Hi,
definition of TOS_MSG in tinyos1.x is as below:
typedef struct TOS_Msg
{
/* The following fields are transmitted/received on the radio. */
uint16_t addr;
uint8_t type;
uint8_t group;
uint8_t length;
int8_t data[TOSH_DATA_LENGTH];
uint16_t crc;
/* The following fields are not actually transmitted or received
* on the radio! They are used for internal accounting only.
* The reason they are in this structure is that the AM interface
* requires them to be part of the TOS_Msg that is passed to
* send/receive operations.
*/
uint16_t strength;
uint8_t ack;
uint16_t time;
uint8_t sendSecurityMode;
uint8_t receiveSecurityMode;
} TOS_Msg;
there is a length filed before data filed indicate payload length.When i read
from serial port ,the data is something like:
7E 42 FF FF 16 11 03 0B 21 05 B1 9F 7E
03 is the lenght field and indicate lenght of following data and 0B 21 05 is
data format we defined in our application.
but when i directly receive data with 802.15.4,the data is like:
01 08 01 FF FF FF FF 16 11 0B 21 05 6D 3C FF
01 08 01 FF FF FF FF is the Mac header of 802.15.4,and the length filed is
missing!
so my question is: is the data lenght filed really in the 802.15.4 frame?if not
,what's it used for?
any help would be appreciated!
2008-11-03
Oden
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