I2C clock issue on reset

nichlas21 · July 22, 2023, 7:54pm

Hi.
I’m pretty new to the Arduino Stuff and bought myself the UNO R4 minima for an electronics project. Yay! I have co-workers who are quite experts in electronics but I am starting to have hardware concerns for this specific problem.

I have tested this on a couple of I2C sensors/devices and will present the simplest and quite “standard” one. The LCD 1602.

It is this setup

Using the I2C scanner code: https://playground.arduino.cc/Main/I2cScanner/

When I power on my board using USB or I press the reset button, the code doesn’t work. If I disconnect the SCL (both when setting up A4/A5 or the SCL/SDA pins) and reconnect it, the code instantly works and I receive the correct address. If I power off the board or press the reset button. The code returns “no address found” until I do the disconnect/reconnect thing.

I have tried with and without pull-up resistors (10kOhm) on the breadboard without change. The same with some differential pressure sensors.

I don’t understand how this standard LCD1602/I2C tutorial kinda stuff shouldn’t work.

Could this be a hardware bug?? Any ideas?

MaximoEsfuerzo · July 22, 2023, 8:41pm

The display is powered by 5V not 3.3V

error

Merlin513 · July 22, 2023, 9:43pm

I have been running into the same issue, i.e, having cycle the power to the board, using a slightly different scanner sketch. It may be related to the current draw on the pins - but I have several I2C devices hanging off the different Wire busses.

KurtE · July 22, 2023, 10:44pm

You mean something like this:

Although I have also run into it without any thing hung on the board.
And we are using a mucked up version of the scanner, which on the Wifi board
is scanning all 3 Wire busses.

// --------------------------------------
// i2c_scanner
// http://playground.arduino.cc/Main/I2cScanner
//
// Version 1
//    This program (or code that looks like it)
//    can be found in many places.
//    For example on the Arduino.cc forum.
//    The original author is not know.
// Version 2, Juni 2012, Using Arduino 1.0.1
//     Adapted to be as simple as possible by Arduino.cc user Krodal
// Version 3, Feb 26  2013
//    V3 by louarnold
// Version 4, March 3, 2013, Using Arduino 1.0.3
//    by Arduino.cc user Krodal.
//    Changes by louarnold removed.
//    Scanning addresses changed from 0...127 to 1...119,
//    according to the i2c scanner by Nick Gammon
//    http://www.gammon.com.au/forum/?id=10896
// Version 5, March 28, 2013
//    As version 4, but address scans now to 127.
//    A sensor seems to use address 120.
// Version 6, November 27, 2015.
//    Added waiting for the Leonardo serial communication.
//
//
// This sketch tests the standard 7-bit addresses
// Devices with higher bit address might not be seen properly.
//
// --------------------------------------
#include <Wire.h>

#define WIRE2_SCL_PIN 0
#define WIRE2_SDA_PIN 1
TwoWire Wire2(WIRE2_SCL_PIN, WIRE2_SDA_PIN);

typedef struct {
  TwoWire *_wire;
  const char *wire_name;
} wire_list_t;

wire_list_t wireList[] = {
  { &Wire, "Wire" }, { &Wire1, "Wire1" }, { &Wire2, "Wire2" }
};

const uint8_t wirelist_count = sizeof(wireList) / sizeof(wireList[0]);


void setup() {
  // uncomment these to use alternate pins
  //Wire.setSCL(16);
  //Wire.setSDA(17);
  for (uint8_t wirelist_index = 0; wirelist_index < wirelist_count; wirelist_index++) {
    wireList[wirelist_index]._wire->begin();
  }
  Serial.begin(115200);
  while (!Serial)
    ;  // Leonardo: wait for serial monitor
  Serial.println(F("\nI2C Scanner"));
}


void loop() {
  byte error, address;
  int nDevices;

  for (uint8_t wirelist_index = 0; wirelist_index < wirelist_count; wirelist_index++) {
    Serial.print(F("Scanning("));
    Serial.print(wireList[wirelist_index].wire_name);
    Serial.println(F(")..."));
    nDevices = 0;
    for (address = 1; address < 127; address++) {
      // The i2c_scanner uses the return value of
      // the Write.endTransmisstion to see if
      // a device did acknowledge to the address.
      wireList[wirelist_index]._wire->beginTransmission(address);
      error = wireList[wirelist_index]._wire->endTransmission();

      if (error == 0) {
        Serial.print(F("Device found at address 0x"));
        if (address < 16) {
          Serial.print("0");
        }
        Serial.print(address, HEX);
        Serial.print("  (");
        printKnownChips(address);
        Serial.println(")");

        nDevices++;
      } else if (error == 4) {
        Serial.print(F("Unknown error at address 0x"));
        if (address < 16) {
          Serial.print("0");
        }
        Serial.print(address, HEX);
      }
    }
    if (nDevices == 0) {
      Serial.println(F("No I2C devices found\n"));
    } else {
      Serial.println(F("done\n"));
    }
  }
  delay(5000);  // wait 5 seconds for next scan
}


void printKnownChips(byte address) {
  // Is this list missing part numbers for chips you use?
  // Please suggest additions here:
  // https://github.com/PaulStoffregen/Wire/issues/new
  switch (address) {
    case 0x00: Serial.print(F("AS3935")); break;
    case 0x01: Serial.print(F("AS3935")); break;
    case 0x02: Serial.print(F("AS3935")); break;
    case 0x03: Serial.print(F("AS3935")); break;
    case 0x0A: Serial.print(F("SGTL5000")); break;  // MCLK required
    case 0x0B: Serial.print(F("SMBusBattery?")); break;
    case 0x0C: Serial.print(F("AK8963")); break;
    case 0x10: Serial.print(F("CS4272")); break;
    case 0x11: Serial.print(F("Si4713")); break;
    case 0x13: Serial.print(F("VCNL4000,AK4558")); break;
    case 0x18: Serial.print(F("LIS331DLH")); break;
    case 0x19: Serial.print(F("LSM303,LIS331DLH")); break;
    case 0x1A: Serial.print(F("WM8731")); break;
    case 0x1C: Serial.print(F("LIS3MDL")); break;
    case 0x1D: Serial.print(F("LSM303D,LSM9DS0,ADXL345,MMA7455L,LSM9DS1,LIS3DSH")); break;
    case 0x1E: Serial.print(F("LSM303D,HMC5883L,FXOS8700,LIS3DSH")); break;
    case 0x20: Serial.print(F("MCP23017,MCP23008,PCF8574,FXAS21002,SoilMoisture")); break;
    case 0x21: Serial.print(F("MCP23017,MCP23008,PCF8574")); break;
    case 0x22: Serial.print(F("MCP23017,MCP23008,PCF8574")); break;
    case 0x23: Serial.print(F("MCP23017,MCP23008,PCF8574")); break;
    case 0x24: Serial.print(F("MCP23017,MCP23008,PCF8574")); break;
    case 0x25: Serial.print(F("MCP23017,MCP23008,PCF8574")); break;
    case 0x26: Serial.print(F("MCP23017,MCP23008,PCF8574")); break;
    case 0x27: Serial.print(F("MCP23017,MCP23008,PCF8574,LCD16x2,DigoleDisplay")); break;
    case 0x28: Serial.print(F("BNO055,EM7180,CAP1188")); break;
    case 0x29: Serial.print(F("TSL2561,VL6180,TSL2561,TSL2591,BNO055,CAP1188")); break;
    case 0x2A: Serial.print(F("SGTL5000,CAP1188")); break;
    case 0x2B: Serial.print(F("CAP1188")); break;
    case 0x2C: Serial.print(F("MCP44XX ePot")); break;
    case 0x2D: Serial.print(F("MCP44XX ePot")); break;
    case 0x2E: Serial.print(F("MCP44XX ePot")); break;
    case 0x2F: Serial.print(F("MCP44XX ePot")); break;
    case 0x33: Serial.print(F("MAX11614,MAX11615")); break;
    case 0x34: Serial.print(F("MAX11612,MAX11613")); break;
    case 0x35: Serial.print(F("MAX11616,MAX11617")); break;
    case 0x38: Serial.print(F("RA8875,FT6206,MAX98390")); break;
    case 0x39: Serial.print(F("TSL2561, APDS9960")); break;
    case 0x3C: Serial.print(F("SSD1306,DigisparkOLED")); break;
    case 0x3D: Serial.print(F("SSD1306")); break;
    case 0x40: Serial.print(F("PCA9685,Si7021")); break;
    case 0x41: Serial.print(F("STMPE610,PCA9685")); break;
    case 0x42: Serial.print(F("PCA9685")); break;
    case 0x43: Serial.print(F("PCA9685")); break;
    case 0x44: Serial.print(F("PCA9685, SHT3X")); break;
    case 0x45: Serial.print(F("PCA9685, SHT3X")); break;
    case 0x46: Serial.print(F("PCA9685")); break;
    case 0x47: Serial.print(F("PCA9685")); break;
    case 0x48: Serial.print(F("ADS1115,PN532,TMP102,LM75,PCF8591")); break;
    case 0x49: Serial.print(F("ADS1115,TSL2561,PCF8591")); break;
    case 0x4A: Serial.print(F("ADS1115")); break;
    case 0x4B: Serial.print(F("ADS1115,TMP102,BNO080")); break;
    case 0x50: Serial.print(F("EEPROM,FRAM")); break;
    case 0x51: Serial.print(F("EEPROM")); break;
    case 0x52: Serial.print(F("Nunchuk,EEPROM")); break;
    case 0x53: Serial.print(F("ADXL345,EEPROM")); break;
    case 0x54: Serial.print(F("EEPROM")); break;
    case 0x55: Serial.print(F("EEPROM")); break;
    case 0x56: Serial.print(F("EEPROM")); break;
    case 0x57: Serial.print(F("EEPROM")); break;
    case 0x58: Serial.print(F("TPA2016,MAX21100")); break;
    case 0x5A: Serial.print(F("MPR121")); break;
    case 0x60: Serial.print(F("MPL3115,MCP4725,MCP4728,TEA5767,Si5351")); break;
    case 0x61: Serial.print(F("MCP4725,AtlasEzoDO")); break;
    case 0x62: Serial.print(F("LidarLite,MCP4725,AtlasEzoORP")); break;
    case 0x63: Serial.print(F("MCP4725,AtlasEzoPH")); break;
    case 0x64: Serial.print(F("AtlasEzoEC")); break;
    case 0x66: Serial.print(F("AtlasEzoRTD")); break;
    case 0x68: Serial.print(F("DS1307,DS3231,MPU6050,MPU9050,MPU9250,ITG3200,ITG3701,LSM9DS0,L3G4200D")); break;
    case 0x69: Serial.print(F("MPU6050,MPU9050,MPU9250,ITG3701,L3G4200D")); break;
    case 0x6A: Serial.print(F("LSM9DS1")); break;
    case 0x6B: Serial.print(F("LSM9DS0")); break;
    case 0x70: Serial.print(F("HT16K33")); break;
    case 0x71: Serial.print(F("SFE7SEG,HT16K33")); break;
    case 0x72: Serial.print(F("HT16K33")); break;
    case 0x73: Serial.print(F("HT16K33")); break;
    case 0x76: Serial.print(F("MS5607,MS5611,MS5637,BMP280")); break;
    case 0x77: Serial.print(F("BMP085,BMA180,BMP280,MS5611")); break;
    case 0x7C: Serial.print(F("FRAM_ID")); break;
    default: Serial.print(F("unknown chip"));
  }
}

Note: I have explictily created Wire2 using pins 0 and 1.

I should probably try it on the Minima board as well, but would only have 2 Wire objects.

Merlin513 · July 23, 2023, 12:09am

Yep - exactly like that.

nichlas21 · July 23, 2023, 3:43am

That doesn’t change anything. I know I could change it, but the SDP sensors run off 3.3V. I actually started on external 5V and ended troubleshooting all the way back to the onboard power source.

But I like to know the explanation of how the reconnection thing then would make the sketch work? because it doesn’t in my case

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I2C clock issue on reset

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