# Software Meeting 07/08/2003 **Attendees:** - [[IanOsgood]], [[BartMassey]], [[JamesPerkins]] **Timestamp discussion:** - [[JamesPerkins]] went through the current ideas. Last week we thought of a 32-bit seconds count, and a 16-bit subsecond count, 7 bits of which are the 100Hz Linux timer. The remaining bits are a serial number of the message within the same 1/100 of a second. - Problems with this include: who decides when to timestamp things? Messages may languish in various FIFOs, or it may be a while before they get sent, etc. - It's probably only really important to count when they are read from or written to the CAN driver; the can\_rdr\_wtr task can assign this. Everything else, within 1/100 of a second of when they first generated is probably good enough. Things **will** arrive out of order, we should expect it. - Bart suggested a 100 Hz resolution real time timer, and a monotonically increasing serial number of some large number of bits, have it in one place and added along with the real time timer.
# bits Use
32 Seconds since epoch
7 1/100 second Linux counter
25 FC sequence counter
- The 32 + 7 bits can be determined from gettimeofday(2). - The 25 bits need to be retrieved from a single source. I suppose a device driver needs to be written to do this. -- [[JamesPerkins]] - 08 Jul 2003