3 Replies Latest reply on Sep 28, 2014 6:50 PM by pulled_pork

    Galileo Gen 1 vs Gen 2 problem



      G1 = Galileo Gen 1 - When the G1 board is powered up and goes thru the booting sequence from the SD card (Software and firmware for 1.0.0 ver) – Scope picture shows a large saw tooth waveform on the A1 pin connected to the Vout of the LM35 temp sensor. 


      After the G1 boots completely and starts to run the sketch program to read the temp sensor on input A1, the large saw tooth waveform (350mVpp,20uS) disappears.


      G1 board proceeds and everything runs fine with a stable A1 or LM35 Vout. 

      The large saw tooth waveform at A1 during the startup, goes away once the sketch starts.

      I have a total of (3) G1 boards and they all have a stable A1 input (LM35) output, when the sketch is running after booting.   


      G2 = Galileo Gen 2 board - I purchased a new G2 earlier this week.


      I created the Linux SD card for booting the OS from SD.

      I connected the same sensor and LCD shield to the Gal Gen 2 board. 

      Software and firmware for 1.0.2 ver.


      Temperature circuit became unstable on the G2 and the values fluctuate between 10 to 15 degrees on the LCD display.

      I used my scope on the G2 A1 pin and compared it to the working G1 A1 pin. 


      On the G2, the ADC IO must be causing the waveform or saw tooth, I am pretty sure it’s not from the LM35 and the G1 board does not have this problem.


      On the G2 the saw tooth remains after the board boots up.


      The temperature has 220mVpp, 40uS waveform. Only difference is the G2 board. 

      The G2 must require some special setup of the A0-A5 ADC ports? Possibly setup the ports thru Linux commands ?  Or Library update/missing library ?

      Works fine on the G1, shouldn't my code work regardless if I am using the Gen1 or Gen2 Galileo?



      I attached videos of the G1 that works and the G2 that does not. 


      #1 - Gal Gen1 in booting sequence shows A1 with problematic waveform on A1 that will eventually go away once the user sketch is started.




      #2 - Gal Gen1 after booting sequence shows A1 problematic waveform has gone away and DC millilvolt value from LM35 is read at the A1 input.




      #3 - 4 -  Gal Gen2 in booting sequence shows A1 with problematic waveform on A1 that will not eventually go away and causes severe noise while reading temp on A1.

                    Gal Gen2 after booting sequence shows A1 with problematic waveform on A1 that did not go away as it did on the Gal Gen 1 board.



      I also moved the A1 to A2 on the Gal Gen 2 to see if it was just A1 problem, but it followed to A2 ADC input.

      A0 has a photocell attached, but I don’t see any problems with the scope, looks like standard DC voltage divider with photocell and small amount of 60Hz stuff from indoor lighting.