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Forum Index : Microcontroller and PC projects : More than 4 count Inputs with Webmite ?
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| Gerad Regular Member  Joined: 10/01/2024 Location: GermanyPosts: 42 |
Hello Everybody Is it possible to define more than 4 count inputs with Webmite ? Gerad |
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Mixtel90 Guru  Joined: 05/10/2019 Location: United KingdomPosts: 6783 |
Not actual high speed counter inputs, no. If you only need low speed then you can use any pins and use them to trigger interrupts if you like. They are a lot slower though. Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| Gerad Regular Member Joined: 10/01/2024 Location: GermanyPosts: 42 |
Hi Mick I thought so. Then I probably have to use 2 picomite as count slave controllers for another 8 count inputs. Thank you very much for your information Gerad |
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| Volhout Guru Joined: 05/03/2018 Location: NetherlandsPosts: 4223 |
Hi Gerad. You can use PIO. In the normal pico you have 8 PIO state machines, each can count 1 input. In the VGA pico, you can use only 4 PIO state machines, since the other 4 are used for creating VGA. And, in case they are slow changing inputs, you can count in MMbasic. What is your application, What are you counting ? Regards, Volhout Edited 2024-03-29 22:43 by Volhout PicomiteVGA PETSCII ROBOTS |
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| Gerad Regular Member Joined: 10/01/2024 Location: GermanyPosts: 42 |
Hi Volhout Unfortunately, I have absolutely no idea how the PIO state machines work I count pulses from 12 water flow meters. between 90 and 350 impulses/sec each. Regards, Gerad |
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| matherp Guru Joined: 11/12/2012 Location: United KingdomPosts: 9110 |
Assuming these are clean "non-bouncing" 50% duty cycle signals then you could easily do this in a loop with a port function reading the inputs and comparing with the previous reading. You could do this in say a 1mS timer loop which should catch everything. Something like: settick 1,readpins do 'whatever loop ' sub readpins a%=port(pin spec) new%= (a% XOR last%) and a% 'pins that have changed to ON last%=a% for i%=0 to nummeters%-1 if new% and 1 then inc counter%(i%) new%=new%>>1 next i% end sub |
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| Gerad Regular Member Joined: 10/01/2024 Location: GermanyPosts: 42 |
Thanks matherp for the example. I'm trying to understand it. It makes me uncomfortable, but I have a small question: what does “%” mean, e.g. “new%)? Gerad |
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| matherp Guru Joined: 11/12/2012 Location: United KingdomPosts: 9110 |
% is the syntax that specifies the variable is an integer - see the manual for more details %=integer, !=float, $=string |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 6783 |
It makes the variable "new" an integer. Another way is to use DIM INTERGER new then "new" will always be an integer variable, even without the % symbol. Some people prefer to always use the symbols, others prefer to use DIM to set the type. This stuff is in the manual, it's just a case of finding it. :) Look under "Variables and expressions". Probably around page 40-ish depending on your manual. Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| Gerad Regular Member Joined: 10/01/2024 Location: GermanyPosts: 42 |
Hello matherp , Hello Mick many thanks for your help. I wish you a nice Easter. Regards Gerad |
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| Volhout Guru Joined: 05/03/2018 Location: NetherlandsPosts: 4223 |
Hi Gerad, Peter's proposal works, but requires OPTION CPUSPEED 252000 or OPTION CPUSPEED 378000 to manage 12 count inputs in MMBasic. The standard picomite speed of 133000 is not sufficient for 12 inputs. Below is the program to test this: 'count events on 12 GPIO pins nummeters%=12 dim counter%(nummeters%-1) openpins 'measurement speed settick 1,readpins 'main loop do 'just simulating all the math for 100ms pause 100 'print how much time the interrupt routine takes (out of 1ms tick) 'print t loop 'read all the pins sub readpins 't=timer a%=port(1,2,4,4,9,4,14,2) 'GP0...GP11 new%= (a% XOR last%) and a% 'pins that have changed to ON last%=a% for i%=0 to nummeters%-1 if new% and 1 then inc counter%(i%) new%=new%>>1 next i% 't=timer-t end sub sub openpins setpin 1,din setpin 2,din setpin 4,din setpin 5,din setpin 6,din setpin 7,din setpin 9,din setpin 10,din setpin 11,din setpin 12,din setpin 14,din setpin 15,din end sub When you "un-comment" lines 15,20,28 it gives you the time consumed in the interrupt routine. At 252MHz (CPUSPEED 252000) that is 62% (0.62ms of 1ms), and that will be barely enough to run a responsive main program. Most time is consumed in this section of the interrupt routine 0.5ms of 0.62ms. for i%=0 to nummeters%-1 if new% and 1 then inc counter%(i%) new%=new%>>1 next i% Maybe there is a faster way of doing this, that would be good. But I have no alternative yet. Minor speed up can be achieved by NEXT in stead of NEXT i% And defining nummeters% as 11 (in stead of 12) to ommit the math in the interrupt routine. for i%=0 to nummeters% in stead of for i%=0 to nummeters%-1 That would bring you to 0.56ms (from 0.62ms) every 1ms interrupt Volhout EDIT: this brute force interrupt routine is faster (0.44ms).... sub readpins t=timer a%=port(1,2,4,4,9,4,14,2) new%= (a% XOR last%) and a% last%=a% inc counter%(0),(new% and 1=1) inc counter%(1),(new% and 2=2) inc counter%(2),(new% and 4=4) inc counter%(3),(new% and 8=8) inc counter%(4),(new% and 16=16) inc counter%(5),(new% and 32=32) inc counter%(6),(new% and 64=64) inc counter%(7),(new% and 128=128) inc counter%(8),(new% and 256=256) inc counter%(9),(new% and 512=512) inc counter%(10),(new% and 1024=1024) inc counter%(11),(new% and 2048=2048) t=timer-t end sub Edited 2024-03-31 02:22 by Volhout PicomiteVGA PETSCII ROBOTS |
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phil99 Guru Joined: 11/02/2018 Location: AustraliaPosts: 2135 |
To shave off a few more uS use single character variable names and try to squeeze loops into a single line with minimum white-space. Every character takes time to read. new% caused an error as New is a keyword, changed to newm%. for i%=0 to nummeters%-1 if new% and 1 then inc counter%(i%) new%=new%>>1 next i% Becomes Dim Integer i, m, n, c(nummeters%-1) m = nummeters%-1 : n = newm% '... For i=0To m:If n And 1 Then:Inc c(i):EndIf:n=n>>1:Next Edit. If the number of meters is always the same replace the variables nummeters% and 'm' with the number. Looking up the value of variables / constants takes time. For i=0To 11:If n And 1 Then:Inc c(i):EndIf:n=n>>1:Next timer=0:For i=0To 11:If n And 1 Then:Inc c(i):EndIf:n=n>>1:Next:?timer 0.335 > ? mm.info(cpuspeed) 378000000 > PS. You can remove the space before 'To' but not the one after it. Edited 2024-04-27 10:53 by phil99 |
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| matherp Guru Joined: 11/12/2012 Location: United KingdomPosts: 9110 |
INC N,N is a fair bit faster than N=N>>1 Edited 2024-04-27 17:46 by matherp |
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| Volhout Guru Joined: 05/03/2018 Location: NetherlandsPosts: 4223 |
Hi Phil, Avoiding the loop is faster. See my post before. I get 0.44 ms at 252Mhz. That would be 0.29 at 378Mhz. Volhout PicomiteVGA PETSCII ROBOTS |
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| Gerad Regular Member Joined: 10/01/2024 Location: GermanyPosts: 42 |
Thank you very much for all the good suggestions and examples.   Regards Gerad |
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| JohnS Guru Joined: 18/11/2011 Location: United KingdomPosts: 3800 |
The point is well made, though I think that would be instead of N=N<<1 John |
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