How to Read and Write Serial Port Data in Raspberry Pi

Hi,

I want Raspberry Pi to run a piece of code independently, read and write data from the serial port separately, and the other recipient is my PC. Can I directly deploy this code into it?I followed the Mathworks tutorial, but I don't know where the problem occurred. My current steps are as follows:

r = targetHardware('raspberry')
deploy(r,'tablelook')
function tablelook()%#codegen
r = raspi;
pc = serialdev(r,'/dev/serial0');
dataToSend = 1;
byteStream = typecast(dataToSend, 'uint16');
write(pc, byteStream);
output = read(pc,5,'uint16');
end

Raspberry Pi receives a 5 * 1 matrix from the PC and sends a 0/1 logic judgment to the PC.The code can run,but the data is incorrect,it's all zero.I dont know why it cannot work.

Many thanks,

Bang

[Walter Roberson]

dataToSend = 1;
byteStream = typecast(dataToSend, 'uint16');

byteStream

byteStream = 1×4

0 0 0 16368

That is a 1 x 4 array of uint16, not a 5 x 1 matrix of anything.

Note: when you use write() then no delimiter is sent. And if a delimiter were being sent you would have to worry about the fact that delimiters are typically one byte long, uint8, not uint16 like the other data you send.

[靖邦]

What I mean is that I want to put this code into Raspberry Pi and run it independently,My input is a 5 * 1 double precision matrix, which needs to be converted. I just gave an example here.When I send data from my PC, my serial communication assistant can detect data transmission, but the transmitted data is 0.

[靖邦]

I can change the data type to double,but my question is why the data I detected through my assistant is always zero?

(All my code is deployed to run in Raspberry Pi, not in Matlab)

function tablelook()%#codegen
r = raspi;
pc = serialdev(r,'/dev/serial0');
dataToSend = 1;
byteStream = typecast(dataToSend, 'double');
write(pc, byteStream);
output = read(pc,5,'double');

[Walter Roberson]

That code is expecting the other end of the serial port to be writing back something -- but you do not show us the code sending data to the raspberry.

[靖邦]

I know what your mean,here is my Complete process:

Firstly, I created a connection with Raspberry Pi in MATLAB and sent a matrix

r = raspi;
pc = serialdev(r,'/dev/serial0');
dataToSend = [22;4;5;6;7];
byteStream = typecast(dataToSend, 'double');

Then,I will deploy the following code to Raspberry Pi to read data from the serial port and send some data to the serial port

function tablelook()%#codegen
r = raspi;
rsp = serialdev(r,'/dev/serial0');
output = read(rsp,5,'double');
...%my system code
write(rsp,1,'double')

(I obtain my final 0/1 through the five input parameters and output it to the serial port)

Finally,I read the data in MALTAB

read(pc,1,'double')

But I get wrong data during transmission,all of them is zeros.

[Walter Roberson]

I recommend you set the baud rate when opening the serial ports.

[靖邦]

There is anthoer way to detect the raspberry pi's serial port is open?My baud rates same,and others is same too.Here is my raspberrry pi parameter and PC parameter:

[Walter Roberson]

https://raspberrypi.stackexchange.com/questions/26593/how-can-i-test-if-the-serial-uart-is-good-on-a-raspberry-pi might be of interest.