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Joe, That's definitely an improvement! So, that would be a 250 Hz sample rate for any given sensor. I just tried a modification similar to yours that did all 4 conversions every OCRA/B interrupt (or 1 KHz sample rate) and got: IDLE: 82 2ROT: 77 (...) (22 years ago, 15-Jan-03, to lugnet.robotics.rcx.legos)
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| | Re: Interesting BrickOS Timing Results
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(...) Timer B is usually unused but has a lower priority than Timer A. If you do a lot of stuff in the timer A routine, this will block timer B interrupts (especially if timer B generates more interrupts than timer A). The mean thing is that those (...) (22 years ago, 15-Jan-03, to lugnet.robotics.rcx.legos)
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| | Re: Interesting BrickOS Timing Results
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OCRA and OCRB are output interrupts for the 16 bit timer. They can be programmed to fire at specific points along the timers run. So, technically, they cannot be used independently of each other. If OCRA resets the timer value back to zero, then (...) (22 years ago, 15-Jan-03, to lugnet.robotics.rcx.legos)
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| | Re: Interesting BrickOS Timing Results
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(...) My thought was that the OCRA interrupt could be used as the general 1ms interrupt and the subsystem handler (which is currently using OCRB) could be called every other time from the OCRA handler by using a flag (toggled every 1ms). Actually, (...) (22 years ago, 15-Jan-03, to lugnet.robotics.rcx.legos)
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| | Re: Interesting BrickOS Timing Results
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Hi Marc, (...) Nice idea, but wouldn't that result in at least one of four cycles beeing blocked by OCRA? or is our system interrupt finished within less than 250msec? (...) Right, that was what I did for my Lepomux patch - works fine. Gunther (22 years ago, 15-Jan-03, to lugnet.robotics.rcx.legos)
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| | Re: Interesting BrickOS Timing Results
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Mark Riley wrote: > Actually, if we move the sys_time > handler back to OCRA (instead of the watchdog NMI), > then we could just check if bit 0 of sys_time is zero to > determine if the subsystem handler should be called (plus > this will get (...) (22 years ago, 15-Jan-03, to lugnet.robotics.rcx.legos)
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| | RE: Interesting BrickOS Timing Results
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(...) I have been following this thread in my peripheral vision for a while now. All of the talk is very interesting and appears to be leading to a general question about how and why the drivers are the way they are.... As a point of interest, some (...) (22 years ago, 15-Jan-03, to lugnet.robotics.rcx.legos, lugnet.robotics.rcx.pbforth)
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| | Re: Interesting BrickOS Timing Results
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(...) 250msec? Not blocked entirely, but delayed. That's what I meant by "stutter". I've measured the general interrupt handler to take anywhere from 70-150us. So, the higher the sample rate the more significant the disruption. Anything faster than (...) (22 years ago, 15-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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