is it save to supply the MKR 1010 with a higher voltage on the LiPo battery connector? Or more specifically: what is the input range of that input? I'm having kind of a hard time obtaining this info from the documentation...
Background is, I'm having difficulties with power supply via VIN, but the LiPo input works fine. I have 5V available but was wondering if I should add a step-down converter to protect the board...
MKR WiFi 1010 - datasheet (arduino.cc)
Page 2
VINMax Maximum input voltage from VIN pad -0.3 - 5.5 V
Plain as day.
What Idahowalker is saying is : No, use the 5V pin.
You should fix the problem with 5V pin.
Why does it not work ? Is something wrong with your 5V power supply ?
The BQ24195L chip is used to charge the battery and boost the voltage. The battery voltage is maximum 4.4V. Disturbing a charging circuit with a power supply is not okay anyway.
The board automatically switches between USB power and VIN power.
The 5V from the USB connector (VBUS) is directly connected to the +5V.
With 5V at VIN, there is a voltage drop over the diode, with nothing at VIN, the mosfet turns on.
Perhaps there is something in between, if the 5V at VIN is too low, or the USB 5V is too low with a cheap USB cable.
@Koepel thanks a lot! Understanding & fixing the issue with VIN is what I hope to achieve on the long run...
To clarify,
Is that even possible ? Wifi + Ethernet ?
Arduino MKR WiFi 1010 : https://store.arduino.cc/products/arduino-mkr-wifi-1010
Arduino MKR ETH Shield : https://store.arduino.cc/products/arduino-mkr-eth-shield
The MKR ETH Shield runs on the 5V pin (Not the VIN pin, not the 3.3V pin) and makes its own 3.3V.
The NINA Wifi block might use a peak current of 250mA and the W5500 on the shield might use 150 mA (I'm not sure what it uses).
That makes 400mA, which is a lot for a small module.
It is slowly dawning on me what is going on.
The VIN power does not flow back into the computer via the USB connector, so there is no path from VIN to the 5V pin (which is directly connected to the USB 5V).
The shield uses the 5V for power, but there is not any.
You found a design mistake.
Since both the board and shield run on 3.3V, which they make from 5V, I suggest to power the shield with two diodes. One diode from the VIN and one diode from the 5V. Would it be possible for you to change that on the shield ?
Other MKR boards and other MKR shields use other circuits. I think that a MKR Zero would work with this shield, and the board works with other shields. It is just this combination that fails.
@Koepel I think I should have asked about the actual VIN problem directly ... and yes, that's the products I'm using. So I measured some voltages...
supply 5V via VIN
supply 5V via USB
Now if I have the MKR 1010 and the ETH shield put separately and connected via cables, I can supply the board with 5V via VIN and use the same 5 volts to power the ETH shield via +5V - all working fine in this case!
What is still unclear to me: the datasheet of the ETH shield says it uses an AP2112 to make its 3.3V, https://www.diodes.com/assets/Datasheets/AP2112.pdf - so shouldn't 4.3V input be enough? Is it because there's also insufficient current available from the board's +5V pin?
The 3.3V version has only a voltage drop of 125mV at 300mA, so 4.3V should be enough.
Perhaps the +5V voltage drops more when the W5500 starts to work.
If you connect the power supply to the +5V of the shield and put that shield into the board and connect the board to a computer and turn the computer off, then you might see some smoke trying to escape.
well, it's time for a clean-up before Christmas anyway... For now, I'll have to leave this project for some time; might tackle the VIN problem specifically in a new post here if I don't find a satisfactory solution.
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