Tiny machine learning kit shield problem
Hi everyone, we have a small issue we need help with.
We're using the Arduino Tiny Machine Learning Kit and trying to power the Arduino (which is on the shield) through the Vin pin of the shield. We're supplying 3.3V to the Vin pin, coming from a step-down converter that regulates 12V down to 3.3V.
Unfortunately, the Arduino doesn't seem to power up — there's no LED activity or any sign of life. We've connected GND from the power supply to the GND pin of the shield. (Arduino nano 33 BLE Sense lite)
Are we missing something? Is it possible that Vin needs a higher voltage, or is there another issue we’re not seeing?
Thanks in advance for any help
4 Replies
Reading the schematics of the "Arduino Nano 33 BLE Sense" board, the VIN pin goes to a MPM3610 step down converter, which then creates the 3.3V.
https://docs.arduino.cc/resources/schematics/ABX00031-schematics.pdf
Can you measure the voltage at the closed "SJ4" jumper at the bottom of the board with respect to GND? About 3.3V should be there there if if 3.3V is present on VIN. The step-down converter should not need much voltage overhead, even though the datasheet of the Arduino board says at minimum 5V input.
Actually, never mind. The MPM3610A datasheet says it has a VIN under-voltage protection that triggers if VIN is below typically 3.9 Volts, at maximum 4.1V.
https://www.monolithicpower.com/en/documentview/productdocument/index/version/2/document_type/Datasheet/lang/en/sku/MPM3610AGQV-Z
I would suggest raising the VIN voltage either to 5V or connecting the created 3.3V directly to the "3.3V" pin of the board or shield, thus making it power that net directly.
If you use 3.3V directly, there should no other power source present. Otherwise two power supplies will be fighting. If you don't want the MPM3610 creating the 3.3V from VUSB or VIN, then you should either cut the solder jumper SJ4 or use a diode as seen between VBUS and VIN (PMEG6020). Or, make absolutely sure when the USB is plugged in, that your own 3.3V step down converter is turned off.