Using with FDC2112, 1st channel transmits only 0x40000, 0x30000 and 0x20000

[AndreiMiculita]

Hello!

Has anyone tested this on the FDC2112?

I've connected FDC2112 to an Arduino as follows:

Arduino | Level shifter | FDC2112
5V   ---| HV        LV  |--- 3.3V
3.3V ---|---------------|-'
GND  ---| GND      GND  |--- GND
A4   ---| HV1      LV1  |--- SDA
A5   ---| HV2      LV2  |--- SCL

I've run testFDC-Serial.ino:

FDC2214/examples/testFDC-Serial/testFDC-Serial.ino

Lines 48 to 68 in 8dc2368

	// bool capOk = capsense.begin(0x3, 0x4, 0x5, false); //setup first two channels, autoscan with 2 channels, deglitch at 10MHz, external oscillator
	// Start FDC2214 with 4 channels init
	bool capOk = capsense.begin(0xF, 0x6, 0x5, false); //setup all four channels, autoscan with 4 channels, deglitch at 10MHz, external oscillator
	// Start FDC2214 with 4 channels init
	// bool capOk = capsense.begin(0xF, 0x6, 0x5, true); //setup all four channels, autoscan with 4 channels, deglitch at 10MHz, internal oscillator
	if (capOk) Serial.println("Sensor OK");
	else Serial.println("Sensor Fail");
	}
	// ### Tell aplication how many chanels will be smapled in main loop
	#define CHAN_COUNT 4
	// ###
	void loop() {
	unsigned long capa[CHAN_COUNT]; // variable to store data from FDC
	for (int i = 0; i < CHAN_COUNT; i++){ // for each channel
	// ### read 28bit data
	capa[i]= capsense.getReading28(i);//
	// ### Transmit data to serial in simple format readable by SerialPlot application.
	Serial.print(capa[i]);

with the following modifications:

Uncomment

FDC2214/examples/testFDC-Serial/testFDC-Serial.ino

Line 48 in 8dc2368

// bool capOk = capsense.begin(0x3, 0x4, 0x5, false); //setup first two channels, autoscan with 2 channels, deglitch at 10MHz, external oscillator

Comment out

FDC2214/examples/testFDC-Serial/testFDC-Serial.ino

Line 50 in 8dc2368

bool capOk = capsense.begin(0xF, 0x6, 0x5, false); //setup all four channels, autoscan with 4 channels, deglitch at 10MHz, external oscillator

Change 4 to 2

FDC2214/examples/testFDC-Serial/testFDC-Serial.ino

Line 59 in 8dc2368

#define CHAN_COUNT 4

Change 28 to 16

FDC2214/examples/testFDC-Serial/testFDC-Serial.ino

Line 66 in 8dc2368

capa[i]= capsense.getReading28(i);//

Add HEX argument to print to see what's happening more clearly:

FDC2214/examples/testFDC-Serial/testFDC-Serial.ino

Line 68 in 8dc2368

Serial.print(capa[i]);

This results in the 2 channels only ever transmitting 0s. Setting intOsc to true on line 48 results in channel 0 transmitting 40000 , 30000, or 20000 (I am using this skin capacitance sensor (schematic)).

This is obviously a very low resolution, much less than the advertised 12 bits. I've tried changing the MSB address, but unfortunately all values between 0x00-0x07 are just FFFs (i.e. channel 0 transmits FFF0000 for FDC2214_DATA_CH0_MSB being set to any of 0x00-0x07).

[AndreiMiculita]

Update: after having a good look at the datasheet, a solution is to change the gain flag to 0b11:

// Set the gain flag of the moisture sensor
    uint16_t gainFlag = capsense.read16FDC(0x1C);
    Serial.println(gainFlag, HEX);
    capsense.write16FDC(0x1C, 0x3 << 9);
    gainFlag = capsense.read16FDC(0x1C);
    Serial.println(gainFlag, HEX);

This results in a 6-bit resolution, which was good enough for my application. This only applies to the FDC2112 and FDC2114.

[hussain01w]

have you used moisture click that uses FDC2112 if yes please send me the full code you used to integrate FDC 2112