CC3220S-LAUNCHXL: Unable to run the 'subscribe_publish_sample' in the SimpleLink CC32XX SDK AWS IoT Plugin.

Hi Steve,

The aws plugin (aws_cc3220_1_00_00_12) was built for simplelink_cc32xx_sdk_1_30_01_03, and hasn't yet caught up with the new sdk 1.40 update which was just released, which I think is why the examples didn't build directly for you.

I think you've made all the changes necessary though, but I think you need one amendment in the linker command file.

    .stack (NOLOAD) : ALIGN(0x8) {
        _stack = .;
        __stack = .;
        KEEP(*(.stack))
        . += 0x800;
        _stack_end = .;
        __stack_end = .;
    } > REGION_STACK AT> REGION_STACK

Could you give that a try please?

~roger

Well, it seems that I am not out of the woods yet. When I ran the example I found that I was unable to connect to the AWS endpoint and I realized that the local time setting was wrong. The problems are related to use of the C Time library <time.h>, specifically use of the functions time() and localtime().

I traced the issue to the call to SNTP_getTime() that is made inside startNTP(). In particular, the callback function setTime() which is passed into and ultimately called from within SNTP_getTime().

There are a few problems in setTime(), but I verified that the argument that is passed to it does correctly represent the epoch time, so the code that obtains a time value from the NTP server is working properly.

The first problem in setTime() is that it makes a call to the system time() function which does not appear to be implemented as the value output by the call to time() is always -1. The call stack shows the following:

time()

   _gettimeofday_r()

      _gettimeofday()

From the .map file I see that the function _gettimeofday() is obtained from gettod.o in the library libnosys.a

I modified the setTime() function to set the ts value to the epoch time passed in through the argument t. This at least provided me with a valid GMT time.

/*
 *  ======== setTime ========
 */
void setTime(uint32_t t)
{
    SlDateTime_t dt;
    struct tm tm;
    struct timespec tspec;
    time_t ts;

    tspec.tv_sec = t;
    clock_settime(CLOCK_REALTIME, &tspec);

    time(&ts);	/* This always returns -1 */
    
    ts = (time_t) t;	/* Added - use the (correct) epoch time passed in to setTime() */
    
    tm = *localtime(&ts);	/* The resulting tm structure is valid but is a UTC time value */

    /* Set system clock on network processor to validate certificate */
    dt.tm_day  = tm.tm_mday;
    /* tm.tm_mon is the month since January, so add 1 to get the actual month */
    dt.tm_mon  = tm.tm_mon + 1;
    /* tm.tm_year is the year since 1900, so add 1900 to get the actual year */
    dt.tm_year = tm.tm_year + 1900;
    dt.tm_hour = tm.tm_hour;
    dt.tm_min  = tm.tm_min;
    dt.tm_sec  = tm.tm_sec;
    sl_DeviceSet(SL_DEVICE_GENERAL, SL_DEVICE_GENERAL_DATE_TIME,
            sizeof(SlDateTime_t), (unsigned char *)(&dt));
}

A call is then made to the function localtime() which does convert the epoch time and return a pointer to a valid tm structure. However, the time in that structure is always represented as UTC time.

Setting the system clock on the network processor to a UTC time value allowed me to at least connect to the AWS endpoint, however I do need to be able to obtain the local time.   Also, even with the modification that I made the output to the console still reports the wrong time because it is relying on another call to the time() function, which again always returns -1.

Is there a way to fix this example so that the C Time library works properly? The other two examples in the SimpleLink CC32XX SDK AWS IoT Plugin (shadow_sample and shadow_sample_console_echo) also rely on the C Time library.

Thank you,

Steve