STM32F411 BlackpillV2 ST core - problem with reading data from RS485 (HW serial 2)

  • Hi,
    for years Im using MySensors 2.3.1 lib running on Bluepill (STM32F103C8T6 Roger`s STM32 core) with RS485 transport as a node without any problems. Now I need to add new node so I decided to use BlackPill 2 (STM32F411) with STM32 ST core and Whisky Delta fork . ( I have no problem with code compilation of simple test node sketch but node is not receiving data from gateway through RS485.

    As you can see from debug log, node send a message and GW replied but node does not received anything. Strange thing is that some chars appeared in debug console "�vXvv���" before 2215 ?TSF:MSG:SEND,.....

    For testing purpose Iv got on desk Ardu Nano as GW with MAX485 converters and as a node I tested with Whisky Delta lib one by one Arduino Mega2560 , Bluepill STM32F103c8t6 , Blackpill2 STM32F411 and F4VE (STM32F407VET). As a node is working only Mega2560. Bluepill were frozen after first attempt to pair with GW. Blackpill 2 and F4VE are repeating sending request for pair to GW with this strange chars in serial debug. ("�vXvv���")

    Im sure that HW is ok. (wiring,DE+RE,termination resistors,5V supply of MAX485, etc)

    Does anybody else has a problem like this ? Do you have any idea where should be a problem ?

    Gateway received data from node and responded

    0;255;3;0;9;8233171 TSF:MSG:READ,118-118-255,s=255,c=3,t=7,pt=0,l=0,sg=0:
    0;255;3;0;9;8233177 TSF:MSG:BC
    0;255;3;0;9;8233180 TSF:MSG:FPAR REQ,ID=118
    0;255;3;0;9;8233184 TSF:PNG:SEND,TO=0
    0;255;3;0;9;8233187 TSF:CKU:OK
    0;255;3;0;9;8233190 TSF:MSG:GWL OK
    0;255;3;0;9;8233447 TSF:MSG:SEND,0-0-118-118,s=255,c=3,t=8,pt=1,l=1,sg=0,ft=0,st=OK:0

    Node trying to pair but does not receive data from gateway. What are chars �vXvv��� ?

    2050 MCO:BGN:INIT OK,TSP=0
    2213 TSM:FPAR
    �vXvv���2215 ?TSF:MSG:SEND,118-118-255-255,s=255,c=3,t=7,pt=0,l=0,sg=0,ft=0

    Simple node sketch. Debug is using Serial1 and MAX485 is using Serial2

    #define MY_DEBUG                          
    #define MY_TRANSPORT_WAIT_READY_MS 2000  
    //#define MY_RS485_SOH_COUNT 2
    #define MY_NODE_ID 118
    #define MY_RS485
    #define MY_RS485_DE_PIN PB3
    #define MY_RS485_HWSERIAL Serial2
    #define MY_RS485_BAUD_RATE 9600
    #include <MySensors.h>
    #define CHILD_ID_SudyNode 0
    MyMessage msgStatus(CHILD_ID_SudyNode, V_VAR1); //Status
    MyMessage msgErrorEvent(CHILD_ID_SudyNode, V_VAR2); //Err event
    MyMessage msgDebug(CHILD_ID_SudyNode, V_VAR3); //DEBUG
    void presentation() {  sendSketchInfo("TestNODE", "Ver. 1");present(CHILD_ID_SudyNode, S_CUSTOM);}
    void setup() {
    String SendBuffer = "TEST Message";
    unsigned long CasovacMillis = millis();
    void loop() {
    if ((millis() - CasovacMillis) >= 3000) { 
     Serial.println("NODE ALIVE");
     CasovacMillis = millis();
    void receive(const MyMessage &message) {
      if (message.sensor == 123 ) {
          String BufferString = message.getString();
          char CommandBuffer[BufferString.length()];
          BufferString.toCharArray(CommandBuffer, BufferString.length()+1); 
          Serial.print("RECEIVED DATA: "); Serial.println(CommandBuffer);

  • OK problem found. Found out that when I selected "Blackpill F411CE" board before code compilation everything were ok.
    Usually I am choosing generic types so I used "F411CEUx" in case of blackpill 2 and I found out that generic types has different default "Serial" pins in ST core. Now I can confirm that Bluepill , Blackpill and F4VE board are working with MAX485.

    ST core v 2.4.0.


    // UART Definitions
      #define SERIAL_UART_INSTANCE  2
    // Default pin used for generic 'Serial' instance
    // Mandatory for Firmata
    #ifndef PIN_SERIAL_RX
      #define PIN_SERIAL_RX         PA3
    #ifndef PIN_SERIAL_TX
      #define PIN_SERIAL_TX         PA2


    // UART Definitions
      #define SERIAL_UART_INSTANCE  1
    // Default pin used for generic 'Serial' instance
    // Mandatory for Firmata
    #ifndef PIN_SERIAL_RX
      #define PIN_SERIAL_RX         PA10
    #ifndef PIN_SERIAL_TX
      #define PIN_SERIAL_TX         PA9

    So be carefull while using ST core and generic type of STM32.

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