2 years, 2 months ago.

Ask how to connect external power.

Hi! there~

The board I use is NUCLEO-F401RE.

I want to use it as if I connected usb by external power without using usb connection with power. I closed the JP5's No. 1 and 2 and tried to connect the 9V to the VIN, but the board did not turn on. As a result, I burned the board twice. So I'm trying to connect the auxiliary battery. It is an auxiliary battery with a output of 2A at 5V. When I connected it, the red light on LD1 kept blinking, the yellow light on LD2 and the red light on LD3. I don't think that the red light on LD1 keeps blinking was a normal connection. If you know how to solve this problem, I want you to let me know. I'll thank you in advance!

1 Answer

2 years, 2 months ago.

You should be able to connect 9V to the VIN pin (CN6 pin 8 or CN7 pin 24) and connect JP5 pins 2 and 3, leave pin 1 unconnected.

U3 will then regulate the 9V down to 5V which will pass through JP5 to the system +5V rail.

It did, but as soon as it was connected, the board broke. Can you tell me what U3 means? Thank you so much for your answer.

posted by m yeee 30 Jul 2019

U3 is one of the parts on the board. It's a LD1117S50TR voltage regulator what should take anything from around 6.1 V to 15 V and regulate it down to 5 V, the exact voltage limits depend on current draw and temperature but 9 V should be fine.

If you look at https://www.st.com/en/evaluation-tools/nucleo-f401re.html and then click on resources one of the options are the schematics for the board. If you download that and open the .pdf file the power supply circuit is on the first page. As long as you have VIN and ground connected and JP5 on pins 2 and 3 is should all work.

What do you mean by the board broke? Did one of the parts fail permanently or do you mean it didn't run but worked again when you removed the battery?

Did you have anything other than the battery connected at the time?

posted by Andy A 30 Jul 2019

Yes, the board burned and it didn't turn on at all. Back then, I used a 9V battery. No other sensors, no PCs, no USBs. It was just a board and a battery. Because of the 9V connection, I've broken the board twice and won't use this method. First of all, I want to connect to the secondary battery, but when I connect the LCD and the auxiliary battery to the board I use, the LCD worked, but the red light on LD1 keeps blinking. Do you know what this is? I didn't blink when I connected to the original PC. Thanks again for your answer. You'll be blessed.

posted by m yeee 31 Jul 2019