Hi, folks. I am curious about a detail of AD converters in Arduino processors. On a UNO or NANO, the ATmega328p has a 10-bit AD converter, so it can return unsigned integer values from 0 (representing an input of 0V) to 1023 (representing an input of …, what exactly?) I don't really know how the …

[image] DuinoSoar: 1023 (representing an input of …, what exactly?) The default voltage which the arduino uno compares with comes from the voltage regulator (5V) and it should be pretty much 5V. So 0 is 0 V and 1023 is 5V. When you do the proportion the second one is corrected float Vx = 5…

Assuming that the ADC reference voltage is 5.000V, an ADC value of 1023 represents a voltage that is slightly above about 4.995V, including possibly higher than 5.000V. More than that you cannot say. Likewise, a value of 0 represents a voltage that is between and including 0 to slightly below 0.00…

[image] DuinoSoar: BTW (and unrelated to the above, but sort of related to AD converters :wink:) I once read that reading in an AD converter value from an unconnected (i.e. open) AD pin, makes a good source of randomness for seeding the Arduino random number generator. Is that good advice? No…

When asked this question, I usually simply ask back "Why do you think 4.096V voltage reference devices exist?" (Really though, it makes no practical difference)

[image] anon4567132: So 0 is 0 V and 1023 is 5V. No, 1023 represents the reference voltage, minus 1 LSB* (at least that's what the AVR 328 reference usually states - other devices are different) * and above (That dot is supposed to be an asterisk. Grrrrr)

[image] anon73444976: No, 1023 represents the reference voltage, minus 1 LSB* (at least that's what the AVR 328 reference usually states - other devices are different) Thanks, "AWOL". That is exactly the answer I was looking for. So, in the '328, using 5.0V as reference, then 1023 represent…

This has been discussed quite often. But think of it like this: Your measuring range is 0 to 5 volts and, unlike a Uno etc. which has a 10 bit ADC you have only a 1 bit ADC. This would give you the ability to measure voltage to a rather rough precision to the one of two 2.5 volts blocks. That is …

I know it is not "cryptographic" quality to use the unconnected AD as a random seed source but, then again, using the Arduino PRNG is an absolutely terrible idea for cryptographic work. But when a "random" source is needed for something that does not require "true randomness" (e.g. games, or someth…

@6v6gt Thanks for that amplification!* :grinning: It really did help me to understand better. *Your user ID reminds me that, when I sat my exam for my first amateur radio licence, way back in the early 1970's, I had to draw the schematic and explain (to the examiner), circuit diagrams for a transm…

Ah, well you see, my screen name came from my first big electronics project: [6V6GT] The author was also famous (or infamous) for publishing publishing a lot of designs which, by today's standards, would have been considered lethal. Recklessly using rectified mains voltage to achieve high tension…

Correct divisor for AD conversions?

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Coding_Badly May 11, 2021, 7:06pm 16

No.

Ditto.

Pick a generator that suites your needs. Use something like this to reseed.

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Correct divisor for AD conversions?

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