[Tinyos-devel] TimeSyncMessageC vs. AMSenderC

[Miklos Maroti]

Hi,

After a discussion with Phil we decided that the best way to solve the
FTSP + CTP send clash problem is to use the AMSenderC infrastructure
for the TimeSyncMessageC implementation. I have updated the RF230
radio driver accordingly (required only a couple of changes), however
we expect this to be revisited when we decide the fate of message_t
and how different layers interact with each other. Just for the
record:

1. The problem occured when FTSP sends a message via the radio driver
specific TimeSyncMessageC component, which appended the embedded
timestamp and called ActiveMessageC directly. While the ActiveMessageC
was busy transmitting the message and the CTP tries to transmit its
own message via the AMSenderC, then the AMQueueImplP returned the
unexpected FAIL.

2. The solution is not optimal, because time scale transition (for
example from TMilli to TMicro required by the on-air data format)
occurs at TimeSyncSend.send time. This looses accuracy, as all
conversions should occur as close to the actual transmission as
possible.

Miklos