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[smartwatch]

Hi,

I followed the example on https://www.youtube.com/watch?v=PJJmQwqGQDM where the mpr121 is used as a liquid level sensor. I soldered all 12 wires from the mpr121 to a copper tape. When i touch the copper plates, i see the correct values returned, however when i taped the copper plates to a plastic bottle and filled it with water, none of the sensor is activated.

Any help will be great.

Here is the config used fro the mpr121:

Code: Select all

void MPR121::begin(void){
	// STOP
	mpwrite(ELE_CFG, 0x00);
        mpwrite(RES_CF, 0X63);
        delay(10);
	// Section A
	// This group controls filtering when data is > baseline.
	mpwrite(MHD_R, 0x01);
	mpwrite(NHD_R, 0x01);
	mpwrite(NCL_R, 0x00);
	mpwrite(FDL_R, 0x00);

	// Section B
	// This group controls filtering when data is < baseline.
	mpwrite(MHD_F, 0x01);
	mpwrite(NHD_F, 0x01);
	mpwrite(NCL_F, 0xFF);
	mpwrite(FDL_F, 0x02);

	// Section C
	// This group sets touch and release thresholds for each electrode
	mpwrite(ELE0_T, TOU_THRESH);
	mpwrite(ELE0_R, REL_THRESH);
	mpwrite(ELE1_T, TOU_THRESH);
	mpwrite(ELE1_R, REL_THRESH);
	mpwrite(ELE2_T, TOU_THRESH);
	mpwrite(ELE2_R, REL_THRESH);
	mpwrite(ELE3_T, TOU_THRESH);
	mpwrite(ELE3_R, REL_THRESH);
	mpwrite(ELE4_T, TOU_THRESH);
	mpwrite(ELE4_R, REL_THRESH);
	mpwrite(ELE5_T, TOU_THRESH);
	mpwrite(ELE5_R, REL_THRESH);
	mpwrite(ELE6_T, TOU_THRESH);
	mpwrite(ELE6_R, REL_THRESH);
	mpwrite(ELE7_T, TOU_THRESH);
	mpwrite(ELE7_R, REL_THRESH);
	mpwrite(ELE8_T, TOU_THRESH);
	mpwrite(ELE8_R, REL_THRESH);
	mpwrite(ELE9_T, TOU_THRESH);
	mpwrite(ELE9_R, REL_THRESH);
	mpwrite(ELE10_T, TOU_THRESH);
	mpwrite(ELE10_R, REL_THRESH);
	mpwrite(ELE11_T, TOU_THRESH);
	mpwrite(ELE11_R, REL_THRESH);

	// Section D
	// Set the Filter Configuration
	// Set ESI2
	mpwrite(AFE1_CFG, 0x10);
	//AFE配置1 （默认=0x10）
	//	一级采样FFI:00-6次
	//	充放电电流CDC:100000 - 32uA
	mpwrite(AFE2_CFG, 0x04);
	//AFE配置2	（默认=0x24）
	//	充电时间CDT:010 - 1us
	//	二级采样SFI:00 - 4次
	//	二级采样间隔ESI:100 - 16ms


	// Section E
	// Electrode Configuration
	// Enable 6 Electrodes and set to run mode
	// Set ELE_CFG to 0x00 to return to standby mode
	mpwrite(ELE_CFG, 0x8C);	// Enables all 12 Electrodes

	//AFE配置1
	//	CL
	//	ELEPROX
	//	ELE:
	// Section F
	// Enable Auto Config and auto Reconfig
	/*mpwrite(ATO_CFG0, 0x0B);
	mpwrite(ATO_CFGU, 0xC9);	// USL = (Vdd-0.7)/vdd*256 = 0xC9 @3.3V   mpwrite(ATO_CFGL, 0x82);	// LSL = 0.65*USL = 0x82 @3.3V
	mpwrite(ATO_CFGT, 0xB5);*/	// Target = 0.9*USL = 0xB5 @3.3V
}

int MPR121::touch(void)
{
   Wire.requestFrom((uint8_t)MPR121_ADDR,(uint8_t)2);  
   uint8_t a,b;
   if(Wire.available()>=2)    // slave may send less than requested
   { 
#if defined(ARDUINO) && ARDUINO >= 100
     a = Wire.read(); // receive a byte as character
     b = Wire.read();
#else
     a = Wire.receive(); // receive a byte as character
     b = Wire.receive();
#endif
     return (a | (int)(b<<8));
   }else
   {
     return 0;
   }   
}

My Arduino code:

Code: Select all

void loop() 
{

  int var = CapaTouch.touch(); // this calls the touch method() defined above
  int num = GetSensorNumber(var);

  if(num != -1 && num != prev)
  {
    Serial.print("Num: ");
    Serial.println(num);
    prev = num;
  }  
} 

int GetSensorNumber(int var)
{ 
   if ((var&0x0800) >0) return 12;
   if ((var&0x0400) >0) return 11;
   if ((var&0x0200) >0) return 10;
   if ((var&0x0100) >0) return 9;
   if ((var&0x0080) >0) return 8;
   if ((var&0x0040) >0) return 7;
   if ((var&0x0020) >0) return 6;
   if ((var&0x0010) >0) return 5;
   if ((var&0x0008) >0) return 4;
   if ((var&0x0004) >0) return 3;
   if ((var&0x0002) >0) return 2;
   if ((var&0x0001) >0) return 1;
  return -1;
}