Digital Out high state on power up - Netduino Plus 2 (and Netduino Plus 1) - Netduino Forums
   
Netduino home hardware projects downloads community

Jump to content


The Netduino forums have been replaced by new forums at community.wildernesslabs.co. This site has been preserved for archival purposes only and the ability to make new accounts or posts has been turned off.
Photo

Digital Out high state on power up

Started by Sharktear, Feb 25 2013 07:11 PM

  • Please log in to reply
5 replies to this topic

#1 Sharktear

Sharktear

    Member

  • Members
  • PipPip
  • 11 posts

Posted 25 February 2013 - 07:11 PM

Hi all,

has anything changed with the 4.2 firmware on netduino plus about the high state of the digital out pins?

I have verified that the problem of the high state of the output pins still exist, so when the device start for a few seconds the output pins have an high state. Unlike before, however, the high state does not trigger a relay, as if it hadn't enough current to trigger the threshold of the transistor that drives the relay. I remember that in my previous test (several months ago), the relay was triggering and in fact I searched for a possible solutions to the problem. What has changed?


#2 Arron Chapman

Arron Chapman

    Advanced Member

  • Members
  • PipPipPip
  • 289 posts
  • LocationOregon, USA

Posted 25 February 2013 - 08:49 PM

This is an issue caused by the microcontroller itself, and it can't be fixed via a firmware update.  The simplest solution is to simply add a pulldown resistor on the I/O pin.


When you talk EE use small words, I'm just a Software Developer :)
My Blog/Site and Everything Else

If my post helped you please consider pressing the "Like This" button in the bottom right-hand corner.

 

Oh my. So many things, so little money!!

 

#3 Sharktear

Sharktear

    Member

  • Members
  • PipPip
  • 11 posts

Posted 25 February 2013 - 08:58 PM

Yes, I know that. The strange thing is that now the high state on power up does not trigger a relè connected to a digital pin, but months ago this happened.


#4 Paul Newton

Paul Newton

    Advanced Member

  • Members
  • PipPipPip
  • 724 posts
  • LocationBerkshire, UK

Posted 26 February 2013 - 07:13 AM

The only thing that comes to mind is whether you are using different pins to the ones you had before.

Some of the digital pins have slightly higher curent drive, and these will have different properties to the other digital pins.

Also two of the analogue pins do not have the pull high at power on behaviour.

 

Paul


#5 Sharktear

Sharktear

    Member

  • Members
  • PipPip
  • 11 posts

Posted 26 February 2013 - 08:58 AM

Yes I think it's the probably cause. Now I'm using the digital pin D6. From the netduino plus pinout I see that it can supply 8mA and probably this current on power up is more lower (when I set the pin high from my code it correctly trigger the relay). Maybe in my past tests I used another pin that supply a 16mA max current and on power up the current of this pin was much higher.

I'll try some other tests using other digital pin to see if I can reproduce the behaviour.

What are the two analog pin that do not have the pull high at power on behaviour? They can be used in digital output mode?

Thanks


#6 Paul Newton

Paul Newton

    Advanced Member

  • Members
  • PipPipPip
  • 724 posts
  • LocationBerkshire, UK

Posted 26 February 2013 - 07:08 PM

I was going to say A4 and A5, but I don't have any test equipment to hand to verify this.

I think I tested this a while ago, but can't find any proof I did the test.

 - First one to prove me right or wrong wins a smiley.

 

The data sheet for the Plus 1 ARM AT91SAM7X512 data sheet section 6.5 PIO Controller Lines, indicates that the AD4-AD7 inputs do not have programmable pull up resistors.

 

BUT, A4 and A5 lines are connected to AD4 and AD5 or PA10 and PA11 via a MUX (the mux allows the pins to also be used for I2C).

The problem is that I can't tell from the data sheet if the MUX connects them to the analogue inputs or to the PA10 and PA11 pins at power on.

 

If the MUX connects them to AD4 and AD5, then they should not be pulled high.

If the MUX connects them to PA10 and PA11, then they will be pulled high.

 

Anyone want to prove which it is.....

 

I have run a quick test and proven that A4 and A5 can be used as digital IO (probably because the firmware switches the MUX to PA10 and PA11).

 

Paul


Back to Netduino Plus 2 (and Netduino Plus 1)


0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users

  1. Netduino Forums
  2. → Hardware
  3. → Netduino Plus 2 (and Netduino Plus 1)
  4. Privacy Policy
home    hardware    projects    downloads    community    where to buy    contact Copyright © 2016 Wilderness Labs Inc.  |  Legal   |   CC BY-SA
This webpage is licensed under a Creative Commons Attribution-ShareAlike License.