STM32 Nucleo F411RE: power up issue with USB battery

[Robert Kwan]

Posted on February 28, 2017 at 08:19

Hello!

I am encountering problem that the USB battery cannot power up the STM32 Nucleo F411RE 

after I enabled the UART communication with ESP8266 Nodemcu.

I can have the PC USB working ok and see the UART communication from the COM port on PC.

However, after I replace the PC USB with the USB battery on either the STM32 Nucleo F411RE or the ESP8266 Nodemcu, I would not see any UART communication at all via the COM port.

My USB battery is already with output 5V 1000mA and it is able to drive either the Nucleo board or the ESP8266 Nodemcu before I used the UART communication between them and so I can tell that it's somehow related the UART communication enabled.  But I can't understand why UART would make such a difference?!  My UART setup is primitive and so no sleep mode is used yet.

I even tried directly with USB Wall Charger but I still could not see any UART communication from the COM port then.

Therefore, I doubt if it would help even if I buy new 2000mA USB battery?!

I checked from the other post that this may help:-

https://www.adafruit.com/products/2465

 

But since I have no experience on this, I would like to see if anyone would have similar experience first please.

Thanks & Best Regards,

Robert

[Kraal]

Posted on February 28, 2017 at 10:58

Hi,

If you take a look at the Nucleo64 user manual from ST website, at the bottom of the page 20, it is explained why your setup does not work. It is because the ST-Link part of the Nucleo is waiting for enumeration before powering up the F411RE. Here with the USB battery or USB wall charger, the enumeration never occurs, so the target never starts.

The fix is simple, just put a jumper on JP1 (near the usb port) to power the target anyway.

[Robert Kwan]

Posted on February 28, 2017 at 19:03

Thanks for your comment, Kraal!

As I said before, the F411RE would still be powered up by the USB battery before the UART got enabled

and at that time, I already had the jumper on JP1.

And so, unfortunately, this would not be the solution for this case now!

[Tesla DeLorean]

Posted on February 28, 2017 at 21:56

Update the ST-LINK firmware to current using the utilities. This remedies similar issues on the DISCO boards.

[Robert Kwan]

Posted on February 28, 2017 at 23:04

Thanks Clive but I already did that before I posted my question!

So this does not help my issue unfortunately...

[Kraal]

Posted on March 01, 2017 at 10:39

Yep, my bad, I didn't read carefully enough your message. Can you post the schematic of the connections between the Nucleo and the NodeMCU ? Do they share a common ground ?

[S.Ma]

Posted on March 01, 2017 at 18:59

Is it possible not to use USB plug on Nucleo, connect the USB power bank to the ESP only, then connect RS232 signal, GND and Supply to Nucleo? (so ST Link is out of the equation)? The power bank needs enough draining current from WiFi not to auto switch off (nucleo consumption maybe too small and some power banks self turn off)

And add a SW delay or manually reset Nucleo to make sure the UART communicates when ESP is running.

[Robert Kwan]

Posted on March 01, 2017 at 18:44

No Problem.  Thanks.  Here it is.  I don't have any common ground and you can see that I can plug in the USB battery separately through the mini-USB to the Nucleo board or micro-USB to the ESP8266 Nodemcu.  I need one TX output from D8 of Nucleo to send the data to the RX02 (D7) of the ESP8266 Nodemcu.  And I can add another wire to connect the GND to become common GND?!

[Kraal]

Posted on March 02, 2017 at 07:59

Ok so now it makes more sense. You cannot omit to link the 2 grounds together, as it acts as a reference for the Tx signal for both boards. When you used the PC as power source for both boards, their grounds was more or less the same (depending on the current consumption and the USB cable resistance which is negligible here). Therefore the Tx signal was correctly referenced for both.

Now, I'm quite confident that if you add a wire to link the 2 grounds together so that they are the same it will work.

[Robert Kwan]

Posted on March 02, 2017 at 22:20

Thanks a lot, Kraal!

It works after I connect the GND together and I can even use one USB battery to drive both now

as I use pin 12 of CN7 to give the 3.3V to the Wifi module.

I wonder if I can also raise my baud rate back to 115200 now?!  

I will try that later...

Anyway, thanks again.

Best Regards,

Robert