STM32 USB buffer not retrieved correctly

Question

im pretty new on the STM32 and i encountered a problem.

With a Qt App i'm sending stuff over the USB with the following code:

if (m_hidDevice->isOpen())
{
    QByteArray buffer(m_hidDevice->readOutputBufferSize(), 0);

    buffer[0] = 16;
    buffer[1] = 18;

    uint16_t number = 4096;
    uint16_t randomValue = qrand() % number;

    buffer[2] = (char)((randomValue >> 8) & 0x00ff);
    buffer[3] = (char)(randomValue & 0x00ff);

    buffer[4] = (char)((2556 >> 8) & 0x00ff);
    buffer[5] = (char)(2556 & 0x00ff);

    qDebug() << "------------" << randomValue;
    qDebug() << "//" << (uint8_t)buffer[2] << "//" << (uint8_t)buffer[3];
    qDebug() << "//" << (uint8_t)buffer[4] << "//" << (uint8_t)buffer[5];

    m_hidDevice->write(buffer);

and on the STM32F4 im using

switch (buffer[1])
    {
        case 18:                
            x = ((uint16_t)buffer[2] << 8) + buffer[3];
            y = ((uint16_t)buffer[4] << 8) + buffer[5];

            sr.m_value1[0] = x;
            sr.m_value1[1] = y;

            do(M);

m_value has size 4 and it is uint16_t;

The output on the Qt App is

------------ 2083
// 8 // 35
// 9 // 252

while on the STM32F4 x and y have values

x = 2083 (as expected)
y = 0

Now the size of the buffer should be 64 bytes while my data is 8*5 = 40 bytes. My question then is why i can't retrieve correctly the values in the buffer?

Regards,

Answer 1

0x09, 0x01,       // USAGE (Vendor Usage x) --> x = 1,2,3
0x75, 0x08,       // REPORT_SIZE (8) --> 2^8 = 255
0x15, 0x00,       // LOGICAL_MINIMUM (0)
0x26, 0xff, 0x00, // LOGICAL_MAXIMUM (255) 
0x85, 0x02,       // REPORT_ID (n)          --> n must be the report id 
0x95, 0x3f,       // REPORT_COUNT (63)      --> size
0x91, 0x02        // OUTPUT (Data,Var,Abs)