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Topic: SD library and UDP Client (problem sending data) (Read 805 times) previous topic - next topic

designer

sorry if this is a noob problem, I'm a circuit designer by profession and programming is not my forte.

I have a Chipkit max32 set up with a wifi shield and sd card. I'm using SD.h library and trying to open a file and sending a single byte using UDP client.

Yes, I know this probably not a very efficient way of sending data, but we'll get to that later :)
Code: [Select]

//blah blah blah...initialize card, initialize UDP,
//no problems here, have used it many times
//
//

myFile = SD.open("tiger.bmp");
    if (myFile) {
     while( myFile.available()) {
       byte myByte;
       myByte = myFile.read();
       udpClient.writeDatagram(myByte, myFile.size());
     }
    }

//blah blah



my problem is the writeDatagram function does not like taking myByte:
WiFiUDPEchoServerSDTest.cpp: In function 'void loop()':
WiFiUDPEchoServerSDTest.cpp:459:50: error: invalid conversion from 'byte' to 'const byte*'
WiFiUDPEchoServerSDTest.cpp:459:50: error:   initializing argument 1 of 'long int UdpClient::writeDatagram(const byte*, size_t)'

I don't understand the conversion problem here, help?

Thanks,

Nick Gammon

Code: [Select]

       udpClient.writeDatagram(myByte, myFile.size());


I don't understand what you are attempting here. You want to write one byte for the length of the entire file?
Please post technical questions on the forum, not by personal message. Thanks!

More info:
http://www.gammon.com.au/electronics

Nick Gammon

Quote
... and sending a single byte ...


Do mean:

Code: [Select]

       udpClient.writeDatagram(myByte, 1);

Please post technical questions on the forum, not by personal message. Thanks!

More info:
http://www.gammon.com.au/electronics

Nick Gammon

Can you post the whole thing? Save us looking up all the "blah blah blah" stuff (libraries, declarations etc.)
Please post technical questions on the forum, not by personal message. Thanks!

More info:
http://www.gammon.com.au/electronics

designer


Thanks for your reply, I really appreciate it.The code is very long.

I'm essentially modifying the UDPEchoServer example (http://digilentinc.com/Products/Detail.cfm?NavPath=2,401,884&Prod=PMOD-WIFI  -> UDPEchoServer.pde) where during the WRITE case, I want to read a bitmap image file from the SD card and send it across the server. An Iphone is receiving the image. I've been playing around with how to send a bitmap file and trying to send a stream of bytes and redraw with Xcode.

You are correct, the length should be 1, it is only one byte.

myFile.read() will read the any file byte at a time.

PaulS

Quote
I have a Chipkit max32 set up with a wifi shield and sd card.

I'm sorry. Did you have an Arduino question?

designer

The libraries are essentially identical, and the arduino forum has provided me much more resources so I thought I would ask here. Thanks

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