I2C problem between the NXT and a Maxim ADC

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kosenhitatchi
Posts: 5
Joined: 22 Mar 2011, 10:50
Location: Lyon, France

I2C problem between the NXT and a Maxim ADC

Post by kosenhitatchi »

Hi everyone.



I'm using LabView 2009 service pack 1 an a NXT firmware 1.28 .



My goal is to command an ADC "MAX 127" from Maxim through a NXT. The DAC is connected to the NXT by the sensor plug port.



Here the doc :

http://datasheets.maxim-ic.com/en/ds/MAX127-MAX128B.pdf



I got some problems. I can not discuss with the DAC, with the NXT module "i2c communication".

I don't see any digital signal on the oscilloscope.



Could you help me to fix it.



Sincerly
Last edited by kosenhitatchi on 22 Mar 2011, 11:17, edited 1 time in total.
mightor
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Re: I2C problem between the NXT and a Maxim DAC

Post by mightor »

Did you add 82k Pull-up resistors to your circuit?

- Xander
| My Blog: I'd Rather Be Building Robots (http://botbench.com)
| RobotC 3rd Party Driver Suite: (http://rdpartyrobotcdr.sourceforge.net)
| Some people, when confronted with a problem, think, "I know, I'll use threads,"
| and then two they hav erpoblesms. (@nedbat)
kosenhitatchi
Posts: 5
Joined: 22 Mar 2011, 10:50
Location: Lyon, France

Re: I2C problem between the NXT and a Maxim ADC

Post by kosenhitatchi »

Yes, I add two 82K Pull-up resistors to my circuit. One between SDA=>Vcc, the Other SCL => Vcc.
mightor
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Re: I2C problem between the NXT and a Maxim ADC

Post by mightor »

You tested your circuit with NXC or something to that effect?

- Xander
| My Blog: I'd Rather Be Building Robots (http://botbench.com)
| RobotC 3rd Party Driver Suite: (http://rdpartyrobotcdr.sourceforge.net)
| Some people, when confronted with a problem, think, "I know, I'll use threads,"
| and then two they hav erpoblesms. (@nedbat)
kosenhitatchi
Posts: 5
Joined: 22 Mar 2011, 10:50
Location: Lyon, France

Re: I2C problem between the NXT and a Maxim ADC

Post by kosenhitatchi »

I test my system with a NI-Elvis from National Instrument. A the begining I tried to visualise the Data transfer on the I2C Bus.
mightor
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Re: I2C problem between the NXT and a Maxim ADC

Post by mightor »

I'm sorry but I am not familiar with LV, perhaps someone else can help you.

- Xander
| My Blog: I'd Rather Be Building Robots (http://botbench.com)
| RobotC 3rd Party Driver Suite: (http://rdpartyrobotcdr.sourceforge.net)
| Some people, when confronted with a problem, think, "I know, I'll use threads,"
| and then two they hav erpoblesms. (@nedbat)
kosenhitatchi
Posts: 5
Joined: 22 Mar 2011, 10:50
Location: Lyon, France

Re: I2C problem between the NXT and a Maxim ADC

Post by kosenhitatchi »

I don't think that the problem come from the electric assembly.

Here it is :
Image
Last edited by kosenhitatchi on 22 Mar 2011, 15:09, edited 1 time in total.
mightor
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Re: I2C problem between the NXT and a Maxim ADC

Post by mightor »

Your circuit (the MAX127 part of it anyway) should look like in these posts:
If it doesn't then you need to go back to the drawing board.

- Xander
| My Blog: I'd Rather Be Building Robots (http://botbench.com)
| RobotC 3rd Party Driver Suite: (http://rdpartyrobotcdr.sourceforge.net)
| Some people, when confronted with a problem, think, "I know, I'll use threads,"
| and then two they hav erpoblesms. (@nedbat)
philoo
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Re: I2C problem between the NXT and a Maxim ADC

Post by philoo »

According to your schematics, your problem is that ground connection between NXT and converter is missing!
Philo
kosenhitatchi
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Joined: 22 Mar 2011, 10:50
Location: Lyon, France

Re: I2C problem between the NXT and a Maxim ADC

Post by kosenhitatchi »

Corrected
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