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Grogster

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Joined: 31/12/2012
Location: New Zealand
Posts: 9751

Posted: 04:41am 13 May 2018

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As per title, is there a HS comparator or a way of doing same within MM?

This is related to my other thread about model railway DCC ideas, and along with another page that posted a circuit for easily multiplexing UART serial across a low-voltage power line. She uses a HS comparator inside another PIC chip, but I don't seem to recall that the MM has that ability, unless I am missing something obvious - which I probably am.....

Failing that, I will use an external HS comparator such as the TS3011. But if the MM can do it, then that saves another three bucks for the external HS comparator is all.

Smoke makes things work. When the smoke gets out, it stops!

panky

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Joined: 02/10/2012
Location: Australia
Posts: 1116

Posted: 11:10am 13 May 2018

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G,

Don't know if there is a high speed comparitor but the following function takes about 230 uSec on a MZ running at 252MHz. Enter with 2 analogue in pins as a and b
You could optionally add a third variable which determines the hysteresis - in the example below I have set it at +/- 10 so with the 12 bit ADC in the MZ, this would be roughly 0.5%

function CompAB(a,b)
if pin(a)+10 > pin(b)-10 then CompAB = 1
els eif pin(a)+10 < pin(b)-10 then CompAB = -1
else
CompAB = 0
endif
end function

panky

... almost all of the Maximites, the MicromMites, the MM Extremes, the ArmMites, the PicoMite and loving it!

matherp
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Joined: 11/12/2012
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Posted: 12:13pm 13 May 2018

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Quote As per title, is there a HS comparator or a way of doing same within MM?

Yes - see datasheet. However, using it would be tricky even in a CFunction as you can't get access to the interrupt

Grogster

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Posted: 11:50pm 13 May 2018

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Lovely, thanks chums.

External HS comparator it is, if I elect to go down that path.

Smoke makes things work. When the smoke gets out, it stops!

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