call LocalTime.get() gives you the local time on the node. If you want to access the global time on the node then you need to use the call GlobalTime.local2Global(&mylocaltime) command. Here mylocaltime is the return parameter of call LocalTime.get(). I think what you need to do is compare global times at sender and receiver. Also conversion from local time to global time requires an offset as well as a skew.
- TinyOS MAC does an initial backoff and CCA before a packet is sent out. - Regarding acks... by default acks are activated, if you want to disable them, include CFLAGS += -DCC2420_NO_ACKNOWLEDGEMENTS in your MAKEFILE. Regards Akhila > > Hi everybody, > I'm working on implementing Schedule-based MAC protocol and I apply FTSP > for > time synchronization (use telosb mote). > I use AMSend/ActiveMessageC interface to send and receive messages. > Timestamp is made before sending message (or after receiving message as > well) by using the command 'call LocalTime.get()'. > And then, the receiver can calculate timeOffset = Global time - Local time > However, the value of timeOffset is changed very much with each message, > so > the estimated global time is not correct. This error can be the timestamp > problem. Please help me if you have any experience on this. It's very > urgent. > Some more questions: > 1. How can I make timestamp at the moment before the message is sent to > environment (close to physical layer as possible to reduce delay)? > 2. Whether the AMSend interface performs RTS/CTS or senses the channel > before sending the message > Because each node is assigned slot for sending DATA message, so there is > no > need to use RTS/CTS. > But for other type of message, it needs RTS/CTS to compete the channel. > How > can I do this? > 3. Because it can use software/hardware Acknowlegment by default. How can > I > add some information into ACK message or disable both software and > hardware > ACK to use my own ACK? > > Thank you very much! > Best regards, > Bin > -- > View this message in context: > http://old.nabble.com/Timestamp-problem-tp33544786p33544786.html > Sent from the TinyOS - Help mailing list archive at Nabble.com. > > _______________________________________________ > Tinyos-help mailing list > Tinyos-help@millennium.berkeley.edu > https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help > > -- > This message has been scanned for viruses and > dangerous content by MailScanner, and is > believed to be clean. > -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean. _______________________________________________ Tinyos-help mailing list Tinyos-help@millennium.berkeley.edu https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
