ramanathan, just a couple of notes to add to mike's good answers:
if you want sub-second packet stamping, take a look at the localtime interface (a few apps in the apps and swtest directories use it.).
as for ntp, since it is an ip-transport based protocol (udp), you can also consider using one of the 6lowpan implementations in tinyos; porting ntp would not be too hard, as the udp layer is already written and tested in blip (see tos/lib/net/blip). basically ntp is a simple connectionless client-server app; you send a request for a timestamp to a server, and get a packet back with same. the tos-1.x implementation will port directly. it sends a request upon start-up, starts a timer with a 10-minute interval (iirc), and everytime it fires, you get another timestamp; the application sees an event with the new timestamp, which can then be used to set/correct the shimmer system time (presumably you set it in the first place, see HostTimeLogging for an example).
i hope that this helps, steve On 01/11/11 04:23, mike healy wrote:
I'm not really sure what you are looking for in (1). Are you talking about streaming the data or logging it? It might be helpful to take a look at the SimpleAccel application (http://tinyos.cvs.sourceforge.net/viewvc/tinyos/tinyos-2.x-contrib/shimmer/apps/SimpleAccel/) and the associated python script in the same folder. There is an NTP implementation for the shimmer available in TinyOS version 1. Take a look at TestNTP (http://tinyos.cvs.sourceforge.net/viewvc/tinyos/tinyos-1.x/contrib/handhelds/swtest/TestNTP/). However, I've never used this myself, so I'm not entirely sure how it works other than it uses the microIP stack for communication (take a look at the video here to see how to get this stack up and running: http://www.shimmer-research.com/research-2/microip-example). Also, you should know that version 1 of TinyOS is deprecated and shouldn't really be used for new projects. So you could either port this implementation to tinyos version 2 or else run NTP on the basestation (laptop or PC probably) and send the time to the shimmers any way you like. Mike On Mon, Oct 31, 2011 at 5:29 PM, Ramanathan Subramanian <[email protected] <mailto:[email protected]>> wrote: Hi I am working with the Shimmer accelerometer+gyroscope platform for head-pose estimation, and have a few questions to ask. I hope someone can kindly answer them: 1. I just downloaded TinyOS on my desktop (not using the Live CD distribution). Are there any sample codes available on http://www.shimmer-research.com/r-d/software or http://www.shimmer-research.com/download which I can use to dump the time-stamps and ADC outputs from the sensor (instead of having to open the CSV file where this data is saved)? 2. More importantly, I need to synchronize the time-stamps of the Shimmer platform to an NTP server in order to sync with a set of cameras. Any suggestions regarding how I can do this? Thanks very much in advance. Ram _______________________________________________ Shimmer-users mailing list [email protected] <mailto:[email protected]> https://lists.eecs.harvard.edu/mailman/listinfo/shimmer-users _______________________________________________ Shimmer-users mailing list [email protected] https://lists.eecs.harvard.edu/mailman/listinfo/shimmer-users
_______________________________________________ Shimmer-users mailing list [email protected] https://lists.eecs.harvard.edu/mailman/listinfo/shimmer-users
