UDP client does not start to send in AP mode

[GvTardy]

Hi to everybody,

I have a problem with a UDP client setup:

I start a DHCP server, then
WIFI in AP mode.
Once this is done I start a UDP client in a task.

This works all without problems, I can connect to it with my computer, receive an address and start sending UDP messages.
The bad thing is: I do not receive any of these messages until I send at message from the UDP server on my computer to the ESP32. This message from my terminal program (YAT) seems to wake up a part of the ESP, as after this, I get the messages.

Here's the code:
Initialisation of the tcpip adapter and ESP32 as softAP:

Code: [Select all] [Expand/Collapse]

1. EventGroupHandle_t wifi_event_group;
2. const int AP_STARTED_BIT = BIT0;
3. const int STA_CONNECTED_BIT = BIT1;
4. const int STA_DISCONNECTED_BIT = BIT2;
5. const int UDP_SOCKED_BINDING = BIT3;
6.  
7. static esp_err_t event_handler(void *ctx, system_event_t *event)
8. {
9.     switch(event->event_id) {
10.     case SYSTEM_EVENT_AP_START:
11.         ESP_LOGI("WIFI_AP","ESP32 is started in AP mode");
12.         xEventGroupSetBits(wifi_event_group, AP_STARTED_BIT);
13.         break;
14.        
15.     case SYSTEM_EVENT_AP_STACONNECTED:
16.         ESP_LOGI("WIFI_AP", "station:"MACSTR" join, AID=%d",
17.                  MAC2STR(event->event_info.sta_connected.mac),
18.                  event->event_info.sta_connected.aid);
19.         xEventGroupSetBits(wifi_event_group, STA_CONNECTED_BIT);
20.         esp_wifi_set_ps(WIFI_PS_NONE);
21.         break;
22.  
23.     case SYSTEM_EVENT_AP_STADISCONNECTED:
24.         ESP_LOGI("WIFI_AP", "station:"MACSTR"leave, AID=%d",
25.                  MAC2STR(event->event_info.sta_disconnected.mac),
26.                  event->event_info.sta_disconnected.aid);
27.         xEventGroupSetBits(wifi_event_group, STA_DISCONNECTED_BIT);
28.         break;     
29.     default:
30.         break;
31.     }
32.     return ESP_OK;
33. }
34.  
35. void DHCP_server_init(){
36.    
37.     // initialize the tcp stack
38.     tcpip_adapter_init();
39.     // stop DHCP server
40.     ESP_ERROR_CHECK(tcpip_adapter_dhcps_stop(TCPIP_ADAPTER_IF_AP));
41.     // assign a static IP to the network interface
42.     tcpip_adapter_ip_info_t info;
43.     memset(&info, 0, sizeof(info));    
44.     info.ip.addr = inet_addr(WIFI_IP_ADDR);
45.     info.gw.addr = inet_addr(WIFI_IP_ADDR);
46.     //IP4_ADDR(&info.ip, 192, 168, 1, 1);
47.     //IP4_ADDR(&info.gw, 192, 168, 1, 1);//ESP acts as router, so gw addr will be its own addr
48.     IP4_ADDR(&info.netmask, 255, 255, 255, 0);
49.     ESP_ERROR_CHECK(tcpip_adapter_set_ip_info(TCPIP_ADAPTER_IF_AP, &info));
50.     // start the DHCP server  
51.     ESP_ERROR_CHECK(tcpip_adapter_dhcps_start(TCPIP_ADAPTER_IF_AP));
52.     printf("DHCP server started \n");
53. }
54.  
55. void WIFI_AP_init(void)
56. {
57.  
58.     ESP_ERROR_CHECK( esp_event_loop_init(event_handler, NULL) );
59.     wifi_event_group = xEventGroupCreate();
60.     DHCP_server_init();
61.    
62.     //xTaskCreate(&tcp_server,"tcp_server",4096,NULL,5,NULL);
63.     esp_log_level_set("wifi", ESP_LOG_NONE); // disable wifi driver logging
64.     wifi_init_config_t cfg = WIFI_INIT_CONFIG_DEFAULT();
65.     ESP_ERROR_CHECK( esp_wifi_init(&cfg) );
66.     ESP_ERROR_CHECK( esp_wifi_set_storage(WIFI_STORAGE_RAM));
67.     ESP_ERROR_CHECK( esp_wifi_set_mode(WIFI_MODE_AP) );
68.  
69.     // configure the wifi connection and start the interface
70.     wifi_config_t ap_config = {
71.         .ap = {
72.             .ssid = AP_SSID,
73.             .password = AP_PASSPHARSE,
74.             .ssid_len = strlen(AP_SSID),
75.             .channel = 0,
76.             .authmode = AP_AUTHMODE,
77.             .ssid_hidden = AP_SSID_HIDDEN,
78.             .max_connection = AP_MAX_CONNECTIONS,
79.             .beacon_interval = AP_BEACON_INTERVAL,         
80.         },
81.     };
82.  
83.     if (strlen(WIFI_PSWD)==0)
84.         ap_config.ap.authmode = WIFI_AUTH_OPEN;
85.  
86.     ESP_ERROR_CHECK(esp_wifi_set_config(WIFI_IF_AP, &ap_config));
87.     ESP_ERROR_CHECK( esp_wifi_start() );
88.     printf("ESP WiFi started in AP mode \n");
89.  
90.     xTaskCreate(&task_UDP_client, "UDP", 4096, NULL, 5, NULL);
91. }
92.  
93.  

GeSHi © Codebox Plus Extension

and here my UDP_client task:

Code: [Select all] [Expand/Collapse]

1. int udp_socket_tx;
2. int udp_socket_rx;
3. struct sockaddr_in udp_sender;
4. struct sockaddr_in udp_receiver;
5.  
6. void task_UDP_client(void *pvParameters)
7. {
8.     uint16_t cnt = 0;
9.     char rx_buffer[128];
10.     char addr_str[128];
11.     int addr_family;
12.     int ip_protocol;
13.  
14.     while (1) {
15.  
16.         ESP_LOGI("WIFI","Waiting for Station");
17.  
18.         EventBits_t staBits = xEventGroupWaitBits(wifi_event_group, STA_CONNECTED_BIT, pdTRUE, pdFALSE, portMAX_DELAY);
19.  
20.         if((staBits & STA_CONNECTED_BIT) != 0)
21.             ESP_LOGI("UDP","Connected, starting UDP_Client\n");
22.         else {
23.             ESP_LOGI("UDP", "timeout waiting for connection...");
24.             break;
25.         };
26.  
27.         udp_socket_tx = socket(PF_INET, SOCK_DGRAM, IPPROTO_IP);
28.  
29.         if (udp_socket_tx < 0) {
30.             ESP_LOGE("UDP", "Unable to create socket: errno %d", errno);
31.             xEventGroupClearBits(wifi_event_group, UDP_SOCKED_BINDING);
32.             break;
33.         }
34.         else{
35.             ESP_LOGI("UDP", "Socket created");
36.             xEventGroupSetBits(wifi_event_group, UDP_SOCKED_BINDING);
37.         };
38.  
39.  
40.         udp_sender.sin_family = AF_INET;
41.         udp_sender.sin_len = sizeof(udp_sender);
42.         udp_sender.sin_addr.s_addr = inet_addr(UDP_SENDER_ADDR);
43.         udp_sender.sin_port = htons(UDP_SENDER_PORT);
44.  
45.         if(bind(udp_socket_tx, (struct sockaddr *)&udp_sender, sizeof(struct sockaddr_in)) == -1) {
46.             ESP_LOGE("UDP", "bind failed");
47.             close (udp_socket_tx);
48.             exit(1);
49.         }
50.         else
51.             ESP_LOGI("UDP", "bind created");
52.  
53.         udp_receiver.sin_family = AF_INET;
54.         udp_receiver.sin_len = sizeof(udp_receiver);
55.         udp_receiver.sin_addr.s_addr = htonl(UDP_RECEIVER_ADDR);
56.         udp_receiver.sin_port = htons(UDP_RECEIVER_PORT);
57.  
58.         while (1) {
59.  
60.             static const char *msg = "test UDP send \n";
61.  
62.             vTaskDelay(2000 / portTICK_PERIOD_MS);
63.  
64.             cnt++;
65.  
66.             char text[128];
67.             sprintf(&text[0],"UDP message %d", cnt++);
68.             int err = sendto(udp_socket_tx, text, strlen(text), 0, (struct sockaddr *)&udp_receiver, sizeof(udp_sender));  
69.             //int err = UDP_send("UDP: msg no %d", cnt);
70.  
71.             //int err = sendto(udp_socket_tx, msg, strlen(msg), 0, (struct sockaddr *)&udp_receiver, sizeof(udp_sender));
72.             if (err < 0) {
73.                 ESP_LOGE("UDP", "Error occured during sending: errno %d", errno);
74.                 break;
75.             }
76.             else
77.                 ESP_LOGI("UDP","send to %s ",  ip4addr_ntoa(&(udp_sender.sin_addr)));
78.  
79.            
80.  
81.             ESP_LOGI("UDP", "Message %d sent", cnt);
82.  
83.             #ifdef UDP_WAIT_FOR_REPLY
84.             /*  //struct sockaddr_in sourceAddr; // Large enough for both IPv4 or IPv6
85.             socklen_t socklen = sizeof(udp_receiver_addr);
86.             int len = recvfrom(udp_socket_rx, rx_buffer, sizeof(rx_buffer) - 1, 0, (struct sockaddr *)&udp_receiver_addr, &socklen);
87.             //int len = recv(udp_socket, rx_buffer, sizeof(rx_buffer) - 1, 0);
88.  
89.             ESP_LOGI("UDP", "past recvfrom");
90.  
91.  
92.             // Error occured during receiving
93.             if (len < 0) {
94.                 ESP_LOGE("UDP", "recvfrom failed: errno %d", errno);
95.                 break;
96.             }
97.             // Data received
98.             else {
99.                 rx_buffer[len] = 0; // Null-terminate whatever we received and treat like a string
100.                 ESP_LOGI("UDP", "Received %d bytes from %s:", len, addr_str);
101.                 ESP_LOGI("UDP", "%s", rx_buffer);
102.             }*/
103.             #endif
104.            
105.         }
106.  
107.         if (udp_socket_tx != -1) {
108.             ESP_LOGI("UDP", "Shutting down socket and restarting...");
109.             shutdown(udp_socket_tx, 0);
110.             close(udp_socket_tx);
111.         }
112.     }
113.     ESP_LOGE("UDP", "leaving task");
114.     vTaskDelay(200 / portTICK_PERIOD_MS);
115.     vTaskDelete(NULL);
116. };
117.  

GeSHi © Codebox Plus Extension

As global defines I have

#define WIFI_IP_ADDR "192.168.1.1"
#define UDP_SENDER_ADDR WIFI_IP_ADDR
#define UDP_RECEIVER_ADDR INADDR_BROADCAST

#define UDP_SENDER_PORT 3001
#define UDP_RECEIVER_PORT 3000

I have other tasks running in parallel, everything on one core.

Does anyone have an idea why I do not receive any UDP messages on my computer before I send a single message to the ESP32?

Am I missing out on starting something, is something not configured or needs to be woken up?

I searched the internet for hours, updated ESP IDP, the terminal program, alas, no success.
I appreciate you taking the time to read this, check the code and hopefully come back with an solution.

The code is based on various examples. As I do not read and messages from the connected station (computer), I do not use the receive section. It is not checked or cleaned in any way.

Kind regards
Greetings from Germany
Georg

[GvTardy]

Hi to everybody reading,

I fiddled more with my code and got is solved tonight, but I do not understand why.

I will post the complete code tomorrow with comments. It is getting late tonight, so my apologies for not doing so right away.

Very kind regards
Georg

[GvTardy]

Dear all,

unfortunately I have to revise my last nights reply.

If I give the ESP32 a full power cycle (not just make monitor), the connection to the terminal will not work prior to sending a message (e.q "1") to the ESP.

I corrected/cleaned the code a bit and post it again here.

Does anyone have a clue why is behaves like this:
- start the ESP -> it initializes the TCPIP connection with the ESP in softAP mode
- it waits for a computer/station to connect
- my connecting computer has the UDP terminal already started and setup upon connecting to the AP
- in the serial monitor I get messages that the UDP client has sent a UDP message, but nothing arrives in my terminal
- after sending any message (1 character) I receive the UDP messages from the ESP

I would like to receive the messages without sending a something from the UDP server (my laptop) first.

Kind regards
Georg

P.S. attached the code, I omitted the routine calling WIFI_AP_init(). This is the entry point.

Code: [Select all] [Expand/Collapse]

1.  
2. #include "freertos/FreeRTOS.h"
3. #include "freertos/event_groups.h"
4. #include "freertos/task.h"
5. #include "freertos/semphr.h"
6.  
7. #include "esp_system.h"
8. #include "esp_wifi.h"
9. #include "esp_event_loop.h"
10. #include "esp_err.h"
11. #include "esp_log.h"
12.  
13. #include "tcpip_adapter.h"
14.  
15. #include "lwip/err.h"
16. #include "lwip/sockets.h"
17. #include "lwip/sys.h"
18. #include "lwip/netdb.h"
19.  
20. #include "wifi_ap.h"
21. #include "udp_client.h"
22. #include "parameters.h"
23.  
24. #define AP_SSID WIFI_SSID
25. #define AP_PASSPHARSE WIFI_PSWD
26. #define AP_SSID_HIDDEN 0
27. #define AP_MAX_CONNECTIONS 1
28. #define AP_AUTHMODE WIFI_AUTH_WPA2_PSK // the passpharese should be atleast 8 chars long
29. #define AP_BEACON_INTERVAL 100 // in milli seconds
30. #define LISTENQ 2
31.  
32. #define WIFI_CONFIG_IPV4
33. #define WIFI_SSID "eBOARD"
34. #define WIFI_PSWD ""
35. #define WIFI_IP_ADDR "192.168.1.1"  // own address
36. #define WIFI_AP_MAX_STA_CONN 2
37.  
38. //#define UDP_SEND_WAIT_FOR_REPLY
39. #define UDP_SENDER_ADDR WIFI_IP_ADDR
40. #define UDP_SENDER_PORT 3001
41. #define UDP_RECEIVER_ADDR "192.168.1.2"  
42. #define UDP_RECEIVER_PORT 3000
43.  
44. //**********************************************************************************
45.  
46. int udp_socket_tx;
47. int udp_socket_rx;
48. struct sockaddr_in udp_sender;
49. struct sockaddr_in udp_receiver;
50.  
51. EventGroupHandle_t wifi_event_group;
52. const int AP_STARTED_BIT = BIT0;
53. const int STA_CONNECTED_BIT = BIT1;
54. const int STA_DISCONNECTED_BIT = BIT2;
55. const int UDP_SOCKED_BINDING = BIT3;
56.  
57. static esp_err_t event_handler(void *ctx, system_event_t *event)
58. {
59.     switch(event->event_id) {
60.     case SYSTEM_EVENT_AP_START:
61.         ESP_LOGI("WIFI_AP","ESP32 is started in AP mode");
62.         xEventGroupSetBits(wifi_event_group, AP_STARTED_BIT);
63.         break;
64.        
65.     case SYSTEM_EVENT_AP_STACONNECTED:
66.         ESP_LOGI("WIFI_AP", "station:"MACSTR" join, AID=%d",
67.                  MAC2STR(event->event_info.sta_connected.mac),
68.                  event->event_info.sta_connected.aid);
69.         xEventGroupSetBits(wifi_event_group, STA_CONNECTED_BIT);
70.         esp_wifi_set_ps(WIFI_PS_NONE);
71.         break;
72.  
73.     case SYSTEM_EVENT_AP_STADISCONNECTED:
74.         ESP_LOGI("WIFI_AP", "station:"MACSTR"leave, AID=%d",
75.                  MAC2STR(event->event_info.sta_disconnected.mac),
76.                  event->event_info.sta_disconnected.aid);
77.         xEventGroupSetBits(wifi_event_group, STA_DISCONNECTED_BIT);
78.         break;     
79.     default:
80.         break;
81.     }
82.     return ESP_OK;
83. }
84.  
85. void DHCP_server_init(){
86.    
87.     // initialize the tcp stack
88.     tcpip_adapter_init();
89.     // stop DHCP server
90.     ESP_ERROR_CHECK(tcpip_adapter_dhcps_stop(TCPIP_ADAPTER_IF_AP));
91.     // assign a static IP to the network interface
92.     tcpip_adapter_ip_info_t info;
93.     memset(&info, 0, sizeof(info));    
94.     info.ip.addr = inet_addr(WIFI_IP_ADDR);
95.     info.gw.addr = inet_addr(WIFI_IP_ADDR);
96.  
97.     IP4_ADDR(&info.netmask, 255, 255, 255, 0);
98.     ESP_ERROR_CHECK(tcpip_adapter_set_ip_info(TCPIP_ADAPTER_IF_AP, &info));
99.     // start the DHCP server  
100.     ESP_ERROR_CHECK(tcpip_adapter_dhcps_start(TCPIP_ADAPTER_IF_AP));
101.     printf("DHCP server started \n");
102. }
103.  
104. void WIFI_AP_init(void)
105. {
106.  
107.     ESP_ERROR_CHECK( esp_event_loop_init(event_handler, NULL) );
108.     wifi_event_group = xEventGroupCreate();
109.     DHCP_server_init();
110.    
111.     //xTaskCreate(&tcp_server,"tcp_server",4096,NULL,5,NULL);
112.     esp_log_level_set("wifi", ESP_LOG_NONE); // disable wifi driver logging
113.     wifi_init_config_t cfg = WIFI_INIT_CONFIG_DEFAULT();
114.     ESP_ERROR_CHECK( esp_wifi_init(&cfg) );
115.     ESP_ERROR_CHECK( esp_wifi_set_storage(WIFI_STORAGE_RAM));
116.     ESP_ERROR_CHECK( esp_wifi_set_mode(WIFI_MODE_AP) );
117.  
118.     // configure the wifi connection and start the interface
119.     wifi_config_t ap_config = {
120.         .ap = {
121.             .ssid = AP_SSID,
122.             .password = AP_PASSPHARSE,
123.             .ssid_len = strlen(AP_SSID),
124.             .channel = 0,
125.             .authmode = AP_AUTHMODE,
126.             .ssid_hidden = AP_SSID_HIDDEN,
127.             .max_connection = AP_MAX_CONNECTIONS,
128.             .beacon_interval = AP_BEACON_INTERVAL,         
129.         },
130.     };
131.  
132.     if (strlen(WIFI_PSWD)==0)
133.         ap_config.ap.authmode = WIFI_AUTH_OPEN;
134.  
135.     ESP_ERROR_CHECK(esp_wifi_set_config(WIFI_IF_AP, &ap_config));
136.     ESP_ERROR_CHECK( esp_wifi_start() );
137.     printf("ESP WiFi started in AP mode \n");
138.  
139.     xTaskCreate(&task_UDP_client, "UDP", 4096, NULL, 5, NULL);
140. }
141.  
142. //**********************************************************************************
143. //***  UDP socket ******************************************************************
144. //**********************************************************************************
145.  
146. void task_UDP_client(void *pvParameters)
147. {
148.     uint16_t cnt = 0;
149.     char rx_buffer[128];
150.     char addr_str[128];
151.     int addr_family;
152.     int ip_protocol;
153.  
154.     while (1) {
155.  
156.         ESP_LOGI("WIFI","Waiting for Station");
157.  
158.         EventBits_t staBits = xEventGroupWaitBits(wifi_event_group, STA_CONNECTED_BIT, pdTRUE, pdFALSE, portMAX_DELAY);
159.  
160.         if((staBits & STA_CONNECTED_BIT) != 0)
161.             ESP_LOGI("UDP","Connected, starting UDP_Client\n");
162.         else {
163.             ESP_LOGI("UDP", "timeout waiting for connection...");
164.             break;
165.         };
166.  
167.         udp_socket_tx = socket(PF_INET, SOCK_DGRAM, IPPROTO_IP);
168.  
169.         if (udp_socket_tx < 0) {
170.             ESP_LOGE("UDP", "Unable to create socket: errno %d", errno);
171.             xEventGroupClearBits(wifi_event_group, UDP_SOCKED_BINDING);
172.             break;
173.         }
174.         else{
175.             ESP_LOGI("UDP", "Socket created");
176.             xEventGroupSetBits(wifi_event_group, UDP_SOCKED_BINDING);
177.         };
178.  
179.  
180.         udp_sender.sin_family = AF_INET;
181.         udp_sender.sin_addr.s_addr = inet_addr(UDP_SENDER_ADDR);
182.         udp_sender.sin_port = htons(UDP_SENDER_PORT);
183.  
184.         if(bind(udp_socket_tx, (struct sockaddr *)&udp_sender, sizeof(struct sockaddr_in)) == -1) {
185.             ESP_LOGE("UDP", "bind failed");
186.             close (udp_socket_tx);
187.             exit(1);
188.         }
189.         else
190.             ESP_LOGI("UDP", "bind created");
191.  
192.         udp_receiver.sin_family = AF_INET;
193.         udp_receiver.sin_addr.s_addr = inet_addr(UDP_RECEIVER_ADDR);
194.         udp_receiver.sin_port = htons(UDP_RECEIVER_PORT);
195.  
196.         while (1) {
197.  
198.             static const char *msg = "test UDP send \n";
199.  
200.             vTaskDelay(2000 / portTICK_PERIOD_MS);
201.  
202.             cnt++;
203.  
204.             int err = UDP_send("UDP: msg no %d", cnt);
205.  
206.             if (err < 0) {
207.                 ESP_LOGE("UDP", "Error occured during sending: errno %d", errno);
208.                 break;
209.             }
210.             else
211.                 ESP_LOGI("UDP","send to %s ",  ip4addr_ntoa(&(udp_receiver.sin_addr)));
212.  
213.         }
214.  
215.         if (udp_socket_tx != -1) {
216.             ESP_LOGI("UDP", "Shutting down socket and restarting...");
217.             shutdown(udp_socket_tx, 0);
218.             close(udp_socket_tx);
219.         }
220.     }
221.     ESP_LOGE("UDP", "leaving task");
222.     vTaskDelay(200 / portTICK_PERIOD_MS);
223.     vTaskDelete(NULL);
224. };
225.  
226. esp_err_t UDP_send(const char *fmt, ...){
227.     char text[128];
228.     esp_err_t err = ESP_OK;
229.  
230.     va_list arg_ptr;
231.     va_start(arg_ptr, fmt);
232.         vsnprintf(&text[0],sizeof(text), fmt, arg_ptr);
233.     va_end(arg_ptr);
234.  
235.     EventBits_t staBits = xEventGroupGetBits(wifi_event_group);
236.    
237.     if((staBits & UDP_SOCKED_BINDING) != 0) {           // socket is bound
238.         err = sendto(udp_socket_tx, text, strlen(text), 0, (struct sockaddr *)&udp_receiver, sizeof(udp_receiver));
239.     };
240.  
241.     return err;
242.  
243. };

GeSHi © Codebox Plus Extension

[GvTardy]

Hello everyone,

I installed Wireshark to monitor the UDP traffic. Interesting finding:

The ESP32 does start sending messages as soon as the station (my Laptop) has connected.

BUT: non of my terminal programs starts displaying these messages before I send a line to the ESP32
(Hercules, YAT, script commander)

I have no clue why the terminal programs start displaying messages after sending a line. Is this related to the terminals, is this a driver issue (windows 10)? Related to the Firewall...

I have not found a practical workaround yet.

So, the issue has not been solved but it is not on the side of the ESP32.

I would be very if anybody had an idea how I can log the UDP messages by just opening a logger.

Kind regards
Georg

[GvTardy]

Firewall !!!

I missed a specific setting for public, non protected networks...

Alas, a stupid way to burn so much time, but at least it's working now.

Greetings
Georg