No instance of overload function

[Will Blight]

I am using the MTSSerial library and I get the following 2 errors when I try to use write(const char* data, int length) or read(const char* data, int length).

Error Messages
Error: No instance of overloaded function “mts::MTSSerial::write” matches the argument list in “main.cpp”, Line: 54, Col: 9
const char* data, int length
Error: No instance of overloaded function “mts::MTSSerial::read” matches the argument list in “main.cpp”, Line: 22, Col: 17

Library code

  /** This method enables bulk writes to the Tx or write buffer. This method
    * blocks until all the bytes are written.
    *
    * @param data the byte array to be written.
    * @param length the length of data to be written from the data parameter.
    * @returns the number of bytes written to the buffer, which should be
    * equal to the length parameter since this method blocks.
    */
    int write(const char* data, int length);

My code

#include "mbed.h"
#include <iostream>
#include "MTSSerial.h"
#include "stm32f4xx.h"

DigitalOut bc_nce(PB_2);
 
int main() {
    unsigned char Send_Buffer[160];
    int i;
    bc_nce = 1;
    mts::MTSSerial sp(D1,D0);
    sp.baud(1200);
    
    for (i=0; i< 10; i++)
       Send_Buffer[i] = 0xFF;
       
    wait(1);

    int bytes = 10;
    sp.write(Send_Buffer,bytes);
    bytes = sp.read(Send_Buffer,160);
    while (1)
    {
    }

}

• This topic was modified 7 years, 11 months ago by Will Blight.

[Mike Fiore]

Will,

The prototypes are actually as follows

    /** This method enables bulk writes to the Tx or write buffer. This method
    * blocks until all the bytes are written.
    *
    * @param data the byte array to be written.
    * @param length the length of data to be written from the data parameter.
    * @returns the number of bytes written to the buffer, which should be
    * equal to the length parameter since this method blocks.
    */
    int write(const char* data, int length);

    /** This method enables bulk reads from the Rx or read buffer. This method
    * blocks until the amount of data requested is received.
    *
    * @param data the buffer where data read will be added to.
    * @param length the amount of data in bytes to be read into the buffer.
    * @returns the total number of bytes that were read. This should be equal
    * to the length parameter since this is a blocking call.
    */
    int read(char* data, int length);

I believe the issue is that your buffer is of type unsigned char[], while the write and read functions accept types const signed char[] and signed char[] respectively. Try casting to those types like this

sp.write((const char*)Send_Buffer, bytes);
bytes = sp.read((char*)Send_Buffer, 160);

Cheers,

Mike

[Will Blight]

Hi Mike,
Your are correct. Can’t believe I made such a dumb mistake. I thought I had already changed the types. I am sure 4 hours sleep had nothing to do with it. Someone put more coffee on!

Will.

[Author]

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