Unable to send and receive images between 2 Raspberry connected to Zigbee via UART.

[J.Hilk]

@mrjj IIRC, it's passed on to the OS during the write call and that copies the data. But I'm not entirely sure 😬

[mrjj]

@J-Hilk
Yeah i was wondering since its a board if that still happens as it would
make sense we get cut if not.

@Rika
Can you try this

void serial::on_pushButton_2_clicked()
{
        static QByteArray ba;
        ba.fill('A', 1000);
        if(serialPort->isOpen()==true){
            serialPort->write(ba);
            qDebug()<<ba.size()<<"size_send:";
        }
}

and tell me if we still only get up to 190 bytes with the sizeeeee message.

[Rika]

@mrjj I tried, still only get 190.
16 sizeeeee:
32 sizeeeee:
64 sizeeeee:
64 sizeeeee:
14 sizeeeee:

[mrjj]

@Rika
Good testing.
So even it says
qDebug()<<ba.size()<<"size_send:";
1000 size_send
you only get
5 lines of
16 sizeeeee:
32 sizeeeee:
64 sizeeeee:
64 sizeeeee:
14 sizeeeee:
?

[Rika]

@mrjj Sometimes 4 lines, sometimes 7 lines, but the total is 190 bytes. With 500-A, received only 230

[mrjj]

@Rika
Ok
if we do
ba.fill('A', 10);
do you then get all ?

[Rika]

@mrjj yes.

[mrjj]

@Rika
So it seems data get cut over some size.

What Os is running on the boards ?

Also maybe Zigbee has some sort of max transfer size ?

[Rika]

@mrjj I use raspbian. I tried using a PC connected to zigbee and sent photos to my Pi4 + Zigbee with Realterm, my Pi4 received the photos. I think the error is in the program sends the data.

[J.Hilk]

well, lets narrow it down,
write returns a quint64 with the actual number of bytes written to the serialport, what does that return ?

void serial::on_pushButton_2_clicked()
{
        static QByteArray ba;
        ba.fill('A', 1000);
        if(serialPort->isOpen()==true){
            quint64 send = serialPort->write(ba);
            qDebug()<<send << " of" << ba.size()<<"size_send:";
        }
}

[Rika]

@J-Hilk 1000 of 1000 size.

[J.Hilk]

@Rika well,
to make sure your 2nd application is not simply very late in its creation/startup process, try clicking the button a 2nd time, see if something changes :D

After that, time for a serial port listing device, to check what is actually transferred

[mrjj]

@J-Hilk
When i goggle Zigbee , i do see max payload mentioned.
Do you think that could be the cause here ?
I never used Zigbee so not sure if its even an issue.

[J.Hilk]

@mrjj uh, I should read the opening post more clearly,

You're right, that is most likely the issue, ZigBee is a low data transfer protocol and from what my quick google search told me, limited to about 100 - 200 bytes, which fits exactly here

for a quick and dirty test, we could split the test byte array and send it delayed, that should work

void serial::on_pushButton_2_clicked()
{
        static QByteArray ba;
           int index(0);
           ba.fill('A', 1000);
           if(serialPort->isOpen()==true){
               QTimer *t = new QTimer();
               auto sendSection = [=,&index]()->void{
                   serialPort->write(ba.data() + index * 100, 100);
                   index ++;
                   if(index == 10)
                       t->deleteLater();
               };
               QObject::connect(t, &QTimer::timeout, sendSection);
               t->start(1000);
        //       quint64 send = serialPort->write(ba);
               qDebug()<< ba.size()<<"size_send:";
           }
}

[Rika]

@mrjj @J-Hilk Sorry for my late reply. The problem is when I try to send from PC with Realterm (Pc is also connected to Zigbee), on Pi4 I still get pictures.