[En-Nut-Discussion] Status of Point-To-Point protocol over RS-232

[Harald Kipp]

Hi Nathan,

On 4/17/2011 2:40 AM, Nathan Moore wrote:
> A year or two ago I did some work adding support for another network
> device that also used a serial port and AHDLC
> to a custom Nut/OS version for the company I worked for at the time.

Many thanks for sharing this information and your effort to provide a 
patch. I'm not sure if this should go to 4.8 (may break existing stuff), 
so I committed it to the trunk only. Provided for 4.8, it didn't exactly 
fit and also contained minor typos. That was fixed in a few minutes, but 
saved me hours of research as well as a significant amount of code 
space. So far I tested avr-gcc only, using Ethernut 2. Everything is 
working fine and I updated

http://www.ethernut.de/en/documents/ntn-1_ppp.html

Andras sent at91_ahdlc.c again. I haven't yet checked, whether this is a 
newer version, but he claims, that it does not depend on DMA and should 
be easily adapted to different ARM variants. Many thanks to him too. 
I'll keep you informed about my results.

Just for the records:

> +    case HDLC_SETTXACCM:
> +        dcb->dcb_tx_accm = (*lvp)
> +        break;

Oops! Missing something? :-)

> -    dcb->dcb_rx_buf = NutHeapAlloc(256);
> -    dcb->dcb_tx_buf = NutHeapAlloc(256);
> +    dcb->dcb_rx_buf = NutHeapAlloc(256 * 2);
> +    dcb->dcb_tx_buf = dcb->dcb_rx_buf + 256;

Won't work because of volatile specifier for rx_buf. Not sure, if this 
specifier makes sense at all, but I do not have the time right now to 
verify this.


Regards,

Harald