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AnsweredHot!Using VUSB3V3 as I/O port

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LucasBS
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2020/08/03 12:17:02 (permalink)
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Using VUSB3V3 as I/O port

I'm running out of ports for my design.

The PIC16F1455 has this useless VUSB3V3 pin, that I really wish was an I/O port

Is it possible to make it act at least as an Output pin ? Can I turn it On or Off by programming ?

I'm trying to understand this part on the datasheet, but I'm failing.
Maybe because the datasheet is not clear, or probably because I'm completely new on this... Maybe both
Can't even understand if that pin is a source or a sink of 3V3...
post edited by LucasBS - 2020/08/03 12:30:55
#1
mbrowning
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Re: Using VUSB3V3 as I/O port 2020/08/03 12:42:59 (permalink)
+1 (3)
Datasheet sections 29.6 and 29.7 seem pretty clear
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upand_at_them
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Re: Using VUSB3V3 as I/O port 2020/08/03 14:03:04 (permalink)
+1 (3)
What part of the datasheet is unclear to you?
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dan1138
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Re: Using VUSB3V3 as I/O port 2020/08/03 14:19:43 (permalink)
+2 (4)
LucasBS
Maybe because the datasheet is not clear ...



What about this is not clear:

Attached Image(s)

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Mysil
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Re: Using VUSB3V3 as I/O port 2020/08/03 14:30:59 (permalink) ☄ Helpfulby LucasBS 2020/08/03 16:13:44
+2 (2)
Hi,
If you are not developing a design to use USB communication,
then it is better to select a PIC device without USB hardware.
 
    Mysil
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upand_at_them
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Re: Using VUSB3V3 as I/O port 2020/08/03 14:31:22 (permalink)
+2 (4)
I don't think he even looked at the datasheet.
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LucasBS
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Re: Using VUSB3V3 as I/O port 2020/08/03 15:55:40 (permalink)
+1 (1)
Mysil
Hi,
If you are not developing a design to use USB communication,
then it is better to select a PIC device without USB hardware.
 
    Mysil



Hello.
Unfortunately, in some countries, we develop with what we can, not with what we want.
 
post edited by LucasBS - 2020/08/03 16:14:22
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LucasBS
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Re: Using VUSB3V3 as I/O port 2020/08/03 15:56:53 (permalink)
-2 (4)
Seriously

If you guys have nothing of constructive to add, then kindly spare your keyboard.

I don't need this kind of "help". Leave the topic unanswered and go "help" someone else.

Now, from my post:

"or probably because I'm completely new on this"
(...)
"I'm trying to understand this part on the datasheet, but I'm failing."

The hypocrite that accuses me of not reading a 400 pages datasheet didn't have the capacity to read a 6 lines post.
Well... I was humble enough and stated not once, but twice, that my understanding of the datasheet may be limited.

It surprises me the attachment to the most irrelevant part of the post...
While everyone had the capacity of saying I did not read the datasheet, no one had the capacity of answering the question: can this pin be switched on and off ?
 
To those who deserve me explaining why I find the datasheet unclear:
 
  • In table 1-2, the datasheet makes understand the pin is an input
  • In section 29.6, the datasheet makes understand the pin should be feeded with a ranged voltage
  • In section 26.2, before the note, the datasheet makes understand the voltage may vary
  • In section 26.2.2.1, third paragraph, the datasheet makes understand the pin is a voltage output. And there's a note below.
  • In table 1-3, the datasheet makes understand the pin is a voltage output
  • In table 12-2, the datasheet makes understand the pin is a voltage output
  • In figure 26-1 the datasheet makes understand the pin is a voltage output
 
Here's the datasheet I'm basing my development under. It's not up to date.
shorturl.at/ahnyQ
post edited by LucasBS - 2020/08/03 16:31:59
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LucasBS
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Re: Using VUSB3V3 as I/O port 2020/08/03 16:22:49 (permalink)
0 (2)
dan1138
LucasBS
Maybe because the datasheet is not clear ...



What about this is not clear:




 
This part you quoted is available on the latest datasheet, but not available on the datasheet I had.
Here's my datasheet to support my statement.
shorturl.at/ahnyQ
post edited by LucasBS - 2020/08/03 16:26:58
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upand_at_them
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Re: Using VUSB3V3 as I/O port 2020/08/03 16:32:30 (permalink)
+3 (3)
If you're confused by something in the datasheet then STATE what exactly you are confused by.  Don't expect people to guess or go out of their way to explain everything.  If you want help you need to make it easy for the people who are willing to help.  You do realize that nobody here is paid or obligated to help you, right?
 
It's only after someone complained that you bothered to clarify your issue.
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LucasBS
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Re: Using VUSB3V3 as I/O port 2020/08/03 17:41:39 (permalink)
-2 (2)
upand_at_them
If you're confused by something in the datasheet then STATE what exactly you are confused by.  Don't expect people to guess or go out of their way to explain everything.  If you want help you need to make it easy for the people who are willing to help.  You do realize that nobody here is paid or obligated to help you, right?
 
It's only after someone complained that you bothered to clarify your issue.



Whole point is, forgive the arrogance (as I get nothing with being humble): I didn't ask to clarify my confusion.

 
I asked if the pin could be controlled by a register. That's all. There's no "guessing" here. It's there in the second line.
 
The part where I did not understand the datasheet is a //COMMENT.
I shouldn't have to "bother to clarify an issue" that I didn't have in the first place, but everyone decided to center the thread on that point.
 
I realize everyone here are voluntary, but that does't give no one the right to abduct and troll a thread. I hope I get to help someone too some day. I'm not gonna use euphemisms here: God forbid me to ever act arrogantly like you guys on this thread.
post edited by LucasBS - 2020/08/03 17:45:47
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dan1138
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Re: Using VUSB3V3 as I/O port 2020/08/03 19:41:49 (permalink)
+2 (2)
LucasBS
dan1138
LucasBS
Maybe because the datasheet is not clear ...

What about this is not clear:

This part you quoted is available on the latest datasheet, but not available on the datasheet I had.
Here's my datasheet to support my statement.
shorturl.at/ahnyQ <--- This is a broken URL

You are "claiming" to have the revision A data sheet for the PIC16F1455 as your current documentation.
 
That data sheet was published on June of 2012 and replaced in March of 2014. There have been no other updates.
 
That could be the case, but seems unlikely.
 
It is more likely you have been discover after posting something foolish. It would be wiser to admit to that even if you think you are in the right. I suggest this because, based on your present attitude, insisting now would be seen as compounding foolishness with stupidity, and anything you would offer to support your claim would be ignored.
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LucasBS
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Re: Using VUSB3V3 as I/O port 2020/08/03 20:28:46 (permalink)
-2 (2)
dan1138

I didn't understand a thing you wrote
 
But here's the fixed link:
https://1drv.ms/b/s!AilzH...xPMOu06NcKl82?e=hATwXS
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LucasBS
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Re: Using VUSB3V3 as I/O port 2020/08/03 20:33:00 (permalink)
0 (2)
Now, anyone: Is there any register bit that can be used to turn on/off that VUSB3V3 pin ? As in, toggle between 3V3 (source mode) Vs. 0V (high impedance mode), or even Sink mode
post edited by LucasBS - 2020/08/03 20:56:24
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dan1138
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Re: Using VUSB3V3 as I/O port 2020/08/03 20:57:28 (permalink) ☼ Best Answerby LucasBS 2020/08/04 04:02:52
+2 (2)
LucasBS
I didn't understand a thing you wrote



Ok, we can both agree that my post holds no meaning.
 
So you are using the revision "A' data sheet for the PIC16F1455. The information in that data sheet describing VUSB3V3 is about the same as that found in the in the current data sheet. It is still a power pin and is an input for the PIC16LF1455 device and a node that requires an external decoupling capacitor for the PIC16F1455 device. No other uses are described for this pin.
 
I have taken a thorough look through both available data sheets and found no mention of any way that the VUSB3V3 LDO voltage regulator can be controlled by the PIC16F1455. Note that the PIC16LF1455 does not have an LDO at all.
 
It is possible that this LDO may be turned off when the USB is disabled but this would be something you would need to test. In all cases the VUSB3V3 is a power supply for the on-chip USB transceiver circuitry so the only way 3.3 volts would not be required on this pin would be when the USB interface is not in use and not connected to a USB host.
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LucasBS
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Re: Using VUSB3V3 as I/O port 2020/08/04 04:08:01 (permalink)
0
Thank you

Bad news at first, but maybe that idea of turning off USB completely might work. I just need a "one shot" pulse during the whole functioning of my machine anyway. This could work !

The part of the datasheet that teaches how to manipulate USB is clear enough for my understanding

Thank you again.
post edited by LucasBS - 2020/08/04 04:10:12
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