topic Re: Problems with double messages on the 52235! in ColdFire/68K Microcontrollers and Processors

Problems with double messages on the 52235!

J_karlsson — Thu, 12 Oct 2006 21:27:01 GMT

Hi, I'm using the code supplied by freescale for using the Ethernet interface on the MCF52235. I've ported the OpenTCP stack from the MC9S12NE64 to the MCF52235 and it work fine except for one problem. When i use the eth_stub_send() function the message is always sent twice! But I'm sure the function is only called once. I noticed that a few other people on the forum had the same problem. Does anyone know what might be causing this?

Best Regards

Johnny Karlsson

Re: Problems with double messages on the 52235!

DrSeuss — Thu, 19 Oct 2006 11:06:25 GMT

TCP is an ack/nak protocol. Meaning that all packets must be acknowledged in a certain time. I'm sure all stacks have a setting for this timeout and perhaps if you are using any stack release by me (I will not advertise which company work for) these setting might be too small. (i have seen this too, but only on my home wireless)

Also try turning off encryption on your net (wep). This might also cause delayed responses and hence the second transmission.

I wish I had more time to investigate this, so pls try and post your findings.

Re: Problems with double messages on the 52235!

J_karlsson — Thu, 19 Oct 2006 22:28:42 GMT

Hi, thanks for your suggestions. But I have implemented the OpenTCP port on top of the MAC-layer code that freescale provides. And i put a breakpoint on eth_stub_send function (which is a MAC-layer function) and it only gets called once from the stack. But still the ethernet controller sends dual messages. So the problem must be at the MAC-layer.

Re: Problems with double messages on the 52235!

ras — Fri, 22 Dec 2006 05:17:46 GMT

Did you find any solution for the double packet retansmission problem of the openTCP?

We have the same problem and I will appriciate if you can help

Re: Problems with double messages on the 52235!

J_karlsson — Fri, 22 Dec 2006 15:11:40 GMT

Hi, apparently this problem occurs if you only have one send buffer in n-buf. If you increase the number two to ore more the problem goes away. This is also advisable for the receive buffer. I haven't tried this myself since though, so let me know how it goes.

Best Regards

Johnny Karlsson

Re: Problems with double messages on the 52235!

UDP — Sun, 24 Dec 2006 16:42:55 GMT

Hello

Where exactly do i need to add the buffer in the code ?

Can you add an example ?

Thanks