Re: [lwip-users] LWIP client code causes hard fault error

[shettys]

Thanks for this. 
I have not initialized the tcp_arg,tcp_sent & tcp_recv functions since i do
not use them , hence i think that there is no reason to 
add this in the code (   tcp_arg(pcbname, NULL); tcp_sent(pcbname, NULL);
tcp_recv(pcbname, NULL);. Please correct me if i am wrong.
Sometimes when i start the server and start the lwip client code(from my arm
cortex development board) it sends the data fine.
When i disconnect the connection and try reconnecting again immediately it
goes to a hard fault. Is it something to do with the timers?Thanks


Funk, Artur wrote:
> 
> When does it fails? While the first transfer or after several tries? If
> it fails after several calls of your sending function, the problem could
> be, that you don't free allocated memory or don't close the established
> connection proper. If it fails on first transfer, it could be a pointer
> reason. Your function seems to be incomplete isn't it?
> Here is an example to close the connection after sending
>    tcp_arg(pcbname, NULL);
>    tcp_sent(pcbname, NULL);
>    tcp_recv(pcbname, NULL);
> 
>    mem_free(data);
>    tcp_close(pcbname);
> 
> void TCP_send(void)
> {
>       uint32_t (*ptr)[3]; // pointer to the   ADC_TDstamped_SRAM
> array.
>       #ifdef UserButton_InteruptFor_ADCConversion
>       sprintf((char*)data, "Potentiometer value is, %d\n",
> ADC3ConvertedValue);
> 
>       /* allocate pbuf */
>       es->p_tx = pbuf_alloc(PBUF_TRANSPORT, strlen((char*)data) ,
> PBUF_POOL);
>          
>       if (es->p_tx)
>       {       
>      
>           /* copy data to pbuf */
>         pbuf_take(es->p_tx, (char*)data, strlen((char*)data));
>         
>         /* send data */
>               TCPData_send(pcb,es);
>       }
> }
> 
> What I can see is:
> uint32_t (*ptr)[3]; <- unused
> 
> sprintf((char*)data.... <- where is data dfined?
> 
> es->p_tx = pbuf_alloc(PBUF_TRANSPORT, strlen((char*)data)  <- are u sure
> the data is always null terminated?
> 
> 
> Note if you allocate each time new memory space for you data, don't
> forget to free the memory and to set the pointer to NULL.
> 
> I hope I can calm u down if I would say that such errors I have had in
> the past were based on my own mistakes and not on LwIP.
> 
> 
> 
> Best regards
> 
> 
> Artur
> 
> 
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> 
> 
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