Problem using analog PIN

Comments

• wjcroft Mount Shasta, CA

  January 2017

  Davide, hi. I assume you've seen the external trigger tutorial,
  
  http://docs.openbci.com/Tutorials/06-External_Trigger_32bit_Example
  
  But that's not using analog pin. @yttuncel has a code snippet here using analog, he may chime in,
  
  http://openbci.com/forum/index.php?p=/discussion/comment/5075/#Comment_5075
  
  
• davide_93

  January 2017

  @wjcroft Thank you for your reply!

  
  

  Yes, I've read the external trigger tutorial, but as you say it's a digital pin and not analog pin. 

  
  

  It seems to me that the value stored in OpenBCI.auxData the first time the loop is executed then doesn't change.

  
  

  @yttuncel is using the same code as mine:

  
  

     //Analog Trigger Read

        analogValue = analogRead(A7);

        board.auxData[1] = analogValue;

  
  

  and in the .txt file posted the value of the second column in the auxValues is always 0.0..
  

  
  

  Do you think that upgrading the board firmware to v2 will help? 
• wjcroft Mount Shasta, CA

  January 2017

  Let's ask AJ Keller @pushtheworld, the V2 dev.

  
  
• pushtheworld

  January 2017 edited January 2017

  You can see an example of an analog sensor with V2 firmware. Please note this requires updating all three uC's if you have V1 firmware!

  
  

  https://github.com/OpenBCI/OpenBCI_32bit_Library/blob/master/examples/BoardWithAnalogSensor/BoardWithAnalogSensor.ino
  
• davide_93

  January 2017

  Thanks @pushtheworld, I'll try to update the firmware on all the uC and see if it works!
• davide_93

  January 2017

  Hi, 

  I uploaded the firmware on all the three microcontrollers. 

  
  

  When I use the "defaultBoard" firmware, everything is working fine and I can read and visualize all the data in the correct way, both with OpenBCI_GUI and with the software that I wrote.

  
  

  But when I use the code "BoardWithAnalogSensor" this is no longer true: even with the OpenBCI_GUI it is not possible for me to read any data.. I didn't change anything in the code and I don't why this is happening

  
  

  Thanks again
• pushtheworld

  January 2017 edited January 2017

  @davide_93 ;I'm glad you were able to read from it!

  
  

  Need to update a line in the processing to read the different stop byte. The idea is you are telling the Driver NOT to scale the last 6 bytes. You can see a concrete example in how to properly do this in the node,js repo sample packet properties. 

  
  

  I just updated it and PR'd into https://github.com/OpenBCI/OpenBCI_GUI/blob/master/OpenBCI_GUI/HardwareSync.pde#L892

  
  

  You can check it out and you won't have that problem. There is a build coming for it soon!
• davide_93

  January 2017

  Thank you @pushtheworld for your reply.
  
  With the default board firmware I could read only the channels data, I tried to read the analog sensor by disabling the useAccel and writing
  board.auxData[0] = analogRead(A7)
  but it didn't work.
  
  What I noticed is that the value provided at the first sample is correct, but then it is no longer updated..
  
  Then I tried to the firmware with the analog sensor, but I didn't work due to the problem that you explained me.
  
  I really don't know what to do
  
  
  
  
  
• pushtheworld

  January 2017

  Download the OpenBCI_GUI (repo | .zip) and processing 3 and run that gui! I just updated the master copy for you! 
• pushtheworld

  January 2017 edited January 2017

  The processing GUI only really supports the default board, once you start changing the firmware, the assumption is you are writing custom code probably for doing work or analysis on. You should try using the node (you can get streaming in a couple lines), and if you, for example, need to pipe into python, check out the full duplex node to python example. We (@pushtheworld) use the different stop bytes to do wireless time syncing for out new openbci app thinker.
• davide_93

  January 2017

  Hi @pushtheworld,

  
  

  thank you very much for your help! With the new version of the OpenBCI GUI I was able to correctly read the data of my analog sensor. 

  
  

  I'm writing my custom software with Processing to read the data from the OpenBCI: right now I can correctly read the channels data, but I'm still having problems with the analog sensor, probably because I need to adjust my code to the v2 firmware. 
• davide_93

  January 2017

  I tried to fix my code, but it is still impossible for me to see the auxValue changing: it has always the same value even though I know that it is changing (and with the OpenBCI GUI I can see it changing in the .txt file). 

  
  

  This is the code that I wrote for my Processing application (I know that it is very simple and probably not well-written): now, for sure the problem is related to it, even though I cannot figure out where it is.

  I use as "end Byte" for the data packet the byte 0xC1 as stated in OpenBCI_DataFormat.