Issues receiving serial commands

mike2 · 2014-10-12 13:58

A lot of the code I've been finding online for sending and receiving data is using spin code.

I have a c project I'm working on in which I need to send and receive data to a python program over usb.

Here's my code. Does anyone know why it's not working?

#include <stdio.h>
#include <string.h>
#include <propeller.h>
#include <simpletools.h>


int main(void)
{
   // Wait some time
   waitcnt((CLKFREQ+CNT)*5);
   
   char buffer[300];
   int buflen = 300;
   
   serial *term;
   simpleterm_close();
   term = serial_open(31,30,0,57600);
   writeStr(term,"give_data\r");
   getStr(buffer, buflen);   
   waitcnt((CLKFREQ+CNT)*2);
   writeStr(term,"Data received.\r");  


  return 0;
}

Here's my python I run immediately after loading c code into ram using simpleide

import time
import serial


print "Communicating with propeller over COM4"


s = serial.Serial(
    port='COM4',\
    baudrate=57600,\
    parity=serial.PARITY_NONE,\
    stopbits=serial.STOPBITS_ONE,\
    bytesize=serial.EIGHTBITS,\
    timeout=0)


while True:
    data = s.read(9999)
    if len(data) > 0:
        print 'Received:'+ data
        if "give_data" in data:
            print "Sending data to the propeller..."
            s.write("Here is some data\r")
    time.sleep(1)
s.close()

Output

C:\Users\mike\Desktop>python scom.py
Communicating with propeller over COM4
Received:give_data
Sending data to the propeller...
_

kuroneko · 2014-10-12 16:36

FWIW, I can't see how getStr would be connected to term. I'd have used readStr instead.

mike2 · 2014-10-12 19:08

Using readstr I get garbled data back...

readStr(term, buffer, buflen);

C:\Users\mike\Desktop\>python scom.py
Communicating with propeller over COM4
Received:give_data
Sending data to the propeller...
Received:H½ii&#9570;ët°

If I use the parallax serial terminal I can use C read functions like scanf, but I need to get python working.

Same result running this on a linux host

ubuntu@ubuntu:~$ sudo python scom.py
Communicating with propeller over /dev/ttyUSB0
Received:give_data
Sending data to the propeller...
Received:H&#65533;ii&#65533;&#65533;t

kuroneko · 2014-10-12 20:04

Just ran the following program, and after I send some response from the terminal I get the Data received message.

#include <stdio.h>
#include <string.h>
#include <propeller.h>
#include <simpletools.h>


int main(void) {
    // Wait some time
    waitcnt(CLKFREQ*3 + CNT);
   
    char buffer[300];
    int buflen = 300;
   
    serial *term;
    simpleterm_close();
    term = serial_open(31, 30, 0, 115200);
    writeStr(term, "give_data\r");
    readStr(term, buffer, buflen);   
    waitcnt(CLKFREQ*2 + CNT);
    writeStr(term, "Data received [");
    writeStr(term, buffer);
    writeStr(term, "]\r");

    return 0;
}

terminal output:

give_data
[COLOR="#FF8C00"]user data from terminal[/COLOR]
Data received [user data from terminal]

Your delays look slightly off but shouldn't have an effect on the transfer as such. You could try a simple loopback first where the prop simply echos the incoming data.

mike2 · 2014-10-12 20:28

I changed to use fdserial instead of serial and the problem resolved. I think it might be an issue with python.

#include <stdio.h>
#include <string.h>
#include <propeller.h>
#include <simpletools.h>
#include <simpletext.h>
#include "fdserial.h"


int main(void)
{
   // Wait some time
   pause(3000);
   
   char buffer[300];
   int buflen = 300;
   
   serial *term;
   simpleterm_close();
   term = fdserial_open(31,30,0,57600);
   writeStr(term,"give_data\r");
   readStr(term,buffer, buflen);   
   writeStr(term,"Data received.\r"); 


  return 0;
}

C:\Users\mike\Desktop>python scom.py
Communicating with propeller over COM4
Received:give_data
Sending data to the propeller...
Received:Here is some data
Data received.

kuroneko · 2014-10-12 21:21

Just wondering, as serial is running unbuffered can you increase the number of stopbits on the host side and see if it makes a difference. If it's still too fast at least I'd expect slightly different garbage.

mike2 · 2014-10-12 22:10

Your prediction is right on that. If you change the stop bit it changes the garbage that gets spewed back.

[code]
C:\Users\mike\Desktop>python kuronekotest.py
Communicating with propeller over COM4
Received:give_data
Sending data to the propeller...
Received:Hn,

Issues receiving serial commands

Comments