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works fine until i try to write the incomming data to the sd card.
while (watchdog.ElapsedMilliseconds <= timeout && bytesWritten < size60)
{
fs.Write(serialBuffer, 0, bufferLength); //write received bytes to sd
bytesWritten += bufferLength;
Debug.Print("written: " + bytesWritten);
bufferLength = 0;
}
fs.Close();
I'm receiving a picture from a camera.
if i lose the line
fs.Write(serialBuffer, 0, bufferLength);
I receive all the bytes of the picture.
When i write the bytes from buffer to SD, i lose some bytes.
I guess the write routine takes to long, and therefore the incoming serial-data can't be written to the buffer.
How can i buffer the incoming data without any loss?
I see only snapshots of your code, I don't see where "fs" is set. Could it be that it gets destroyed by the garbage collector?
I can write without any problems to the sd card and there are no errors.
I just can't receive all the bytes from the serial, while trying to write them to the sd card.
In the time i write to the sd card, a new set of data would be received. but since i'm still writing to the sd card, the incoming serial data is dismissed.
What speed are you using for your serial connection?
If you use software flow control, are you able to capture all the data?
Chris
I'm on 115200 kbps/baud.
unfortunately the camera doesn't support any flow control at all. As soon as i request an image the camera starts sending one whole frame.
Whats weird is, that the serial-buffer(512bytes on the netduino) doesn't even fill up.
I wait till the bytes in the serial-buffer are > 0 and then immediately write to the SD card. So i write about 40 bytes each time. when i check the serial-Buffer again there are another 20ish bytes to write.
Still, at the end i'm losing data. As soon as I don't write to the SD-Card, every byte will be received.
I tried lowering the baudrate. still the same problem.
Does the interrupt-Routine (Event Handler) of the serial, interrupt the filestream to the sd card?
public class Program
{
//static SerialPortHelper serial1;
static SerialPort serial1;
static SerialPort serial2;
static ThermalPrinter printer;
static Ucamttl camera;
static FileStream fs = File.Create("\\SD\\picture.raw");
public static void Main()
{
Is there a reason Program isn't declared Static, while all methods and properties inside are static?
Also, you're overwriting the first values all the time, in Ucamttl.cs:
public class Ucamttl
{
static SerialPort serial;
static UInt16 _packageSize;
static int bufferLength = 0;
const int bufferMax = 513;
static byte[] serialBuffer = new byte[bufferMax];
static byte[] _command = new byte[Constants.CMD_SIZE];
static Stopwatch watchdog = new Stopwatch();
public Ucamttl(SerialPort sp)
{
serial = sp;
serial.DataReceived += new SerialDataReceivedEventHandler(camera_DataReceived);
watchdog.Start();
}
static void camera_DataReceived(object sender, SerialDataReceivedEventArgs e)
{
int bytesReceived = serial.BytesToRead;
if (bytesReceived > 0)
{
serial.Read(serialBuffer, 0, bytesReceived);
bufferLength += bytesReceived;
}
}
I think you want to append to the buffer, not overwrite it all the time.
I'm not sure which camera you're using? I know here is some code for Adafruits TTL camera, maybe that's helping?
Is there a reason Program isn't declared Static, while all methods and properties inside are static?
No reason...
I think you want to append to the buffer, not overwrite it all the time.
Did that.
this allowed me to save a smaller picture of 19200 bytes directly to the netduino.
and write it to the SD, after the picture was fully transferred.
Since I can't allocate 76800 bytes for a 320x240 picture I would need to Thread the SD-write process somehow, without interrupting the eventhandler from the serial...
Maybe you should change that, this could cause an issue with the garbage collector, although I'm not sure. Best to keep your code consistent though.
Did that.
this allowed me to save a smaller picture of 19200 bytes directly to the netduino.
and write it to the SD, after the picture was fully transferred.
No you didn't
Your buffer doesn't sync right, that's the main issue I think.
public bool GetPicture(UInt32 pictureSize, FileStream fs)
Your buffer doesn't sync right, that's the main issue I think.
how can i check?!!!
i tried waiting until the serialbuffer on the netduino 512byte is filled up and write to the SD card while it's filling up. but most of the time there were only ~32bytes in the buffer then it stopped.
only after reading the serial, the serialbuffer from the serial filled again up to about 32bytes.
like i said
I would need to Thread the SD-write process somehow, without interrupting the eventhandler from the serial...
You've been a great help so far helping me comprehend what's going on. Thanks a lot!
I would move the code that writes the file to the camera_DataReceived method too. Or at least call the writing of the file in that method. That way you'll keep code execution a bit more under control.
I would move the code that writes the file to the camera_DataReceived method too. Or at least call the writing of the file in that method. That way you'll keep code execution a bit more under control.
I will do that, and post any helpful results here. Maybe its of any use someday...
I'm glad to.
