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Thread: LPT thermometer

  1. #1

    Question LPT thermometer

    Hello,

    I'd like to connect some I2C thermometer chip to parallel port of WL500g, but so far I've no idea about low-level control of specific LPT pins in WL500g. Is there some example code to toggle and read ASUS parallel port pins?

  2. #2
    I am looking for this for about two weeks with no answer (how to control the LPT of that f***ing thing).
    No answers yet.

  3. #3
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    Just use generic parallel port ioctls, that's it. But remember to remove lp.o module first.

  4. #4
    Quote Originally Posted by Oleg
    Just use generic parallel port ioctls, that's it. But remember to remove lp.o module first.
    Oleg, would You (or somebody else) please compile _simple_ LPT ioctl binary program, that can be called with additional parameters from command line?

    Something like:
    lptioctl port_no bit_no value

    and:
    lptioctl port_no bit_no
    (where return value = bit state)

    Then it will be quite easy (at least for me) to write simple shell script for I2C or anything else.

  5. #5
    Yes, that would be more than helpful. I would like to see the source also.
    My idea about that is something like this
    ./lptioctl (portnumber) send (number)
    ./lptioctl (portnumber) read
    => returns a byte

  6. #6
    this is where i got:

    [quote]
    #include <linux/config.h>
    #include <linux/module.h>
    #include <linux/init.h>
    #include <linux/ioport.h>
    #include <linux/kernel.h>
    #include <linux/slab.h>

    #define base 0xBF800010

    static void parport_write_data(unsigned char d) {
    unsigned char *io = (unsigned char *) base;
    *io = d;
    }

    static unsigned char parport_read_data() {
    unsigned char *io = (unsigned char *) base;
    return *io;
    }

    static unsigned char parport_read_status()
    {
    unsigned char *io = (unsigned char *) base;
    return *(io+1);
    }
    static int LPTInit()
    {
    check_mem_region(base, 3)
    }

    static void parport_splink_unregister_port()
    {
    release_mem_region(base, 3);
    }

    int main()
    {
    if (LPTInit())
    {
    int i;
    for (i=0;i<10000;i++) {
    parport_write_data(254);
    usleep(10000);
    parport_write_data(1);
    usleep(10000);
    }
    }
    }
    [quote]

    i'm compiling it with
    mipsel-uclibc-gcc -o p.c
    This thing should blink some data pins on the lpt port, right? But it doesn't. It just gives me a nice Segmentation Fault.
    I removed all the lpt stuff from the firmware (modules, lpd and l910...) (in fact it's a 10gig hdd partition)

    What i've done wrong?

  7. #7
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    Use iopl(3) to get an access.
    In fact you will probably need to mmap this memory first to get an access to it.

  8. #8
    please give me an example.

  9. #9
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    Check this code for the general mmap code sample:

    http://wl500g.info/attachment.php?attachmentid=171

    Most likely you will need to change 0xBF800010 to 0x1F800010; mmap 0x1F800000 (aligned), then access +0x10.

  10. #10
    lost myself there

  11. #11
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    Code:
    	void *map;
    	unsigned char *base;
    
    	int fd = open("/dev/mem", O_RDWR);
    
    	if (fd < 0) {
    		perror("/dev/mem");
    		return 1;
    	}
        
    	map = mmap(NULL, 0x1000, PROT_READ | PROT_WRITE, 
    		MAP_SHARED, fd, 0x1f800000);
    	
    	if (map == NULL) {
    	    perror("mmap");
    	    return 1;
    	}
    	
    	printf("Device memory mapped ok\n");
    
    	base = ((unsigned char *)map) + 0x10;

  12. #12
    No positive results yet.
    I looked at parport_splink.c file and i extracted from there the things i thought are used for writing to the port. However, that's without mmap and things like that. But that doesn't work also. I believe that the compile command-line is not right also. Any ideas?
    Oleg, your code only maps the memory, right? Then i have to writeb() at base? Or do i need to do more complex things?

    There is a similar thread on Q&A where someone apparently did a module for controlling the LPT. I think i'll wait for his reply because it states that the module works.

    In the end, it sounds that it's really rocket science to blink those d**n data lines.

  13. #13
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    no, just compile as usual. no writeb is needed.

  14. #14
    can you post a complete example (.c) which blinks the data lines with a 1 sec interval? And which command should i use to compile it?
    That would be more than helpful

    ps: with this wl500g i realised that embedded programming is not that easy as x86

  15. #15
    Any idea? Anyone?

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