Activity Forums Questions & Troubleshooting Hardware [MAXI Automation] Analog IN and internal 5V supply deviation Reply To: [MAXI Automation] Analog IN and internal 5V supply deviation

  • Friedl_AP

    Member
    March 17, 2021 at 4:25 pm

    Dear Jarda!

    I’ve now tried the following:

    1. Switched ADC to external reference as first command of setup()
    2. After loading the code I switched on a lab supply (4.500 V) connected to GND/VREF on X2
    3. AI12 is driven by another lab supply with 4.500 V (GND=screw terminal of Controllino, measured versus GND of Controllino)
    4. ADC value: 602 (expected (1024/2-1)=511)
    5. reduce VREF till ADC value gives 1023
    6. VREF measured: 2.653 V (expected 4.500V/2 = 2.25V)

    The internal reference is off and connecting an external reference does not really work either.

    Code:

    #include <Controllino.h>

    /*
    * CONTROLLINO MAXI AUTOMATION - using analog VREF input
    *
    * Reads out converted analog values from a screw terminal input AI12
    * of CONTROLLINO using VREF on X2 as reference.
    *
    * ------------------------
    * 24V ---------o--------------| 24V |
    * external | | |
    * supply | | |
    * -------------- | CONTROLLINO MAXI |
    * | Lab Supply |--------| AI12 | ---------------
    * | 4.500V | | X2-VREF |--------| Lab Supply |
    * -------------- | | | 4.500V |
    * | | | ---------------
    * | | | |
    * GND ---------o--------------| GND X2-GND |---------------o
    * ------------------------
    * remark: AI12 = internal divider 2:1
    * ATTENTION: Only switch on the lab supply on VREF after you've downloaded the code the first time!
    */

    void setup() {
    analogReference(EXTERNAL);
    pinMode(CONTROLLINO_AI12, INPUT);
    Serial.begin(115200);
    delay(300);
    }

    void loop() {
    int val = analogRead(CONTROLLINO_AI12);
    Serial.print(F("raw value: ")); Serial.println(val);
    delay(100);
    }

    • This reply was modified 1 month, 3 weeks ago by  Friedl_AP. Reason: stray DIV tags removed