I noticed that the voltage at the +5V output of my nano every is only 4.67V, even with no further hardware connected to that pin (or any other pin).
I check it with the nano every powerd via USB and via an external (12V) power supply.
The multimeter is OK (78L05 output measures 4.98V).
Is this normal or is my nano every (original Arduino, not a clone) not working properly?
Rik
The voltage does seem very low but I wonder if the Arduino is putting spikes on the 5v line and it would be interesting to have a look with an oscilloscope what is going on? or maybe put a smoothing capacitor across it and see if this makes a difference?
I know I have experienced this type of thing with esp8266 or esp32 when using Wifi.
BTW - I did post a link but later realised I was looking at the wrong board - Doh!
Things are getting more weird:
With +12V connected to VIN and USB cable connected to PC the board draws no current from the external power supply.
When disconnecting the USB port (to PC) the board draws 12mA from the external power supply and the +5V rises to 4.97V.
After reconnecting the USB cable to the PC the +5V stays 4.97V and the board keeps drawing 12mA from the external 12V supply.
It seems the nano every board is just checking presence of a external supply voltage at power up ?
Just had a look with a scope: 20mVpp noise, no strange spikes.
It seems that the nano every board ignores any voltage applied to VIN if not present at power up.
That can be a pain in my application.
When just the USB is connected for power, diode D2 is used to provide 5V from the USB connector (with a small voltage drop that you are seeing. I would suspect the voltage regulator MPM3610 is simply not starting up (is disabled) when the output voltage is already present. Looking at the data sheet for that part, I could find nothing about operation in that mode, and in most applications there would not be voltage present!
If you want to force the board to be only powered from VIN you could perform board surgery and remove D2.
It seems indeed the MPM3610 not starting up when VUSB is present before VIN.
I solved the problem by adding a 78L05 to power the peripheral electronics.
But I believe this could be solved on the board by adding a diode at the MPM3610 output pin:
That might work, but if the MPM3610 is being held off by the voltage on the feedback FB pin then that wouldn't work. You would need to place the resistor divider before the diode (again reducing 5v voltage). But, frankly, powering the peripherals separately is the best way to go!
Indeed an external +5V (78L05) works fine.
The external +5V is connected to a digital input pin, so the Nano "knows" if the external PS is available or not.
My Nano Every Has 5.08 V coming into the USB port p1 to p5. But ground pin to Vin pin is showing 5.64V with the board just sitting on its header pins, no connections? Very confusing.
(With Battery Vin (only)@12.9 V, 5V NE pin is 4.96V and USB (only) 5V pin is 4.78V. Both sources 4.96V@ 5V pin) To read these voltages and power via Batt, I had to reconnect the NE board to my custom board. In addition to the MCP23017 module, I am powering a DS3231 RTC module. With the modules removed, 5V pin on the NE goes to 4.8V, no change with the Batt sourcing, still 4.96V. Kinda rules out an overload of the 5V pin.
The reason I am looking here is because I have a system in the works with a problem when I power the board with a 12V SLA battery. A MCP23017 module (powered from the NE 5V pin) test sketch works great when running on USB only, yet when the battery is connected, I can no longer reset the MCP interrupts if a button is held too long and repeats. The interrupt pin just stays locked in a low state.
So, I am stuck, and ended up here. I have tried powering in different order (e.g.; USB then Batt, or Batt then add USB. Both methods fail the same way. If a button is never held too long, the interrupts work fine under battery, but that is not very error proof.
The processor continues to run, just the interrupts are locked out.
Any Thoughts? I have rewritten the 23017 code, and as I said, it verifies fine until I add the battery. Voltages on the 23017 power pin is same as above. Suggestions?
Edit:
Today I added a .1uF cap to the MCP module pins, re-verified no inputs are "sticking" low causing a continuous interrupt, yet, the interrupt pin remains low after multiple button pushes with 12V battery power, and no issues when powered by USB. Next I'll add a .1uf to the castellated contacts between 5V and ground on the Every. And, finally, I'll mock up a 5V external linear reg off the 12V if the cap doesn't work. (Sad, as that will mean a new cut in my 1st custom PCB!)
TIA, -fab
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