Re: [lwip-users] how to send udp messages circularly ?

[address@hidden]

the_gadfly wrote:
> [...]
> int count=0;
> void Delay(unsigned long ulVal)
> {
> while ( --ulVal != 0 );
>   

Any good compiler will optimize this away to nothing, I guess. If you 
really want to delay like that, you'd have to use a volatile variable.

> }
> void
> httpd_init(void)
>   

From where (which thread, what point, e.g. after stack initialization?) 
do you call httpd_init()? This whole thing could be a threading problem: 
a mistake that many lwIP beginners make is to use the raw API from 
multiple threads - it may only be used from the tcpip_thread and not 
from interrupt level!

> {
> struct udp_pcb *pcb;
> struct ip_addr PCipaddr;
> struct pbuf *p,*pbuffer;
> err_t err;
>
> IP4_ADDR(&PCipaddr,10,1,1,52);
>
> p = pbuf_alloc(PBUF_RAW,sizeof(Test),PBUF_RAM);
> p->payload=(void *)Test;
>   

Like Kieran already indicated: the above 2 lines are totally wrong usage 
of the pbuf API:
- PBUF_RAW means NO additional headers whereas you want to send a UDP 
packet which means there will have to be UDP, IP and ARP headers added. 
Use PBUF_TRANSPORT for sending UDP data.
- When allocating a PBUF_RAM, you get one continous region of memory: 
struct pbuf is at the beginning, the data buffer follows. For PBUF_RAM 
pbufs you *must not* mess with the payload pointer! Instead, copy the 
data from the original location into the pbuf using memcpy(p->payload, 
src, len); if you want to do it like you did (p->payload = x), use 
PBUF_REF instead of PBUF_RAM or lwIP might even corrupt your RAM by 
writing to places it shouldn't.

> pbuffer = pbuf_alloc(PBUF_RAW,sizeof(Test1),PBUF_RAM);
> pbuffer->payload=(void *)Test1;
>
>
>
> pcb = udp_new();
> err=udp_bind(pcb, IP_ADDR_ANY,60000);
> if(err==ERR_OK)
> {printf("bound ok ! \n");}
> err=udp_connect(pcb,&PCipaddr,60000);
> if(err==ERR_OK)
> {printf("connect ok !\n");}
> while( count++ < 20 ) 
> {
>
>
> err=udp_send(pcb,p);
> if(err==ERR_OK)
> { printf("udp_send OK \n"); }
> //Delay(1000000);
> // Delay(1000000);
> // Delay(1000000);
> // err=udp_send(pcb,pbuffer);
>
> }
>
> }

This may be stupid, but did you check err == ERR_OK in all places, e.g. 
did you see the printf's?
If all this didn't help, it could still be that your MAC or OS port has 
a bug...

Simon