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UART communication between X-NUCLEO-BNRG2A1 (BlueNRG-M2SP) and Nucleo-G070RB: no response from BNRG

MaxPach
Associate II

Hello everyone,

I am currently having trouble making a simple UART communication (+ the HCI command-based protocol) between the X-NUCLEO-BNRG2A1 shield embedding a BlueNRG-M2 (which itself embeds a BlueNRG-2) and my Nucleo-G070RB. I cannot use SPI for this.

First, on X-NUCLEO-BNRG2A1 side (BlueNRG-2) :

  • I downloaded the FW package STSW-BNRG2N-V320 [https://www.st.com/en/embedded-software/stsw-bnrg2n-v320.html]
  • I used the documentation UM2666 "Getting started with the X-CUBE-BLE2 Bluetooth Low Energy software expansion for STM32Cube" as support,
  • I flashed the X-NUCLEO-BNRG2A1, i-e the embedded BlueNRG-2, using the BlueNRG-1_2 Flasher Utility (STSW-BNRGFLASHER), with the STSW-BNRG2N-V320 in order to emulate it with a BlueNRG-2N
  • I removed all Resistors / Jumpers from the SPI and unnecessary lines : (SPI_MOSI R80 & SPI_MISO R79 ), (SPI_CSN R77), (SPI_IRQ / BOOT R85 & R82) , (SPI_CS R70, R76 & R86), (GPIO R81 & R84), (Jumpers J11, J12, J13, J14, J15 (I have a doubt about J15, but I think this is just required while flashing) )
  • I added all required 0 Ohm Resistors + Jumpers : R83 for DIO12 (SEL pin on BlueNRG-2N) & Jumper J10 (3v3 <-> VDD).
  • I also added 0 Ohm Resistors R71 and R73 as I firstly thought these 2 lines (DIO4 & 5) were the UART lines. But if I understood correctly, these are just for application serial com when used and the emulation of BlueNRG-2N uses the DIO8 & DIO11 as UART Pins.

Then, on NUCLEO-G070RB side (STM32G0xx) :

  • I have an already working project running correctly on this board
  • I took the following project example: STM32L - BLE_Beacon_NWK from BlueNRG-1_2 DK 3.2.3 and extracted all I needed , using the documentation "STM32L - BlueNRG-1,2 network coprocessor (UART mode)" from the doxygen doc as support.
  • I made an UART Rx/Tx module working, using the HCI commands defined in the imported libraries. This module is correctly working in:
    • TX because I validated it using a USB to Serial converter on my laptop with a python script using a hci lib : the data is correctly sent.
    • RX because if I make the loop TX <-> RX on the same UART, I receive exactly what was sent. I haven't tested the reception of HCI Events data, but that is not the pb here.

Finally, I mapped / configured / checked the GPIOs / buses like this:

  • BlueNRG-M2SP Pins 1 & 2 untouched
  • BlueNRG-M2SP Pin 3 = DIO4 = ? < --- > STM32G0xx PA9 = unused & floating
  • BlueNRG-M2SP Pin 4 = DIO5 = ? < --- > STM32G0xx PA10 = unused & floating
  • BlueNRG-M2SP Pin 5 = VDD is correclty at 3V3
  • BlueNRG-M2SP Pins 6 & 7 untouched
  • BlueNRG-M2SP Pins 8 correctly grounded
  • BlueNRG-M2SP Pins 9 untouched
  • BlueNRG-M2SP Pin 10 = DIO8 = UART_TXD (BNRG-2N)  EDIT : BlueNRG-M2SP Pin 11 = DIO11 = UART_RXD (BNRG-2N) < --- > STM32G0xx PB2 = USART3_TX.
    • When unconnected and BlueNRG-M2SP in correct state, pin is correclty floating
    • When connected + a USB Serial converted RX wire connected, HCI data is good (interpreted by py python)
  • BlueNRG-M2SP Pin 11 = DIO11 = UART_RXD (BNRG-2N)  EDIT : BlueNRG-M2SP Pin 10 = DIO8 = UART_TXD (BNRG-2N)  < --- > STM32G0xx PB0 = USART3_RX
    • When unconnected and BlueNRG-M2SP in correct state, pin is correclty at 3V3, and drops to floating when BlueNRG-M2SP is in reset
    • When connected to RX wire of a USB Serial converter or a Scope NOTHING, stays at 3v3
  • BlueNRG-M2SP Pins 12 to 18 untouched
  • BlueNRG-M2SP Pin 19 = RESETN < --- > STM32G0xx PA8 = GPO set to 1 when want to enable the BRNG. Correctly set to 1 during communication
  • BlueNRG-M2SP Pin 19 = DIO12 = SEL (BNRG-2N) < --- > STM32G0xx PB4 = GPO set to 1 when want to enable the UART. Correctly set to 1 during communication


As a result, BlueNRG-M2SP should be working as BlueNRG-2N: is powered up & grounded correclty, is enabled (resetn = 1) & SEL pin = 1 for UART, has UART TX & RX mapped & receives good HCI commands, but no response and my application commands end all in timeout.

I tried swapping RX & TX just in case, nothing either.

Have I missed something ? Like the DIO 4 & 5 are maybe the ones to use ? The "emulation" FW is not UART HCI protocol compatible ?

I really appreciate any response, I am a bit in a pickle here ... ‌:face_with_rolling_eyes:‌

Max.Pach

3 REPLIES 3
MaxPach
Associate II

UP :thumbs_up:

MaxPach
Associate II

Nevermind, seems to come from the way you flash the BlueNRG board ...

I was using the X-NUCLEO-BNRG2A1 & the STEVAL-IDB008V2. Using the latter, I of course made the HW workarounds to enable external com without having the embedded components in the way.

 

Using RF Flasher and a bunch of different Example apps (DTM Uart, Beacon, the BlueNRG 2N "emulation"), no response, on both boards.

  • SWD only for X-NUCLEO-BNRG2A1
  • SWD & UART with STEVAL-IDB008V2 (as there is a USB to serial converter STM32 on the board that manages that flashing function). No response with GUI either.

 

Using the BlueNRG DK graphical app, I managed to flash through UART the STEVAL-IDB008V2 with a DTM Uart image that now communicates with Both GUI & my FW on external Nucleo-G070RB. Howerver, when I compare the flash with the DTM Uart image using RF Flasher, there are differences.

I am really confused with that. This should not happen. Flashing the device with an example bin from the BlueNRG DK folders through RF Flasher should work. Now I am stuck with the X-NUCLEO-BNRG2A1 not working as there is no way to program it using the BlueNRG DK graphical app.

So what I am missing there ? I will try on Ubuntu using OpenOCD but I fear the same result will happen.

MaxPach
Associate II

I also fear that posts on this community forum are too often un-replied.

I stopped counting un-replied posts that I found looking for different answers around ST µcontrollers ...