Arduino-serial: updated!

15 Replies to “Arduino-serial: updated!”

1. It was, in fact, cockpit error:
   arduino-serial -b 9600 -p /dev/cu.usbmodem1421 -S 'V' -t 10000 -e '\r' -r
   does not set the end char to [return], but rather to backslash. The right way to quote it in bash is:
   arduino-serial -b 9600 -p /dev/cu.usbmodem1421 -S 'V' -t 10000 -e $'\r' -r

2. serialport_read_until() method needs some optimization, in particular these 2 fixes!

   1) More proper way to declare char:

   char b[1]; change to char b;
int n = read(fd, b, 1); change to int n = read(fd, &b, 1);
buf[i] = b[0]; change to buf[i] = b;
while( b[0] != until ... change to while( b != until ...

   2) Overflow problem

   while( ... && i < buf_max ... change to while( ... && i+1 < buf_max ...

   Unless the documentation says that buf_max should be one less than the size of the buffer (which would be counterintuitive and error-prone)

   Also, since i is checked at the end, even with this fix, the code will still store one byte if you pass in buf_max == 0 (but without the fix it will store two bytes). So that’s another bug.

   https://github.com/todbot/arduino-serial/issues/10

3. Hi Tasya,
   You are probably running into a common issue we all have to deal with: opening up the serial port on the computer side of things causes the Arduino to reset and wait in the Arduino bootloader for a bit.

   To guard against this, you’ll see computer-side code often have the following flow:
   1. Open serial port
   2. Wait some amount of time (2 seconds is common)
   3. Write to serial port (or read, depending on your situation)
   4. Keep doing 3 until you no longer want to talk to the Arduino
   5. Close serial port

   To do something like this with “arduino-serial” commandline tool , you would do:

    ./arduino-serial -b 9600 -p /dev/ttyACM0 -d 2000 -s "a"
   

   This will open /dev/ttyACM0 at 9600 bps, wait 2 seconds, then send “a”, then close /dev/ttyACM0. But then if you run “arduino-serial” again, it re-opens the serial port, thus causing the Arduino to reset.

4. Hi! Todbot! I changed my code to send numbers and the case to numbers instead and it worked. The thing is, I need to run “arduino-serial” on the command line first everytime I change the Arduino code before I run the C program for it to work. Do you have any idea of what’s causing this?

5. Hi Todbot! Thank you for the great library. However, I have a problem. When using arduino-serial from the terminal I can send message just fine to the arduino. When using a C program, however, the message seems to not reach the arduino although no error were shown.

   The following is my C code:

   #include "arduino-serial-lib.c"
   #include "arduino-serial-lib.h"
   
   main(void)
   {
       const char* mes = "a";
       int dev = serialport_init("/dev/ttyACM0", 9600);
       serialport_write(dev, mes);
   }
   
   

   and my arduino code is:

   int incomingByte;
   char button;
   
   void setup() {
     // put your setup code here, to run once:
     pinMode(13, OUTPUT);
     Serial.begin(9600);
   }
   
   void loop() {
     // put your main code here, to run repeatedly:
     if (Serial.available() > 0) {
       // read the incoming byte:
       incomingByte = Serial.read();
       Serial.print(incomingByte;
   
       switch(incomingByte) {
         case "a":
           digitalWrite(13, HIGH);
           break;
         case "b":
           digitalWrite(13, LOW);
           break;
       }
     }
   }
   

   Do you know what might be the problem?

   Thanks!

   tasya

6. Thanks, this code was really useful. The only issue I had was that sometimes the string read from the arduino would contain backspaces that would delete the first part of the string. I’m not sure why that happened because my arduino sketch definitely didn’t include them. It was simple to fix by inserting the strip() function from here:

   http://rosettacode.org/wiki/Strip_control_codes_and_extended_characters_from_a_string#C

7. Hi Eva,

   You can just include `arduino-serial-lib.h` and `arduino-serial-lib.c` in your C project and then do something like:

   char str_to_send[] = "Up";
   int dev = serialport_init("/dev/ttyUSB0", 9600);
   serialport_write(dev, send_str, strlen(send_str) );
   

8. Hello Tod,

   i’m actually trying to use your code because I would like to send some string to my Arduino.
   But I do not want to do it from the linux terminal, I have a long code that uses several parameters to determine the direction of the strip leds connected to the Arduino.

   I just want the code to be able to take a printf(“Up”) that comes from the previous code and send Up to the Arduino.
   I do not need any getopt, so I do not know how to change the case ‘s’ and the serialport_write

   Thank you very much

9. Thanks, this solved my problem perfectly. I have a number of arduino-controlled projects for the care and entertainment of my cats. They suddenly stopped working. (I using echo to write to the serial port.) With your program, everything works again.

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11. Hello,

    I am very new to all of this but I got an arduino starter kit and I am trying to use voice recognition with it. I have downloaded the files: arduino-serial.c, arduino-serial0lib.c, and arduino-serial.lib.h and put them on the root of my system. I also downloaded Xcode for my computer and enabled the command line tools.

    I am now trying to compile arduino-serial so I can communicate with my little toy and I get a bunch of warnings and 2 errors that prevent me from using arduino-serial.

    Here I copy what my terminal tells me. Any idea what I am doing wrong? Thank you very much,
    Bene

    error: expected identifier or ‘(‘
    {\rtf1\ansi\ansicpg1252\cocoartf1187\cocoasubrtf400
    ^
    ./arduino-serial-lib.h:55:2: warning: missing terminating ‘ character
    [-Winvalid-pp-token]
    \’a0\’a0
    ^
    ./arduino-serial-lib.h:64:2: warning: missing terminating ‘ character
    [-Winvalid-pp-token]
    \’a0\’a0
    ^
    ./arduino-serial-lib.h:71:2: warning: missing terminating ‘ character
    [-Winvalid-pp-token]
    \’a0\’a0
    ^
    ./arduino-serial-lib.h:80:2: warning: missing terminating ‘ character
    [-Winvalid-pp-token]
    \’a0\’a0
    ^
    ./arduino-serial-lib.h:91:2: warning: missing terminating ‘ character
    [-Winvalid-pp-token]
    \’a0\’a0
    ^
    ./arduino-serial-lib.h:106:2: warning: missing terminating ‘ character
    [-Winvalid-pp-token]
    \’a0\’a0
    ^
    arduino-serial.c:156:21: warning: implicit declaration of function
    ‘serialport_close’ is invalid in C99 [-Wimplicit-function-declaration]
    serialport_close(fd);
    ^
    arduino-serial.c:160:22: warning: implicit declaration of function
    ‘serialport_init’ is invalid in C99 [-Wimplicit-function-declaration]
    fd = serialport_init(optarg, baudrate);
    ^
    arduino-serial.c:163:17: warning: implicit declaration of function
    ‘serialport_flush’ is invalid in C99 [-Wimplicit-function-declaration]
    serialport_flush(fd);
    ^
    arduino-serial.c:168:22: warning: implicit declaration of function
    ‘serialport_writebyte’ is invalid in C99 [-Wimplicit-function-declaration]
    rc = serialport_writebyte(fd, (uint8_t)n);
    ^
    arduino-serial.c:168:48: error: use of undeclared identifier ‘uint8_t’
    rc = serialport_writebyte(fd, (uint8_t)n);
    ^
    arduino-serial.c:177:22: warning: implicit declaration of function
    ‘serialport_write’ is invalid in C99 [-Wimplicit-function-declaration]
    rc = serialport_write(fd, buf);
    ^
    arduino-serial.c:183:17: warning: implicit declaration of function
    ‘serialport_read_until’ is invalid in C99
    [-Wimplicit-function-declaration]
    serialport_read_until(fd, buf, eolchar, buf_max, timeout);
    ^

12. Thanks, i use it for my meterN project
    cheers

13. Hi Goatboy,
    Yeah the reason why it’s commented out was because it can’t work. On Mac OS X & Linux (I think), the act of opening the port toggles DTR, regardless of the settings.

14. I’ve poked around your code a bit and I was wondering if you’d be able to either make the change or discuss with me how to deal with the DTR/HUPCL “auto-reset Arduino every damn time you wanna use serial” issue. I love your code, it’s very simple and clean, does what it needs to. I just couldn’t get the commented-out

    Line 39: ioctl(fd, TIOCMBIC, &iflags); // turn off DTR

    to work in arduino-serial-lib.c. I also uncommented the

    Line 37: int iflags = TIOCM_DTR;

    line above it.

    Any help would be greatly appreciated as I am banging my head over trying to get serial to work without resetting the Arduino.

    Much thanks!

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