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  1. bob weir

    Digital programmable CDI ignition for 2-stroke engines

    ok troops , a preview of the delay time calculations is in order. so you can start thinking about whats going on here . this is being done in lieu of a table of numbers. that will follow in a later post. today you get a glimpse of what they are based on. lets look at code execution time...
  2. bob weir

    Digital programmable CDI ignition for 2-stroke engines

    now that a better ,-71 deg , reference point is known the actual delays needed for every rpm-range can now be measured. the MPASM timing tool will be used to do this. the sizes of these delays determine the nature of the subroutine that will be used to implement them. a table of...
  3. bob weir

    Digital programmable CDI ignition for 2-stroke engines

    the cursors show 123.2 ms between the + half-sine signals. then the right cursor was moved to the left - half-sine and a 3-signal average of 21.0 ms was mesured. the 3 -signal avg for the period was 122.0 understand that from the first + half wave to the 2'd + one is one rev of the...
  4. bob weir

    Digital programmable CDI ignition for 2-stroke engines

    this scene shows the Rigol 1054 scope recording the timing signal that comes off the flywheel magnet during the spin via the starter motor. with the spark plug removed good signals were obtained. by 'good' is meant the time between the 2 + half-sine waves was within 1% of the time between the...
  5. bob weir

    Digital programmable CDI ignition for 2-stroke engines

    dear reader , this post was going to be on the topic from the flow diagram. the one posted on july 25. its the box that begins "delay the amount of time ...". well , i was poised to post a table of time delays for each of the RPM ranges. the starting point was going to be the -60/-70 deg...
  6. bob weir

    Digital programmable CDI ignition for 2-stroke engines

    one thing that influences the code doing its job is the speed of the uC. the 12F508 is using its built-in 4mhz oscillator. and the instruction cycle is 1 uS. most instructions take one microsecond to execute. this graph shows the amount of time there is for the ignition code to do its...
  7. bob weir

    Digital programmable CDI ignition for 2-stroke engines

    this post will look closer at the range test code posted on aug 18. a week ago. one matter to make light of is the test code using the variable 'nmbr' and fixed values .195 , .117 ... etc. in each test. all of them are analogs of the period of the flywheel rotation. nmbr is the actual period...
  8. bob weir

    Digital programmable CDI ignition for 2-stroke engines

    dear reader ... for this code business a helpful link is the one posted last sept 25 , 2014 with the URL for Gooligum. the person behind that site wrote a series of lessons for a beginner to learn MPLAB assembly language. and in his baseline series lesson 5 for TMR0 on p. 5 / 17 is some...
  9. bob weir

    Digital programmable CDI ignition for 2-stroke engines

    here is the same range test code that can be moved to MPLAB IDE s/w and made into a project. once that is done ( for help see lesson 1 of the Gooligum baseline lessons ) you can open the simulator tool and run the code one line at a time. doing this allows viewing the windows containing the nmbr...
  10. bob weir

    Digital programmable CDI ignition for 2-stroke engines

    hey troops , here is a piece of sample code that does the range test. it takes the TMR0 value for one period then finds which RPM range box it goes in. see the previous posting for the image of red RPM range boxes overlaid on the deg-adv. vs rev/min image.
  11. bob weir

    Digital programmable CDI ignition for 2-stroke engines

    for the next code block, the one that does the range-test for RPM's this message purpose is to propose that you now take a look at the simulator tool that comes with MPLAB IDE. the reason is that the code is tricky to follow. oh, the idea is simple enough, compare 2 numbers and...
  12. bob weir

    Digital programmable CDI ignition for 2-stroke engines

    this graphic includes the red rectangles to illustrate the 'RPM-range' idea introduced earlier. this PIC12F508 uC works with integer numbers only. and these 8-bit numbers are all in the range 0 to 255 , so we are further restricted. if this PIC12F508 uC were math-enabled and could handle...
  13. bob weir

    Digital programmable CDI ignition for 2-stroke engines

    aug 11 2015 details of block of ignition code flow diagram for 12F508 this is the 2'd block posted earlier, 7-25 i think it was ... ...its the block after the start oval that cites detecting -60/-70 pulses steps : 1. detect a -60/-70 deg input pulse 0 --> 1 logic level change...
  14. bob weir

    Digital programmable CDI ignition for 2-stroke engines

    for every shaft revolution the TMR0 code places a period value in a UDATA variable. this period is a RPM representation. and it somewhere along the r/min graph line. next the code will do some range-test code then know better where on the graph the period goes. the size of these ranges is...
  15. bob weir

    Digital programmable CDI ignition for 2-stroke engines

    the post today is a detailed version of the 1'st block in the flow diagram above. on july 25. the 'setup- the - uC' block
  16. bob weir

    Digital programmable CDI ignition for 2-stroke engines

    here is flow diagram for the uC code that makes the CDI fire and run the engine. right now what is being looked at is to just provide code for each block of the diagram . or to do a follow-up flow diagram with more detail. what i'm stumbling over is the setup block referring to instruction...
  17. bob weir

    Digital programmable CDI ignition for 2-stroke engines

    hi guys , on re-reading the most recent posting some clarification is called for: 1. the first timing signal is in the -70 to -60 deg BTDC area , exactly where is not known yet. but it will ................. worked out later , so dont sweat it if we dont...
  18. bob weir

    Digital programmable CDI ignition for 2-stroke engines

    dear reader - there is some circuitry not yet covered. instead of that today we are moving along to the code. we'll get back to the circuit later. getting a CDI circuit design , built and tested is one of the major tasks for this project. and a person can find many CDI circuits online. the...
  19. bob weir

    Digital programmable CDI ignition for 2-stroke engines

    shanky , thank you for the respect. i'm not so great. just a guy trying to understand how to do something new. that will end up with my motorcycle back on the road. and you dont have to call me sir either. it is good you found this site. its lots more than i had back when i was...
  20. bob weir

    Digital programmable CDI ignition for 2-stroke engines

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