ESP8266 Community Forum

Posted: **Sun Mar 20, 2016 3:55 am**

Hello,

I want to send DHCP discovery messages with the ESP8266 manually.
I have made the following code:

#define UDP_BROADCAST_PORT 3444
char DeviceBuffer[40] = {0};

wifi_set_opmode(STATION_MODE);
wifi_station_dhcpc_stop();

myEspconn.type = ESPCONN_UDP;
myEspconn.state = ESPCONN_NONE;
myEspconn.proto.udp->remote_port = UDP_BROADCAST_PORT; // ESP8266 udp remote port
myEspconn.proto.udp->local_port = UDP_BROADCAST_PORT; // ESP8266 udp local port

remote_ip = IPADDR_NONE;
os_memcpy(myEspconn.proto.udp->remote_ip, &remote_ip, 4);

wifi_get_macaddr(STATION_IF, hwaddr);
os_sprintf(DeviceBuffer, "%s" MACSTR "!", ESP8266_MSG, MAC2STR(hwaddr));
espconn_send(&myEspconn, DeviceBuffer, os_strlen(DeviceBuffer));

Espconn_send is returning error-code -4.

Could somebody help me and explain what could be wrong here.

Best regards,

Wamor

Posted: **Sun Mar 20, 2016 4:10 pm**

Ok, found the first bug. I need to fill the DeviceBuffer with DHCP discovery data. Done this now.
Still when I stop automatic dhcp of the module and set source address to: 0.0.0.0 I got error -4 when executing espconn_send(). Should not this be possible because when sending DHCP discovery packages one should set the source address to 0.0.0.0 and the destination address to 255.255.255.255.

ESP8266 Community Forum

Manually sending DHCP discover messages

Manually sending DHCP discover messages

Re: Manually sending DHCP discover messages