An object to create 'NowSec'

Comments

• Mickster Posts: 1,631

  2019-12-29 - 15:30:32

  Well my solution would be to use a micro with a 64b timer. I use a good number of Micromites anyway so for ~$5 I would have that feature plus I/O expansion, I2C, SPI, analog, etc.
• ersmith Posts: 3,928

  2019-12-29 - 15:40:28

  If @Erlend has a spare cog then there's no need for another chip. I'd just write a simple Spin function to increment a timer every second, something like:

  '' WARNING: this is untested code, it's just a proof of concept
  ''
  VAR
     long seconds_since_boot
     long stack[8] ' probably bigger than needed
  
  '' function to increment seconds_since_boot once per second
  PRI timer | next, freq
    freq := _CLKFREQ
    next := CNT
    repeat
      waitcnt(next += freq)
      seconds_since_boot++
  
  '' call starttimer to start the timer
  PUB starttimer
    cognew(timer, @stack)  ' run the timer function in a new COG
  
  '' call gettimer to get the integer count of seconds since boot
  PUB gettimer
    return seconds_since_boot
  
• Rayman Posts: 10,489

  2019-12-29 - 16:20:16 edited 2019-12-29 - 16:20:33

  Here's PropTime, where you use a cog (doesn't have to be dedicated) to act as a RTC:
  rayslogic.com/propeller/Programming/RTC/PropTime.zip
  
  Posted about it here a long time ago: https://forums.parallax.com/discussion/106263/proptime-unix-style-rtc-using-one-cog/p1
  
• JonnyMac Posts: 6,600

  2019-12-29 - 19:55:01 edited 2019-12-29 - 20:23:05

  Almost all of my commercial programs have a background process for low-bandwidth housekeeping chores. This code runs in a 1ms loop (you can do a surprising amount of work in a millisecond -- even in Spin), so it's great for time-keeping.
  
  I've attached a little demo that shows how I use my background process. If you don't have a spare cog, my time object (jm_time_80.spin) will keep running count of milliseconds as well -- the difference is that you MUST access one of the methods that call the mark() method in that object before the cnt register runs a full, 32-bit cycle (about 53 seconds at 80MHz). Use of this is easy, just call time.seconds when you want to know the elapsed seconds. I'm doing this in the demo as well.
  
  I created jm_time_80.spin because I was coding a laser-tag controller and needed a bunch of timers, but had no available cogs (hence no background process). Thankfully, it all worked out well. If you don't need to do anything else as a background process, it's a good way to go (as others have shown with similar code).
  
  It can be this easy to change the state of the LED based on the time since boot.
  

  obj
    runtime : "jm_time_80"
  
  pub main
  
    runtime.start
    dira[LED] := 1
  
    repeat
      outa[LED] := runtime.seconds & 1
  

  zip

  zip

  jm_background_timer - Archive [Date 2019.12.29 Time 12.22].zip

  19K
• Erlend Posts: 605

  2019-12-30 - 08:09:52

  Incredible. I did not imagine you guys had so many good solutions up your sleeve. I love the idea to put one of the cheap micro controllers lying around to use, but then I'd have to do C programming - which is no fun. In this particular application the jm_time_80 is a brilliant solution, since my main code has a cycle that repeats (irregularly) every few seconds, and therefore can do the required mark call.
  Thanks a lot!
• kwinn Posts: 8,517

  2019-12-30 - 17:35:52

  Erlend wrote: »

  Incredible. I did not imagine you guys had so many good solutions up your sleeve. I love the idea to put one of the cheap micro controllers lying around to use, but then I'd have to do C programming - which is no fun. In this particular application the jm_time_80 is a brilliant solution, since my main code has a cycle that repeats (irregularly) every few seconds, and therefore can do the required mark call.
  Thanks a lot!

  
  If someone had the time to go through all the posts and collect the code and ideas posted by the forumistas over the years it would probably cover 99% of the code needed for any project.