SD library and UDP Client (problem sending data)

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 :)

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

 myFile ="tiger.bmp");
    if (myFile) {
     while( myFile.available()) {
       byte myByte;
       myByte =;
       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?


       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?

... and sending a single byte ...

Do mean:

       udpClient.writeDatagram(myByte, 1);

Can you post the whole thing? Save us looking up all the “blah blah blah” stuff (libraries, declarations etc.)

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

I'm essentially modifying the UDPEchoServer example (,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. will read the any file byte at a time.

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

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

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