[ts-7000] Potential problem reading RS-485 present status on TS-7350

["Sean" <>]

I'm trying to read the location 0x22400000 on my TS-7350 to determine
if RS-484 is installed, as per section 5.8 in the manual.  My code
below returns 0 for a read at that address however, and the board I
have should have RS485 installed.  Can anyone see anything incorrect
in my program or suggest what else could be going wrong?

-----------------------------------------------------------------
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <unistd.h>

/*
 * Simple program to determine if RS485 is installed on a TS-7350.
 * See section 5.8 of
ftp://ftp.embeddedarm.com/ts-arm-sbc/ts-7300-linux/manuals/ts-7300-manual-rev1.4.pdf
 *
 */
int main() {

    int ret = EXIT_FAILURE;
    int fd = open("/dev/mem", O_RDWR|O_SYNC);

    if (fd != -1) {
        volatile unsigned char* p = mmap(0, getpagesize(), PROT_READ,
MAP_SHARED, fd, 0x22400000);
        if (p != MAP_FAILED) {
            printf("register value is 0x%02x\n", *p);
        }
        else {
            perror("mmap failed");
        }
        close(fd);
        ret = EXIT_SUCCESS;
    }
    else {
        perror("open failed");
    }

    return ret;
}



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