Hello everyone~

[kayla_tuyu_china 0]

hello everyone~ I am a new here. Now I use the c2000 and I always face some problem, so hope you can solve my problem and hope you can understand me through my bad English.

 

thanks for Trey's help and I know something about energia for c2000.

 

And a question here.

I use ccs5.0.3 and some days ago I upload the program Example_2802xAdcSoc. Then I debug it and use the tool--graph to get the wave shape. But it didn't work well.

 

 

That is the wave shape I got. [50HZ sin ware]

[TI_Trey 38]

Kayla,

 

It looks like it is working to me.  The 50Hz mains power is capcitively coupling into the ADC input, therefore you see a 50Hz sine wave in the graph window.  The noise on the sin wave is due to the fact that this signal isn't really being driven with any strength.  If you were to pick up the signal with an antenna and then buffer it with an opamp before sampling, I would venture to say that the sin wave would be much more ideal.

[kayla_tuyu_china 0]

Trey

 

Very thank you ~ I'm sooooooo happy you always answer me so particularly. And do I set the graph properties all righ?

 

And the highest rate I can use c2000 to get is?

 

I will add an antenna and try again.

[TI_Trey 38]

The graph properties look ok.  An antenna won't really help much on its own.  The problem here is the strength with which the signal is driven into the ADC.  To accurately sample a signal the ADC needs to be driven with some amount of current.  With your current setup, current must capacitively couple from the mains power in the walls through the air into the board.  Only a very small amount of current will reach the ADC.  If you insert a buffer (an opamp would be perfect), its input will have a high impedance and will be able to pick up the 50Hz signal and its output will have a low impedance which is much more suitable for driving the ADC input.

[TI_Trey 38]

I forgot something...

 

This device has an errata for the ADC.  Basically the first conversion in a group of conversion can give bad data.  Whenever you do a sample, you should do a dummy sample with another SOC before sampling the desired signal.  Look at how this is done in the adc_soc example.

 

The errata is here:

http://www.ti.com/lit/er/sprz292j/sprz292j.pdf