CCS/CC3200: Unable to connect the DHT11 temperature sensor using ADC pin with CC3200

Black_Robot

Part Number: CC3200

Tool/software: Code Composer Studio

Hi,

I am trying to connect the DHT11 temperature sensor through ADC pins. I have gone through ADC demo example also.

But, I am not getting the ADC values through these pins. I know that voltage of these pins are 1.47 V. I am getting ulSample values 536092136. I don't think so the values are correct.

Can I know, what am I doing wrong here? Because, I have connected the same sensor with raspberry pi 3 and as well as Arduino.

    	PinTypeADC(PIN_58, 0xFF);
    	ADCChannelEnable(ADC_BASE, ADC_CH_1);
    	ADCTimerConfig(ADC_BASE, 2^17);
    	ADCTimerEnable(ADC_BASE);
    	ADCEnable(ADC_BASE);
    	if( ADCFIFOLvlGet(ADC_BASE, ADC_CH_1) )
    	{
    	ulSample = ADCFIFORead(ADC_BASE, ADC_CH_1);
    	ulSample = (ulSample & 0x3ffc)>>2;
    	output_voltage = (float)ulSample;
    	}

over 5 years ago

0 PM over 5 years ago

TI__Mastermind 27145 points

Hi,

I sent it to a concerned engineer. We will get back to you ASAP. Please bare with us.

Thanks,

0 Alexis Crandall20 over 5 years ago in reply to PM

TI__Genius 15590 points

Hello,

The max input voltage of the CC3200 ADC pins is 1.5V and it looks like the DHT11 I/O is 3V-5V.

Thanks,

Alexis

0 Black_Robot over 5 years ago in reply to Alexis Crandall20

Expert 1370 points

Hi Alexis Crandall20 PM,

I have decreased the voltage till 1.47 V. But, I am not getting the proper adc values as per the expectation. This is causing a huge difference in temperature.

One more thing, DHT creates the digital values. How can we say that the we are able to connect? Please find the attached data of DHT11.

DHT11-Technical-Data-Sheet-Translated-Version-1143054.pdf

        uiIndex = 0;
    	PinTypeADC(PIN_58, 0xFF);
    	ADCChannelEnable(ADC_BASE, ADC_CH_1);
    	ADCTimerConfig(ADC_BASE, 2^17);
    	ADCTimerEnable(ADC_BASE);
    	ADCEnable(ADC_BASE);
    	delay(50);
    	uint32_t i, s = 0;
    	for(i=0;i<8;i++)
    	{
    	if( ADCFIFOLvlGet(ADC_BASE, ADC_CH_1) )
    	{
    	ulSample = ADCFIFORead(ADC_BASE, ADC_CH_1);
    	ulSample = (ulSample & 0x3ffc)>>2;
    	s+=ulSample;
    	}
    }


    	s=s/i;
    	UART_PRINT("\n\r ADC average = %d",s);
    	output_voltage = (float)s*1.457/1023;
        temperature = output_voltage/10;
        UART_PRINT("\n\r temperature = %f",temperature);

0 Black_Robot over 5 years ago in reply to Black_Robot

Expert 1370 points

0 Alexis Crandall20 over 5 years ago in reply to Black_Robot

TI__Genius 15590 points

Hello,

I'm not familiar with the sensor that you're referring to, but from glancing at the datasheet and going off of what you said ("DHT creates the digital values") I'm confused why you're connecting the data pin to ADC.

It seems like you should either reference or utilize the "DHT sensor library" to interpret the data you receive from the sensor.

Thanks,

Alexis

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CCS/CC3200: Unable to connect the DHT11 temperature sensor using ADC pin with CC3200