Nitrogen Dioxide Sensor and the LMP9100

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#1
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Hi All

 

I am using having some issue reading a  Nitrogen Dioxide Sensor(http://www.ddscientific.com/uploads/5/7/1/3/57136893/gs_4no2_datasheet___.pdf) with Texas Instruments LMP9100

 

My Register settings are the following:

LOCK (0x01) = 0x00

TIACN(0x10) = 0x14

REFCN(0x11) = 0xE0

REFCN(0x12) = 0x03

 

I am getting a continuous 3.28V output, even if i am indoors or outdoors.

 

My application is a battery application, therefore i am powering the device, setting is registers and then reading voltage. 

 

Does this seem correct?

 

Regards

 

DJ

 

 

Thanks

Regards

DJ

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djoshi wrote:
REFCN(0x11) = 0xE0

This does not seem right to me, try it with default values and see what you get.

 

Jim

 

 

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djoshi wrote:

My Register settings are the following:

LOCK (0x01) = 0x00

TIACN(0x10) = 0x14

REFCN(0x11) = 0xE0

REFCN(0x12) = 0x03

Take a step back from there. The d/s says it is I2C. What have you done to even prove the basic operation of the I2C interface - you could just call i2c_write(0x14) or whatever in your code but how do you know the device is even listening?

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Ok, will set it to the defaults.

 

Should i need to wait a certain duration after powering the PCB or device.

Thanks

Regards

DJ

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I am have read them back, and if i was to set my device to read the internal temperature, the results are accurate. This proves the i2c code is correct.

 

Thanks

Regards

DJ

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djoshi wrote:
if i was to set my device to read the internal temperature, the results are accurate. This proves the i2c code is correct.

Very good test.

You should try to contact the sensor manufacturer or their distributors representative for recommendations on proper settings to get good reading on this sensor.

 

Jim

PS wish I had seen that TI sensor interface when I was working on an O3 sensor project a while back!

 

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Might be a silly questions,, the sensor has a sticker on the top, maybe a filter...

 

Should these be removed?

Thanks

Regards

DJ

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The manufacturer is in the UK - just make a phone call. Ask them how to do a simple test. Usually with gas sensors you can buy cans of test gas.