ICMP Ping Failure to Google After PPP Connection on STM32F407

Noushadalik · ‎2024-11-07

Hi,
https://community.st.com/t5/stm32-mcus-products/configuring-ppp-on-stm32f407disc-with-lte-modem-via-usart-using/m-p/728673#M262741

This continues the previous thread discussing the PPPoS implementation for the STM32F407. I successfully established a PPP connection and obtained an IP address. However, my ICMP ping to Google did not receive a successful response. Please check the code snippet below for any necessary changes.

void PPPosClientThread()
{
    osSemaphoreWait(pppos_mutex, PPPOSMUTEX_TIMEOUT);
	pppos_task_started = 1;
	osSemaphoreRelease(pppos_mutex);

    int gsmCmdIter = 0;
    int nfail = 0;
    printf("GSM: Starting Modem thread\r\n");

    char* data = (char*) malloc(BUF_SIZE);

    char PPP_ApnATReq[sizeof(CONFIG_GSM_APN) + 24];
    sprintf(PPP_ApnATReq, "AT+CGDCONT=1,\"IP\",\"%s\"\r\n", CONFIG_GSM_APN);
    cmd_APN.cmd = PPP_ApnATReq;
    cmd_APN.cmdSize = strlen(PPP_ApnATReq);


    //_disconnect(1); // Disconnect if connected  // FOR testing

	osSemaphoreWait(pppos_mutex, PPPOSMUTEX_TIMEOUT);
    pppos_tx_count = 0;
    pppos_rx_count = 0;
	gsm_status = GSM_STATE_FIRSTINIT;
	osSemaphoreRelease(pppos_mutex);

	// GSM reset pin functionality required

	enableAllInitCmd();

    while (1)
    {
        while (gsmCmdIter < GSM_InitCmdsSize)
        {
            if (GSM_Init[gsmCmdIter]->skip)
            {
                #if GSM_DEBUG
                infoCommand(GSM_Init[gsmCmdIter]->cmd, GSM_Init[gsmCmdIter]->cmdSize, "Skip command:");
                #endif
                gsmCmdIter++;
                continue;
            }
            if (atCmd_waitResponse(GSM_Init[gsmCmdIter]->cmd,
                                   GSM_Init[gsmCmdIter]->cmdResponseOnOk, NULL,
                                   GSM_Init[gsmCmdIter]->cmdSize,
                                   GSM_Init[gsmCmdIter]->timeoutMs, NULL, 0) == 0)
            {
                // * No response or not as expected, start from first initialization command
                #if GSM_DEBUG
                printf("GSM: Wrong response, restarting...\r\n");
                #endif

                nfail++;
                if (nfail > 20)
                    goto exit;

                osDelay(3000);
                gsmCmdIter = 0;
                continue;
            }

            if (GSM_Init[gsmCmdIter]->delayMs > 0)
                osDelay(GSM_Init[gsmCmdIter]->delayMs);
            GSM_Init[gsmCmdIter]->skip = 1;
            if (GSM_Init[gsmCmdIter] == &cmd_Reg)
                GSM_Init[gsmCmdIter]->delayMs = 0;
            // Next command
            gsmCmdIter++;
        }

        #if GSM_DEBUG
		printf("GSM: GSM initialized.\r\n");
		#endif

        osSemaphoreWait(pppos_mutex, PPPOSMUTEX_TIMEOUT);
		if(gsm_status == GSM_STATE_FIRSTINIT)
        {
			osSemaphoreRelease(pppos_mutex);

			// ** After first successful initialization create PPP control block
			ppp = pppos_create(&ppp_netif, ppp_output_callback, ppp_status_cb, NULL);

			if (ppp == NULL)
            {
				#if GSM_DEBUG
				printf("GSM: Error initializing PPPoS\r\n");
				#endif
				break; // end task
			}
		}
		else
            osSemaphoreRelease(pppos_mutex);

		//ppp_set_default(ppp);
        netif_set_default(&ppp_netif);
        //ppp_set_auth(ppp, PPPAUTHTYPE_ANY, "", "");

		osSemaphoreWait(pppos_mutex, PPPOSMUTEX_TIMEOUT);
		gsm_status = GSM_STATE_IDLE;
		osSemaphoreRelease(pppos_mutex);
		ppp_connect(ppp,0);

        while(1)
        {
			// === Check if disconnect requested ===
			osSemaphoreWait(pppos_mutex, PPPOSMUTEX_TIMEOUT);
			if (do_pppos_connect <= 0)
            {
				int end_task = do_pppos_connect;
				do_pppos_connect = 1;
				osSemaphoreRelease(pppos_mutex);
				#if GSM_DEBUG
				printf("\r\n");
				printf("GSM: Disconnect requested.\r\n");
				#endif

				ppp_close(ppp, 0);
				int gstat = 1;
				while (gsm_status != GSM_STATE_DISCONNECTED)
                {
					// Handle data received from GSM
					memset(data, 0, BUF_SIZE);
                    int len = UART_Read(data, BUF_SIZE, 30);
					if (len > 0)
                    {
						pppos_input_tcpip(ppp, (u8_t*)data, len);
						osSemaphoreWait(pppos_mutex, PPPOSMUTEX_TIMEOUT);
					    pppos_tx_count += len;
						osSemaphoreRelease(pppos_mutex);
					}
					osSemaphoreWait(pppos_mutex, PPPOSMUTEX_TIMEOUT);
					gstat = gsm_status;
					osSemaphoreRelease(pppos_mutex);
				}
				osDelay(1000);

				osSemaphoreWait(pppos_mutex, PPPOSMUTEX_TIMEOUT);
				uint8_t rfoff = gsm_rfOff;
				osSemaphoreRelease(pppos_mutex);
				_disconnect(rfoff); // Disconnect GSM if still connected

				#if GSM_DEBUG
				printf("GSM: Disconnected.\r\n");
				#endif

				gsmCmdIter = 0;
				enableAllInitCmd();
				osSemaphoreWait(pppos_mutex, PPPOSMUTEX_TIMEOUT);
				gsm_status = GSM_STATE_IDLE;
				do_pppos_connect = 0;
				osSemaphoreRelease(pppos_mutex);

				if (end_task < 0) goto exit;

				// === Wait for reconnect request ===
				gstat = 0;
				while (gstat == 0)
                {
					osDelay(100);
					osSemaphoreWait(pppos_mutex, PPPOSMUTEX_TIMEOUT);
					gstat = do_pppos_connect;
					osSemaphoreRelease(pppos_mutex);
				}
				#if GSM_DEBUG
				printf("\r\n");
				printf("GSM: Reconnect requested.\r\n");
				#endif
				break;
			}

			// === Check if disconnected ===
			if (gsm_status == GSM_STATE_DISCONNECTED)
            {
				osSemaphoreRelease(pppos_mutex);
				#if GSM_DEBUG
				printf("\r\n");
				printf("GSM: Disconnected, trying again...\r\n");
				#endif
				ppp_close(ppp, 0);
                _disconnect(1);

				enableAllInitCmd();
				gsmCmdIter = 0;
				gsm_status = GSM_STATE_IDLE;
				osDelay(10000);
				break;
			}
			else
                osSemaphoreRelease(pppos_mutex);

			// === Handle data received from GSM ===
			memset(data, 0, BUF_SIZE);
            int len = UART_Read(data, BUF_SIZE, 50);
			if (len > 0)
            {
                //printf("RX: %d\r\n", len);
                //printf("data :%s\r\n",data);
				pppos_input_tcpip(ppp, (u8_t*)data, len);
				osSemaphoreWait(pppos_mutex, PPPOSMUTEX_TIMEOUT);
			    pppos_tx_count += len;
				osSemaphoreRelease(pppos_mutex);
			}

		}  // Handle GSM modem responses & disconnects loop
	}  // main task loop

exit:
	if (data) free(data);  // free data buffer
	if (ppp) ppp_free(ppp);

	osSemaphoreWait(pppos_mutex, PPPOSMUTEX_TIMEOUT);
	pppos_task_started = 0;
	gsm_status = GSM_STATE_FIRSTINIT;
	osSemaphoreRelease(pppos_mutex);
	#if GSM_DEBUG
	printf("GSM: PPPoS TASK TERMINATED\r\n");
	#endif
	//osThreadTerminate(mythread);
}

Ping code snippet:

void start_ping_action() {
	//get gateway IP from global net interface
	ip_addr_t gw_addr = ppp_netif.ip_addr;
	uint8_t gw_ip_part_1 = ip4_addr1(&gw_addr);
	//check if DHCP already succeeded by checking against non 0 ip part
	int ret = 0;
	if(gw_ip_part_1 != 0) {
		ip_addr_t target_ping_ip;
		//select target:
		//gateway
		//target_ping_ip = gw_addr;
		//static IPs
		//IP_ADDR4(&target_ping_ip, 192,168,1,180);
		IP_ADDR4(&target_ping_ip, 216,58,213,195); //google.com
		//IP_ADDR4(&target_ping_ip, 8, 8, 8, 8); // Google's DNS

		printf("Starting to ping IP: %d.%d.%d.%d.\r\n", (int)ip4_addr1(&target_ping_ip),
				(int)ip4_addr2(&target_ping_ip), (int)ip4_addr3(&target_ping_ip),
				(int)ip4_addr4(&target_ping_ip));
		if((ret = ping_ip(target_ping_ip)) != PING_ERR_OK) {
			printf("Error while sending ping: %d\r\n", ret);
		}
	}
	//every 4 seconds, start a new ping attempt
	sys_timeout(4000, start_ping_action, NULL);
}

void check_ping_result() {
	ping_result_t res;
	memset(&res, 0, sizeof(res));
	int retcode = 0;
	if((retcode = ping_ip_result(&res)) == PING_ERR_OK) {
        if (res.result_code == PING_RES_ECHO_REPLY) {
            printf("Good ping from %s %u ms\r\n", ipaddr_ntoa(&res.response_ip),
                    (unsigned) res.response_time_ms);
        } else {
            printf("Bad ping err %d\r\n", res.result_code);
        }
	} else {
		//printf("No ping result available yet: %d\n", retcode);
	}
	sys_timeout(100, check_ping_result, NULL);
}
/* USER CODE END 0 */

/**
  * @brief  The application entry point.
  * @retval int
  */

Output logs:

UART6 init done
GSM: Starting Modem thread
GSM: AT COMMAND: [AT..]
GSM: AT RESPONSE: [..OK..]
GSM: AT COMMAND: [ATD*99#..]
GSM: AT RESPONSE: [..CONNECT 115200..]
GSM: GSM initialized.
GSM: ppp_status_cb: 0
GSM: status_cb: Connected
GSM:    ipaddr    = 10.220.50.XXX
GSM:    gateway   = 10.64.64.XX
GSM:    netmask   = 255.255.255.255
GSM: LTE Init done
Starting StartDefaultTask
IP:10.220.50.142
Starting to ping IP: 216.58.213.XXX.
Ping timed out
              Bad ping err 0
Starting to ping IP: 216.58.213.XXX.
Ping timed out
              Bad ping err 0
Starting to ping IP: 216.58.213.XXX.
Ping timed out
              Bad ping err 0
Starting to ping IP: 216.58.213.XXX.