BC@Baxter wrote:
    ...The STRING-TO-HEX and STRING-TO-BINARY functions are not applicable in this case because the bytes were not string type in the first place...
    Of course they are string type, just not formatted in a human readable form. So, YES, these functions are not appropriate.
    BC@Baxter wrote:
    For example, if the receive byte is 0x4D, I need to display 4D in HEX or 77 in Decimal and not the ascii character "M" corresponding to 0x4D ascii code. 
    Dennis is right, but there is no "decimal" display for strings, so the second requirement needs a tiny little bit more code.
    If you have a single byte string, you can typecast it into a U8 number and set the display format as decimal, hex, octal, or binary as desired. In decimal, it would display the number 77. Since it is now a numeric, you can even do math with it.
    In general, the string has multiple bytes, and you would typecast it into an array of U8 numbers (Since this is an often used function, there is also a "string to byte array" which does the same thing).
    Typecasting is the secret. You can e.g. easily typecast 2 bytes into a U16, 4 bytes into a I32, 8 bytes into a DBL,  etc. For more detailed requirements, there is also the "unflatten from string". Check the online help for details. Good luck!
    LabVIEW Champion . Do more with less code and in less time .

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