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vivitern

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The mod suggested in the link will not change VCC of the CPU, just the voltage of the analog supply pin and maybe some other points on the board. So the CPU will be outside of the allowed voltages. If you really want to change VCC to 5V, you would have to do a similar mod on J22. But I would not do this before checking if all other parts on the board can take the 5V instead of 3.3V AND there will be no parts left hanging on 3.3V, getting a 5V signal from the CPU.
I would not risk to fry my DK for just simply getting a 5V range, a small board with a few OPAs, or one OPA plus some resistors more should do the job.
 
:rolleyes: ... You cannot normally just run any 3.3vdc MCU or CPU on 5vdc and expect proper scalar functionality even if it and other parts can accept
the higher voltage. If it doesn't just fry parts, internal clocks (including the WDT) as well as any other pulse parameters, peripheral controls,
and coms will still run awry.

To adapt running a 3.3vdc MCU in a 5vdc (and higher or lower and even fluctuating) environment typically a filtered buck/boost converter or
a simple low dropout Vreg is employed with ample high frequency blocking and large stability capacitance, such as in a tuned Pi filter. ;)

All this talk of CPU/MCU overvoltage driving is just nonsense because the mentioned "5 volt range" (whether it be the native drive or some external
monitor) is simply a function of either proper drive conditioning or ADC prescaling and has nothing at all to do with whether you can get away with
overating chip voltages. Sensory inputs, such as ADCs can be easily scaled for 5, 50, 500 vdc with any 3.3vdc core. :cool:

It is also evident, by the slinging of terms like "DK" and "OPA", that you guys are: A.) Arduino heads .... B.) On the wrong frikkin forum ... :p
 
vivitern said:
The mod suggested in the link will not change VCC of the CPU, just the voltage of the analog supply pin and maybe some other points on the board. So the CPU will be outside of the allowed voltages. If you really want online Zumba classes to change VCC to 5V, you would have to do a similar mod on J22. But I would not do this before checking if all other parts on the board can take the 5V instead of 3.3V AND there will be no parts left hanging on 3.3V, getting a 5V signal from the CPU.
I would not risk to fry my DK for just simply getting a 5V range, a small board with a few OPAs, or one OPA plus some resistors more should do the job.
Click to expand...
It sounds like the forum member is giving you a very necessary reality check. While it’s tempting to simplify your hardware by modding the board to run at 5V, their warning about the VCC (Core Voltage) vs. Peripheral Voltage is a critical distinction that often leads to "magic smoke" if ignored.

The core of the issue is that most modern Development Kits (DKs) are designed with a specific power architecture where the CPU logic and the I/O pins are tightly regulated. If you only mod the analog supply pin as originally suggested, you create a voltage mismatch. The CPU would essentially be "fighting" itself trying to process logic at 3.3V while the analog interface is forced to 5V. As the poster mentioned, even if you managed to force the CPU to 5V via J22, you'd likely kill other components on the board (like sensors, flash memory, or level shifters) that are hard-wired for 3.3V. Furthermore, the "hanging" signal issue is a real danger. If the CPU sends a 5V signal to a component still powered by 3.3V, you risk triggering the ESD protection diodes on that component, which can lead to overheating or a total short circuit.

The suggestion to use an Operational Amplifier (OPA) or a simple level-shifter circuit is much more professional and safe. By using an external OPA, you can scale your 0–3.3V signal up to 0–5V without stressing the DK’s internal regulators. It keeps your expensive board within its factory specifications while giving you the voltage range you need for your external hardware. It’s a bit more wiring, but it’s significantly cheaper than replacing a fried Development Kit.
 
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