Electrical – Connecting ESP8266 with STM32 Nucleo

Turns out that the Nucleo likes to connect under reset, maybe something to do with the mbed bootloader.

This can pretty easily be resolved by changing the settings of the st-link debugger in uVision to connect under reset.

On a side note, if you create a new project using STM32CubeMX, it also tends to set the port as 'JTAG' rather than 'SW'.

I solved it by increasing the delay for establishing the Wifi connection after the reset. For those who might find this helpful, the working code is as below:

#include "mbed.h"  

Serial esp(D8, D2);  
DigitalOut myled(LED1);

void flush(void) {  
    while (esp.readable()) {  
        (void)esp.getc();  
    }    
}

char server[]="GET /update?api_key=9FL*********C2&field2=";

int main() {  
    int x=7;
    esp.baud(115200);
    flush();  

    esp.printf("AT+RST\r\n"); /* reset module */  
    wait(2);  
    flush();  

    esp.printf("AT+CWMODE=3\r\n");  
    wait(1);  
    flush();  

    // The huge delay was key to obtaining the IP address, so that further commands don't interfere with the ongoing process
    esp.printf("AT+CWJAP=\"Harsha\",\"*******\"\r\n"); /* configure as access point */  
    wait(20);  
    flush();  

    esp.printf("AT+CIPMUX=1\r\n");
    wait(5);
    flush();  
    //response();
    esp.printf("AT+CIPSTART=0,\"TCP\",\"api.thingspeak.com\",80\r\n");  
    wait(5);
    flush();  
    //response();

    esp.printf("AT+CIPSEND=0,%d\r\n", sizeof(server)+15);  
    wait(3);
    flush();  
    //response();

    esp.printf("%s", server);
    esp.printf("%d", x);
    esp.printf(" HTTP/1.0\r\n\r\n\r\n\r\n\r\n");
    wait(2);
    flush(); 

    while(1) {  
        //To indicate completion
        myled = 1;
        wait(0.1);
        myled = 0;
        wait(0.1);
    }   
    return 0;  
}