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Forum Index : Microcontroller and PC projects : MMbasic 5.3 Requests.

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retepsnikrep

Senior Member

Joined: 31/12/2007
Location: United Kingdom
Posts: 134

Posted: 07:41am 26 Apr 2017

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Having had a look through the MMBasic source I can see the PIC internal pullup/down is being set to prevent the Com port RX pins from floating.

Could I ask that it be included as an option rather than mandatory in the next version of MMBasic for the Extreme 144.

I have external pull ups in my application due to fixed higher voltage hardware i'm talking with (5 & 12V).

In this situation the internal pull ups prevented me from using a simple series resistor and diode solution into the RX pin as described in the MMBasic manual.

Many Thanks..Edited by retepsnikrep 2017-04-27

Gen1 Honda Insights.

matherp
Guru

Joined: 11/12/2012
Location: United Kingdom
Posts: 10196

Posted: 08:15am 26 Apr 2017

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The "weak" pullup on the PIC MX chips is roughly 66K (50uA @ 3.3V) and 82K (40uA @ 3.3V) on the MZ so there should be no issue in overcoming it to get below the low voltage threshold. Is your source already high impedance before the resistor/diode clamping?

retepsnikrep

Senior Member

Joined: 31/12/2007
Location: United Kingdom
Posts: 134

Posted: 08:43pm 26 Apr 2017

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Peter I will try to keep it all in the other thread. i have replied on there.. Thanks

Gen1 Honda Insights.

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