cancel
Showing results for 
Search instead for 
Did you mean: 

PSoC 5, 3 & 1 MCU

Anonymous
Not applicable

Hi, my signal is 54 KHz ultrasonic signal from transducer, based on Nyquist theorem I need two times the transducer central frequency but I need more than this for my project, between 8 and 10 times the central frequency, from the ADC SAR datasheet I have read that I need to place an external capacitor,the voltage levels  of the ultrasonic signal are in the scale of milivolts ( 250 mV P-P), but actually I don´t know if the signal must be placed like an external terminal in analog pin or like a variable voltage source.   Thank you very much for the answers, I'm new with the Psoc devices and want to learn a lot from you.   

0 Likes
4 Replies
RaAl_264636
Contributor II

Hi Jhesus,

not sure if I understand your question correct. You ask if you have to place either an ADC and a analog pin component vs. a voltage source component? If you have a external sensor with analog output, you've to use ADC and analog pin component.

Regards

Anonymous
Not applicable

Yes this is one part of the answer, I just place an analog pin in the input of the ADC, this is the same signal wich is the analog output from the transducer. Thank you for your attention, but I have been confused with the SAR ADC, because I have a variable signal between negative and positive values, I don't know actually what input range is the correct to configure the SAR ADC, I supose this must be differential...

here is a picture of my signal, I need sample and send it to PC through serial protocol:

0 Likes
RaAl_264636
Contributor II

Hi Jhesus,

the input signal must be between VSSA and VDDA. If the signal is not within this range, then use a combination of series capacitor and two resistors between GND and analog supply voltage. This will remove any DC offset from the signal, and shift the signal to VDDA/2.

Regards

0 Likes
EvPa_264126
Valued Contributor II

Possible variant for start.

0 Likes