Important changes to forums and questions
All forums and questions are now archived. To start a new conversation or read the latest updates go to forums.mbed.com.
7 years, 9 months ago.
STM32 F411RE can't be powered up with USB battery after UART enabled with ESP8266 Nodemcu?
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
4 Answers
7 years, 9 months ago.
Which UART adapter you use? and how you connected it with both boards?
7 years, 9 months ago.
You can't use Serial 2. I think that is connected to the USB connector. I use Serial 6 which is on CN10 for anything I want to connect to the STM32F411RE. You can use a FTDI to convert it to USB.
Thanks but I am using only Serial 1, which are PA9 and PA10 on CN5. In fact, I use only the TX (PA9/D8) from F411RE as shown on my photo just attached. So you can still use USB battery to power up if using Serial 6 pls? If so, I can give it a try to see if any such difference then...
posted by 28 Feb 2017
7 years, 9 months ago.
The picture above seems to have only one wire (Nucleo Tx to ESP8266 Rx). You also need at least a common GND pin between the two devices. This may be provided by the powersupply but that is not clear from the picture.
Also note that if the nucleo is powered by a USB charger or batterypack the STLink interface can not complete the enumeration with the USB host on the PC side. The enum is used to negotiate the power requirements that the nucleo has from the USB port. In case this enum process fails the STLink will not turn on the power for the main processor (no flashing LEDs etc). You can disable the enum process by closing jumper JP1. Check the nucleo manual for details. The picture shows that you have this jumper installed.
7 years, 9 months ago.
I have the same setup, but I used the ESP02 instead of the Node MCU. You can not power the nucleo via the usb connected at the st-link headers to your batteries. The ESP8266 draws as much as 100mA current, when powered, without USB enumeration, the Nucleo can only supply less power to the ESP8266. Connecting the USB to pc is possible since the st-link requests more power during USB device enumeration.
My solution was to power the Nucleo board via the VIN pin (CN6) or E5V pin (CN7), you have to change the jumper JP5 (in your picture it is stil connected to U5V - STLink's USB). Move that jumper to the other side - E5V. Then it should be ok.
Eventually I ended up buying the Adafruit's Power Boost sheild - https://www.adafruit.com/product/2078 which I stacked my Nucleo with.