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Helpful ReplyHot!MCC mapping pins

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_dex
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2020/11/25 06:36:26 (permalink)
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MCC mapping pins

Why when I select some of the pins to my SPI1 interface they make entire row orange and the last two  make not?
Entire row orange means for me it was selected and no other pin can be mapped again, but last two makes only green Padlock. Is this a bug or what does it mean?
I recorder video:
 
https://autode.sk/37a0pbB
post edited by _dex - 2020/11/25 06:46:04
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du00000001
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Re: MCC mapping pins 2020/11/25 08:17:43 (permalink)
2.67 (3)
Look at the "Direction" column:
  • How would you assign multiple pins to a single input signal ?
And to answer your question: the only bug is the bbkac.

PEBKAC / EBKAC / POBCAK / PICNIC (eventually see en.wikipedia.org)
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_dex
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Re: MCC mapping pins 2020/11/25 08:23:12 (permalink)
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that is clear for me, so why after selecting last two pins entire rows goes not in to orange?
 
Does it mean that I can route for example MOSI (SDO1)signal to more than one pin, two pins parallel?
post edited by _dex - 2020/11/25 08:33:52
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du00000001
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Re: MCC mapping pins 2020/11/25 08:36:34 (permalink)
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_dex
that is clear for me, so why after selecting last two pins entire rows goes not in to orange?
 
Does it mean that I can route for example MOSI signal to more than one pin, two pins parallel?



Obviously, nothing (or not much) is clear for you: the last 2 pins are output signals. You basically could attach multiple output pins to the same signal - irrespective whether this does really make sense or not. (And most likely without considerations about the fan-out of the signal source.)

PEBKAC / EBKAC / POBCAK / PICNIC (eventually see en.wikipedia.org)
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_dex
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Re: MCC mapping pins 2020/11/25 13:27:38 (permalink)
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What is a problem actually to connect two pins to one input? I do not see any when you drive signals to these pins via diodes you get nice OR function.
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ric
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Re: MCC mapping pins 2020/11/25 14:37:22 (permalink) ☄ Helpfulby _dex 2020/11/26 00:41:35
5 (2)
_dex
What is a problem actually to connect two pins to one input? I do not see any when you drive signals to these pins via diodes you get nice OR function.

That is not how the function is implemented inside the PIC.
For input signals, there is a multiplexer which is programmed to select ONE of its inputs to the peripheral's input.
That means MCC will only let you select ONE signal to connect to.
You can drive as many output pins as you want from a peripheral output signal.
Read the PIC datasheet to see how the PPS mapping is controlled, and this will become plain to you.
 

I also post at: PicForum
Links to useful PIC information: http://picforum.ric323.co...opic.php?f=59&t=15
NEW USERS: Posting images, links and code - workaround for restrictions.
To get a useful answer, always state which PIC you are using!
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du00000001
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Re: MCC mapping pins 2020/11/25 15:22:39 (permalink)
4 (1)
_dex
What is a problem actually to connect two pins to one input? I do not see any when you drive signals to these pins via diodes you get nice OR function.



Obviously you know nothing or next-to-nothing (I bet on the former) about signal theory etc.:
While it is possible to connect several signal sinks to a single signal source, it is just impossible to connect a signal sink to more than one signal source.
In other words: when you'd connect an internal signal to 2 different input pins: the signal from which of these 2 pins do you expect to be processed further ?

PEBKAC / EBKAC / POBCAK / PICNIC (eventually see en.wikipedia.org)
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Mysil
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Re: MCC mapping pins 2020/11/25 15:46:07 (permalink) ☄ Helpfulby _dex 2020/11/26 00:39:29
5 (1)
Hi,
The input signal selector in PPS, is a 1 out of N selector/multiplexer.
See Wikipedia: https://en.wikipedia.org/wiki/Multiplexer
Each input selector belong to a input signal of a peripheral, and can only select one signal at a time.
If you have made a mistake, or want to change a selection,
then you may click on the green 'lock' icon, to unlock the selection, and select something else.
 
You may select the same pin as input for another peripheral.
And you may select a pin that have been set as output for one signal, as input for another peripheral.
Such a selection will show up with a 'Chainlink' icon.
 
Fan-out of pin signals isn't so much of a concern with cmos logic.
Each pin have it's own output driver amplifier, so the signal passed by PPS multiplexer is only control signal,
not pin output current.
Anyway, all signals that may be selected, are permantly connected to all the multiplexer inputs that may use it,
so wether two different multiplexers select the same signal, do not matter.
 
Also, each pin have it's own input buffer, feeding signals to all the multiplexers that may use the signal.
 
There have been bugs and unnessary limitations in MCC pin setup.
Among other in connection with Oscillator pins. The crystal oscillator amplifiers for Primary crystal oscillator,
and for Secondary Crystal Oscillator, are essentially analog amplifiers with some gain control and other tricks,
and have nothing to do with digital tristate output setting.
Crystal oscillator circuits have its own control over the pin drivers, 
so override eventual setup mistake made by MCC.
This seem to have become better in the latest version of MCC.
 
    Mysil
 
 
 
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RISC
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Re: MCC mapping pins 2020/11/25 16:21:51 (permalink)
2 (1)
Hi,
MCC tutorials : https://microchipdeveloper.com/mcc:start 
Regards

For support make sure to check first here : http://microchipdeveloper.com
There are hundreds of PIC, AVR, SAM...which one do YOU use ?
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_dex
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Re: MCC mapping pins 2020/11/26 01:14:02 (permalink)
4 (1)
du00000001
 
In other words: when you'd connect an internal signal to 2 different input pins: the signal from which of these 2 pins do you expect to be processed further ?

I hope you know how the OR function can be done on two EXTERNAL diodes. If not check electrical engineering basics then it will be clear, signal theory is not even needed.
 
I had simple question why it is not becoming orange. Thanks for the link but developers site i checked before posting this topic and it was not described there. Best answer have been marked, thanks to all for the clarification.
post edited by _dex - 2020/11/26 01:37:24
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du00000001
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Re: MCC mapping pins 2020/11/26 02:47:04 (permalink)
2.67 (3)
_dex
du00000001
 
In other words: when you'd connect an internal signal to 2 different input pins: the signal from which of these 2 pins do you expect to be processed further ?

I hope you know how the OR function can be done on two EXTERNAL diodes. If not check electrical engineering basics then it will be clear, signal theory is not even needed.
 
I had simple question why it is not becoming orange. Thanks for the link but developers site i checked before posting this topic and it was not described there. Best answer have been marked, thanks to all for the clarification.



I know about diode OR (which won't work w/o a pull-down resistor and quite a number of other basic logic circuits.
You seem to assume that a "pin" is just a piece of wire (but where is the resistor?), while actually a "pin" comprises at least one logic gate. And here is where your diode OR idea eventually goes poof.

PEBKAC / EBKAC / POBCAK / PICNIC (eventually see en.wikipedia.org)
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