PhpSerial: No stty available — cant seem to get it

问题:

I'm working on a project which involves reading and writing to a Serial board, using the UART pins on my Raspberry Pi. However, I have hit a brick wall already. Any time I try use PhpSerial I always get the error:

Fatal error: No stty available, unable to run. in /var/www/PHP-Serial/examples/PhpSerial.php on line 56

I've tried numerous configurations with the input:

// First we must specify the device. This works on both linux and windows (if
// your linux serial device is /dev/ttyS0 for COM1, etc)
$serial->deviceSet("/dev/ttyAMA0");

// We can change the baud rate, parity, length, stop bits, flow control
$serial->confBaudRate(38400);
$serial->confParity("none");
$serial->confCharacterLength(8);
$serial->confStopBits(1);
$serial->confFlowControl("none");

php/lighthttpd is running as www-data, Ive tried chowning the /dev/ttyAMA0 to that user, and I've added the dialout group to said user. I cant see any disable functions or anything in my php.ini. I've also don't the standard setup for using serial devices on the pi as per the wiki, and I am able to read/write data to and from the circuit using

sudo minicom -b 38400 -o -D /dev/ttyAMA0

Here are the line(s) that the error is referring to:

    if (substr($sysName, 0, 5) === "Linux") {
        $this->_os = "linux";

        if ($this->_exec("stty") === 0) {
            register_shutdown_function(array($this, "deviceClose"));
        } else {
            trigger_error(
                "No stty available, unable to run.",
                E_USER_ERROR
            );
        }

I can't make sense of it but someone else might. Thanks in advance.

回答1:

The solution to your problem is as follows:

You have to change the following line of code in the PhpSerial.php class

FROM:

if ($this->_exec("stty") === 0) {

TO:

if ($this->_exec("stty --version") === 0) {

=> This consequently resolves the "No stty available, unable to run..." error. See this thread: https://www.raspberrypi.org/forums/viewtopic.php?f=91&t=100481

I should also add that I've had to place a delay before I write serial data out e.g.

<?php

error_reporting(E_ALL); ini_set('display_errors', '1');

include "PhpSerial.php";//serial class: https://github.com/Xowap/PHP-Serial/blob/develop/examples/VS421CPNTA.php

$serial = new phpSerial;
//$serial->deviceSet("/dev/ttyAMA0");
$serial->deviceSet("/dev/ttyACM0");

$serial->confBaudRate(9600);
$serial->confParity("none");
$serial->confCharacterLength(8);
$serial->confStopBits(1);
$serial->deviceOpen();

sleep(3);//delay
$serial->sendMessage("1");

$serial->deviceClose();
echo "Serial message sent! \n";

回答2:

As you can see PhpSerial needs stty utility to get/set serial parameters like baudrate, parity etc. The solution is to install stty by the means of your Linux distribution

回答3:

STTY on Rasbian returns a 1 on the exec, rather than 0

Unfortunately if you just bypass this code, it hangs on register_shutdown_function.

Currently I am writing files to disk, and trying to send them to the port (struggling because they are binary text rather than ascii). If you have ascii info to send, then

    stty -F /dev/ttyAMA0 38400

And

    exec("cat filename.txt > //dev//ttyAMA0");