G120HDR 5v tolerance

NETMF & Gadgeteer
1

Hi,

since i found many different infos about 5v tolerance of boards, i would know it about the G120HDR.

Are digital pins 5v tolerant? Are analog pins 5v tolerant and able to measure from 0 to 5v, or are they able to measure only to 3v3?

Thanks!

2

Pins are 5V tolerant but that does not mean they can measure 5V levels, only 3.3V.

3

Thanks!
So I “don’t know” what they measure if voltage is greater than 3,3, or simply they will measure 3,3 level?
Can I use a voltage divider to change 5v levels to 3,3?

Thanks

4

You should not use more than 3.3v and you can use a voltage divider in most cases

5

Ok, many thanks!

6

as a digital input, when you see a 5v input that’s higher than the “lower limit” value to see this as a “high” on the pin. The digital input pins are tolerant to this, and they’ll just read a 1.

As an analog input, the story is different. Most processors are NOT tolerant to voltages above VCC (ie above 3v3). So don’t connect that as you’ll likely damage the analog input measurement device (the ADC, Analog-to-Digital-Converter) or the multiplexer that is in front of the ADC. Even if it was tolerant, you will only get “full value” at 3v3, so you couldn’t differentiate between a signal that was 3.3 volts from one that was 4.3v or 4.9v… but as Gus mentioned, the G120 ADCs are not 5v tolerant so use a voltage divider to skew your readings to fit within the 0v to 3v3 range.

7

Thanks again!
Well, building the voltage divider, I searched, made my calculations and found that resistors of 3,4 KOhm and 6,6 KOhm should do the job.
I have two last questions about it:
Is the current on the pin using those values correct, or should I reduce or increase resistors?
The new range is strictly 0-3,3 from 0-5. Since I get the 5v voltage from the 5v regulated pin on the g120, can I rely on the new range, or should I reduce it to i.e. 0-3v to be shure not to pass 3,3?

Thank you