[SOLVED]Byte processing , serial communication

hello,

i'm working on gui project arduino , want send 7 bytes arduino. array should 16115061 16 sop , 61 eop. 1 parameter type(1 speed,2 proportional value, etc.) , 150 pwm value.

for example if wanted speed of motor 150(pwm) packet lool 16115061, if wanted  to send value of 10,54 proportional value packet should 16210,5461.

i made numericupdown control should ,by pressing enter, send packet arduino

code: [select]

private void numericsetpoint_keypress(object sender, keypresseventargs e)
        {
            if (e.keychar == 13)
            {
                if (serialport1.isopen)
                {
                    byte[] send = new byte[7];
                    float setpoint = (float)numericsetpoint.value;
                    byte[] x = bitconverter.getbytes(setpoint);
                    send[0] = convert.tobyte(16);
                    send[1] = convert.tobyte(1);
                    send[2] = x[0];
                    send[3] = x[1];
                    send[4] = x[2];
                    send[5] = x[3];
                    send[6] = convert.tobyte(61);
                    //array.reverse(x);
                    serialport1.write(send, 0, 1);
                    printbytearray(send);
                }

printbytearray() helper function shows array in console. if enter 40 prints new byte[] { 16, 1, 0, 0, 72, 66, 61, }, 255 prints new byte[] { 16, 1, 0, 0, 127, 67, 61, }.

the receiving part on arduino looks,so far, this:

code: [select]


int motorpin = 9;
byte bytearray[7];
float speed;

union
{
  byte b[4];
  float kfloat;
}p;

void setup()
{
  serial.begin(9600);
}

void loop()
{
  if(serial.available() == 7)
  {
  for(int = 0; i<7; i++)
  {
    bytearray[i] = serial.read();
  }
  }
  //convert float
  p.b[0] = bytearray[2];
  p.b[1] = bytearray[3];
  p.b[2] = bytearray[4];
  p.b[3] = bytearray[5];
  
  speed = p.kfloat;
 
  analogwrite(motorpin,speed);
  
    
}

the problem don't know how convert 4 bytes float , pass them analogwrite. motor doesn't start. how should proceed ? doing wrong ?

the second parameter in analogwrite byte not float.

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