On Sunday 19 August 2007 10:06:30 am Ákos Maróy wrote:
> I'm trying to read the messages sent by the Oscilloscope sample
> application from C.
>
> I generated the C .h and .c file using mig, using the following Makefile
> rule:
>
> oscilloscope_msg.h oscilloscope_msg.c: ../Oscilloscope.h
> mig -target=null c ../Oscilloscope.h oscilloscope -o $@
>
>
> I got a range of functions, like:
>
> uint16_t oscilloscope_version_get(tmsg_t *msg);
>
>
> so far so good. I started to work from source code of prettylisten.c, as
> that already connects to the serial forwarder. basically I added the
> following function:
>
> void oscilloscope_print(tmsg_t *msg) {
> unsigned int version;
> unsigned int interval;
> unsigned int id;
> unsigned int count;
>
> version = oscilloscope_version_get(msg);
> interval = oscilloscope_interval_get(msg);
> id = oscilloscope_id_get(msg);
> count = oscilloscope_count_get(msg);
>
> printf("version: %u, interval: %u, id: %u, count: %u\n",
> version, interval, id, count);
> }
>
>
> and call it after hexprint():
>
> printf("dest %u, src %u, length %u, group %u, type %u\n ",
> spacket_header_dest_get(msg),
> spacket_header_src_get(msg),
> spacket_header_length_get(msg),
> spacket_header_group_get(msg),
> spacket_header_type_get(msg));
> hexprint((uint8_t *)tmsg_data(msg) + spacket_data_offset(0),
> tmsg_length(msg) - spacket_data_offset(0));
>
> putchar('\n');
>
> oscilloscope_print(msg);
>
>
> it all compiles fine. so far so good.
>
> but when I actually run the application, the data that gets printed is
> bogus:
>
> $ ./oscilloscope localhost 9002
> dest 65535, src 65535, length 28, group 0, type 147
> 00 10 01 00 00 01 00 bb 04 fe 04 6e 04 6e 04 ca 04 ca 04 f5 04 f5 05
> 0e 05 0e 04 64
> version: 65535, interval: 65535, id: 7168, count: 37632
>
> dest 65535, src 65535, length 28, group 0, type 147
> 00 10 01 00 00 01 00 bc 04 68 04 55 04 55 04 c9 04 c9 05 08 01 26 02
> 80 02 80 01 32
> version: 65535, interval: 65535, id: 7168, count: 37632
>
> dest 65535, src 65535, length 28, group 0, type 147
> 00 10 01 00 00 01 00 bd 05 6e 03 86 03 86 04 e1 04 e1 05 69 05 69 04
> fa 04 fa 05 62
> version: 65535, interval: 65535, id: 7168, count: 37632
>
>
>
> whereas the interval used is 256, the id of the mote is 1, the count is
> much much lower, etc.
>
> I tried to call oscilloscope_print() with a similar pointer magic as
> hexprint() is called, but then I get a segfault.
How are you instantiating the message object? Here's a code snippet from one
of my programs. Note the arguments to new_tmsg(). It's been so long since I
wrote this code that I can't recall what byte I'm skipping. But, I think
it's the protocol byte. See TEP113 for more info.
packet = read_serial_packet(src, &len);
if (!packet) {
llog(LOG_ERR, "read_serial_packet() fail: %m");
break;
}
if (!(msg = new_tmsg(packet + 1, len - 1))) {
llog(LOG_ERR, "new_tmsg(): mem alloc error");
break;
}
_______________________________________________
Tinyos-help mailing list
[email protected]
https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
