STM32F401RE  Nucleo sensor hats - Page 1
Forum section: electronics / general

author: maxvonsudo
author_rank: Newbie
timestamp: October 01, 2025, 12:55:40 pm
content: Hello,I assume that Nucleo-compatible hardware, like the STM32F401RE and X-NUCLEO-53L7A1, are supposed to work together and draw power from the ST-Link USB, without requiring some other source of power. Is that correct?I've got a STM32F401RE and X-NUCLEO-53L7A1 and I can't get:(a) a stable ST-Link debugging connection via USB(b) a stable serial link to see what is happening inside my program once flashedThe F401RE works fine and the program is flashable as long as the sensor hat is not on the board. USB / ST-Link connection is totally reliable.Once the X-NUCLEO-53L7A1 is snapped into place using Arduino pins, USB connectivity becomes very inconsistent.Any ideas?

author: Pseudobyte
author_rank: Frequent Contributor
timestamp: October 01, 2025, 01:36:36 pm
content: I would make sure your pin assignments are not conflicting with the expansion board's pins. That is if you are even using other pins.Are you using the virtual serial port built into the stlink?It could also be a power thing with your USB port. Do you have a consistent 5V supply? Is the 3V3 supply stable, i think there is an LDO on the nucleo and one on the eval board?

author: maxvonsudo
author_rank: Newbie
timestamp: October 01, 2025, 03:09:04 pm
content: I used STM32Programmer to do a full erase before re-flashing without the sensor hat on, using the example code athttps://github.com/STMicroelectronics/x-cube-tof1/tree/main/Projects/NUCLEO-F401RE/Examples/53L7A1/53L7A1_SimpleRanging- so I assume that the pins shouldn't be conflicting after re-connecting the sensor hat. Is that a reasonable assumption?Power-wise, I am going mini-USB cable through a powered USB hub, so I assume that I have a reasonable amount of power going through it.I have tried on both a M1 mac and a Linux machine, both of them show the same symptoms. On the Linux machine specifically, when the sensor is disconnected, the board makes a "mount" sound when it gets plugged in. But when the sensor hat is on, no mount sound occurs.

author: thm_w
author_rank: Super Contributor
timestamp: October 02, 2025, 12:28:50 am
content: https://www.st.com/en/evaluation-tools/x-nucleo-53l7a1.html#documentationLooks like there is not much to it, it says 150mA draw max so an average USB port should handle that.You have just that expansion board on without the satellite boards yet right?Jumpers J1 and J2 fitted.Try measuring some voltages, on the USB input at the board, on the adapter board 5V (U1 pin 1) and then on the output of that.

author: maxvonsudo
author_rank: Newbie
timestamp: October 03, 2025, 05:16:12 pm
content: Yes, just the expansion board without any satellite boards.I've got 4.36V between the USB power input and the adapter board 5v pin output, for whatever that's worth.USB input power to U1 pin 1 gives, looks like 0.12V, is that crazy? I am a software guy attempting his second hardware project here.

author: thm_w
author_rank: Super Contributor
timestamp: October 03, 2025, 08:29:58 pm
content: 4.36V is already a bit low, possibly indicating high load.If U1 is 0.12V then something is shorted out or not connected properly, but I'd kind of expect that to take down the entire 5V rail as its directly connected to 5V (CN6 pin 5 goes to U1 pin 1).A cheap $5 inline USB current meter is good for stuff like this.