Hello Christoph
Am Samstag, den 24.09.2016, 17:46 +0200 schrieb Christoph M. Becker:
> On 24.09.2016 at 16:29, Torsten Rosenberger wrote:
>
> > i try to write a php extension for raspberry to get i2c data.
> > This is my first extension. And maybe not the corect mailing list.
> >
> > The Problem, on the CLI I get the correct return value.
> > If i run the same code in an webbrowser i got a wrong value.
> >
> > PHP_FUNCTION(i2c_read_value)
> > {
> > int arg_len;
> > unsigned char reg;
> > unsigned short res;
> >
> > if(zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "s", ®,
> > &arg_len) == FAILURE){
>
> That looks wrong. `reg` should be declared as `char *`.
i have seen “s”: string, expects char* and int.
but reg should be int it is a hex number for the i2c bus.
>
> > RETURN_FALSE;
> > }
> >
> > res = i2c_smbus_read_byte_data(dev_fd, reg);
>
> Where is dev_fd defined and initialized?
at the top of the extension script
int dev_fd;
>
> > RETURN_LONG(res);
> > }
> >
> >
> > if i run these code in CLI
> > <?php
> >
> > i2c_init(1,0x48,0);
> > echo i2c_read_value(0x40);
> > i2c_close();
> >
> > ?>
> >
> > php i2c.php
> >
> > i get 49 these comes from an ADC and the range is 0 - 255. In an C
> > programm i get the same value.
> >
> > wenn I run the script in an browser i get: 65535
> >
> > someone can give me a hint ?
>
> There might be a permission or working directory issue.
you are right! apache2 was not able to access /dev/i2c-1 so I add the
apache2 user to the i2c group but also had to change the acces mod to
the file.
now it works
Thanks's a lot!
BR/Torsten
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