Hi, I added to the input of arduino due a 3.3v protection zener according to the attached diagram, giving an input on CURR of 3.3v i or I read at the input of the arduino door 0.73 v, the configuration I adopted derives from other schemes taken from the web, please can someone help me where am I wrong? thanks Jacob.
Your schematic is a big help. Normally ground is down and power is up. Input is from the left and the output to the right. I have no clue what A4 is, is it a choke? Also the processor will not measure current but it will measure voltage. At this point I would say change the 330 Ohm resistor to 2K to 10K and input where A4 connects to the resistor. You can remove A4 from what I know at this point. More information always helps such as links to technical information on hardware parts. The schematic saved you about 10 pages of writing a word problem.
Thanks for the answer: I intend to read the current that draws a 1Kw radio transmitter, I use an ACS756: Fully Integrated, Hall Effect-Based Linear Current Sensor IC with 3 kVRMS Voltage Isolation and a Low-Resistance Current Conductor, I read the output value with amp = map (analogRead (A4), 512,1023,0,625); this code comes from a 5 volt pin arduino. I want to transform this code to use it with arduino due, as arduino due has ports at 3.3v, I would like to protect the arduino due from a voltage greater than 3.3v, which it usually does not reach. I think this code, amp = map (analogRead (A4), 512,1023,0,625); , it can also go well with arduino due, The sensor has an output from 2.5v = 0 Ampere up to 5v 50Ampere. But the thing I do not understand is why with the addition of the zener, with voltages slightly higher than 3v, the diagram I have attached, at the entrance of the arduino door (A45) gives me back just 0.70v and not 3v. ?
This was the question I asked on the forum,I add that I have been using the arduino language for a short time, and it is the first time that I have used arduino due,thanks
Because Zener diodes have a knee in the response, that is, while it starts to conduce at the Zener voltage it will not clamp at the Zener voltage, there is a slope.
So basically you are using the wrong thing if you want to clamp at a voltage. Use a Schottky diode to clamp the voltage to just above the 3V3 rail.
Well good look with keeping the RF out of your Arduino.
What is an Arduino door? Never come across this term. Is this post being generated by some sort of translator program?
I use the web translator, well then I replace the zener, Use a Schottky diode to block the voltage just above the 3V3 track, the Schottky diode, it always goes towards ground, and it needs resistance as per the diagram I attached with the zener,
Since this is map on 3.3v and not on 5 volts, the code amp_50 = map (analogRead (IN_50vI), 512,1023,0,625); is correct, naturally then they will transform into volts.
Thank you and if you have any other suggestions I gladly accept.
Soon
Jacob
No.
The Schottky diode has its anode on A4 and it's cathode on the +3V3 power supply. It does not need a resistor like a Zener diode.
If you want more about protection read my simple tutorial on this at:-
Protection
Or see this more comprehensive guide at:-
Protecting inputs
Or download this other booklet on this link:-
Booklet
Thanks for your reply, I'll look at the links you sent me, see you soon. Jacob
This topic was automatically closed 180 days after the last reply. New replies are no longer allowed.