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| As I was poking around in the BrickOS kernel, it occurred to me that using the sys_time variable isn't entirely safe. Since sys_time is 32-bits and the processor can only read 16-bits at a time into a register, there is a period of time between the (...) (22 years ago, 12-Dec-02, to lugnet.robotics.rcx.legos)
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| | Re: sys_time (long post)
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| (...) It turns out that the nature of the glitch depends on the order you read the upper and lower 16-bits of sys_time. If the compiler generates code that reads the high word first (which it seems to do), then your example will work. However, if (...) (22 years ago, 13-Dec-02, to lugnet.robotics.rcx.legos)
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| | Re: sys_time (long post)
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| Does the H8 let an interrupt interrupt an interrupt? (Or at least the interrupts that matter in this case?) You two might want to check on that. It would seem the code is safe if the answer to the first question is no... ? Maybe I'm missing (...) (22 years ago, 13-Dec-02, to lugnet.robotics.rcx.legos)
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| | brickOS is slower than NQC for sending message
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| I tested two ways with brickOS and NQC, source as below, you will find the NQC can only send about 80 messages in 4s, brickOS can send all 255 messages, but need 20s, in other word, NQC needs 50ms for sending a message, or brickOS needs above 100ms (...) (16 years ago, 26-Jun-08, to lugnet.robotics.rcx)
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| | Re: sys_time (long post)
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| Mark, Excellent Post ! Ok, I will admit it; I was the one that put the sys_time handler on the NMI. 8-) I guess I will want to think about this a bit; but I see that you have done a good bit of that yourself. ... Could the 'Get' function do the (...) (22 years ago, 12-Dec-02, to lugnet.robotics.rcx.legos)
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| | Re: Polling sensor values with wait_event
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| Thomas, I had a thought about this situation. You could write a function that sets a flag when the event is triggered, do nothing otherwise. You could call this function from within each of the tasks you write (at a somewhat high frequency ... say (...) (22 years ago, 28-Nov-02, to lugnet.robotics.rcx.legos)
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| | Re: sys_time (long post)
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| Only a suggestion, In any processor architecture (with or without disabling or recursive interrupts) when I need to read timers with more than 1 single instruction I do the following: Read the timer (both low and high value) until I get 2 times the (...) (22 years ago, 16-Dec-02, to lugnet.robotics.rcx.legos)
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| | Re: Float and int
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| (...) For most brick projects I can think of, it is. If you want to travel your robot around, you will have to deal with sin, cos, tan and square root. First thing you can do is working with tables to avoid "on the fly" sin calculation. Second, you (...) (22 years ago, 30-Dec-02, to lugnet.robotics.rcx.legos)
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| | Re: Interesting BrickOS Timing Results
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| (...) The delay was added a long time ago after a bit of discussion on this newsgroup/list. A search through old newsgroup posts will turn up a brief series of three posts with subject "Rom sensor read routine" from Apr/May 1999. The explanation (...) (22 years ago, 15-Jan-03, to lugnet.robotics.rcx.legos)
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| | Interesting BrickOS Timing Results
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| Hi All, The recent posts about interfacing an i2c device to an RCX sensor port (in .robotics) got me interested in looking at the kernel code that handles the sensors. So, I did and found myself looking at the ds_handler function. This function is (...) (22 years ago, 14-Jan-03, to lugnet.robotics.rcx.legos)
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| | Re: Interesting BrickOS Timing Results
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| (...) I forgot to mention... This is *almost* the same as moving some of the subsystem code into a seperate high priority task. For example, LCD refresh code is executed in the 1ms timer ISR. It really doesn't need to be in the ISR. It can do it's (...) (22 years ago, 15-Jan-03, to lugnet.robotics.rcx.legos)
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| | Re: Sensor Sampling; Progress?
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| The Lego firmware cuts power for about 200uS, with a period of 3mS. So most sensors have to have enough capacitor based power storage for the full 200uS and be able to run on about 93% duty cycle. (The rotation sensor is one of the devices on the (...) (22 years ago, 19-Jan-03, to lugnet.robotics.rcx.legos)
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| | Re: Sensor Sampling; Progress?
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| (...) Yes. (...) individually (...) That's right. (...) I agree. With the current firmware, power gets cut off to all 3 sensors for ~85us (sometimes longer). With the scheme I mentioned, power would be cut to only one sensor for ~25us. The sample (...) (22 years ago, 19-Jan-03, to lugnet.robotics.rcx.legos)
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| | Re: newbie troubles (now they in packs of 2)
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| I had exactly the same problems not so long ago so i followed the instructions from this site and uninstalled the brickos i had and used the one they had provided following the link. So go to this site (URL) let me know how you get on. Good luck (...) (22 years ago, 3-Feb-03, to lugnet.robotics.rcx.legos)
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| | Is there a NQC HowTo out there someplace?
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| Hello, I have reached the limits of what Mindstorm 2.0 software can do a long time ago and now want to go further. I think I would try the NQC. My problem is that I do not know anything about C or NQC. I have learned Pascal and Basic language (and (...) (22 years ago, 1-Feb-03, to lugnet.robotics.rcx.nqc)
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| | Re: frame RCX reply how
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| (...) Bingo! I reached the bricktools/ of the frame-free: (URL) bytes At a glance, I missed how bricxcc toggles x08 in the command op to let command ops be repeated, but I'd now guess the bricxcc algorithm for framing standard RCX replies is: 1) (...) (22 years ago, 1-Feb-03, to lugnet.robotics.rcx)
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