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Sir, i am finally done writing the code for a matlab based gui, and now i am trying to test the entire circuit on a breadboard. But i am facing a serious issue, because of which i am unable to proceed. As soon as i try to power the breadboard circuit via the 5 V of the FT232 breakout board, the voltage drops to 3.6 V (which i am guessing is because of the loading effect). As a result, the microcontroller dosen't power up and i receive no response on the GUI. Can u please suggest me something to deal with this? Did u not face any such issue while testing the circuit on a breadboard or is it that i should test the circuit directly on a pcb or am i going wrong somewhere in my procedure to test a circuit with so many wires on a breadboad?
okay..so basically you are finding out the voltage actually being supplied to the circuit by doing reverse conversion of the digital value you get when you convert 3.3 V (i.e. we know on passing an analog voltage x through an ADC we get the digital value y=x*(Vref/1024) and x is 3.3 v here and y we get from the conversion and from these 2 we find out vref ) and then using that value for all the other conversions of ch1 and 2 while finiding analog values to be sketched in the gui again, right?And if i understood the above thing correctly, I have another doubt...why convert the vref on both the channels 2 & 3 when simply converting it on any one can do the job?
and sir how exactly is Vref compensating for ADC scale-factor change with variation in VDD? I am unable to understand that :/
oh yes!! i get it now :) Sir i just want to confirm one more thing, if the i/p at the channel of PGA is 5 V and the gain selected is 2, then the output will be 5 V only and not 10 V as the opamp is working on a dc voltage of 5V so that is the maximum gain it can provide, right? I just want to ensure that i wont damage my microcontroller..
oh yes!! i get it now :) Sir i just want to confirm one more thing, if the i/p at the channel of PGA is 5 V and the gain selected is 2, then the output will be 5 V only and not 10 V as the opamp is working on a dc voltage of 5V so that is the maximum output it can provide, right? I just want to ensure that i wont damage my microcontroller..
sir i have a doubt, why use a PGA when you can simply multiply the values acquired via the sampling process by any number in the gui itself? is it not like a zoom in and zoom out effect?