[Tinyos-help] CTP Data Frame take the message_t data ?

[Pedro Almeida]

Hello, Daniel;

What i can tell you (don't take this as exact, i'm an amateur) is that the
message_t contains within the CTP data field, inside of which there is the
actual data payload you desire (check TEP 123, point 4), all up to a maximum
of
TOSH_DATA_LENGTH. Up to, because you can have less, data_length is
just a limit to be filled, the actual payload size is set in the Frame
Length byte, as defined in the cc2420 header:

typedef nx_struct cc2420_header_t {
nxle_uint8_t length;   ««« here's the payload length, which starts counting
in the "type" byte down there
nxle_uint16_t fcf;
nxle_uint8_t dsn;
nxle_uint16_t destpan;
nxle_uint16_t dest;
nxle_uint16_t src;
nxle_uint8_t type;   « this byte here is already part of the payload as is
considered in the length above
cc2420_header_t;

hope this is any help

regards

Pedro


On 7/10/07, Daniel Widyanto <danielw at wireless-people.com> wrote:
>
>
> Hi all,
>
> I just want to ask about the package frame.
>
> Based on TEP111 about message_t, the message_t's
> data length is defined by TOSH_DATA_LENGTH.
>
> Is the CTP's data frame (in TEP123 section 4) taking
> message_t's data field ? Or is the message_t is
> inside the CTP's data field ?
>
> Just a bit confuse
>
> Thanks
>
> Regards,
>
> -daniel
>
>
>
>
>
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