+IPD maximal number of data bytes

tilz0R
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+IPD maximal number of data bytes

Postby tilz0R » Sun Jan 03, 2016 6:56 am

Hi,

I'm using extended IPD statement with IP and PORT when data are available.

My question is, how to limit maximal number of bytes inside IPD statement?
When I'm trying retrieve data from server as client where response has together about 20k of data, in most cases, I got 1452 bytes packet size in 1 IPD and then a lot of these statements.

Sometimes, (I can't figure in what cases), I get 5092 bytes long IPD which is too big for my internal buffer.

How to make fix limit?

ESP_Faye
Posts: 1646
Joined: Mon Oct 27, 2014 11:08 am

Re: +IPD maximal number of data bytes

Postby ESP_Faye » Mon Jan 04, 2016 10:50 am

Hi,

Sorry that we can not limit the +IPD maximal number, it is followed by the data received from network, for TCP connection, it can be 4x1460 bytes at most.

Thanks for your interest in ESP8266 !

tilz0R
Posts: 38
Joined: Sat Dec 26, 2015 8:36 pm
Contact:

Re: +IPD maximal number of data bytes

Postby tilz0R » Mon Jan 04, 2016 6:02 pm

I'm not trying to be silly, but as far I know, LWIP always have data packets of fixed size, never more than 1518 bytes with headers included. If more data are available, there are more packets linked together on separate memory address. So I think, you can for each linked packet send +IPD command separate.

In other case, this is veeery too much data for one small 2K of ram MCU.

Have a nice day.

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