where are the wifi shield parameters like "3000" documented?

BillhBillh
edited January 2018 in Wifi Shield
In the file OpenBCI_Python/open_bci_wifi.py, line 414, a comment states "# 3000 is the max data the WiFi shield is allowed to send over TCP." 

 It looks as if most such definitions are in OpenBCI_WIFI/src/OpenBCI_Wifi_Definitions.h, but the above 3000 byte limitation is not mentioned there.  This is for writing a TCP driver type routine for the WiFi shield.

Is there another file on github where other constants of this kind are documented?

Comments

  • wjcroftwjcroft Mount Shasta, CA
    Is there a particular constant or parameter you are most interested in? Some of these values might be limitations of the ESP8266 wifi chip at the heart of the Wifi Shield. And would be shown in the Expressif data sheet.


    Mentioning AJ @pushtheworld.
  • BillhBillh
    edited January 2018
    The python wifi shield driver sets up the data streaming and then hands the connection to an "asyncore" python module that I believe uses sockets rather than http. Some servers can keep a TCP connection open for streaming, and I was hoping that the WiFi shield could do that kind of transfer. I was wondering if that 3000 byte limit would prevent HTTP streaming, but if it's just the limit on the ESP8266 MTU size that would be fine.

  • wjcroftwjcroft Mount Shasta, CA
    This search on the MTU size seems to turn up different values. It could be that with the latest firmware, it's now 3000.


    OR

  • pushtheworldpushtheworld
    Okay so a couple things:

    The largest amount of data the wifi shield can send is 1440 and that's from the ESP8266 upper limit. That's 42 raw packets per TCP send. The TCP on the wifi shield acts as a client for high speed streaming. The asyncore uses TCP as far as i knoe, it's a raw socket, not a web socket.

    The firmware is a great place or the learning pages under software! http://docs.openbci.com/OpenBCI Software/03-OpenBCI_Wifi_Server

    Good luck!
  • pushtheworldpushtheworld
    @Billh or @wjcroft

    Any ideas on where I should document the hard contstants for future users?
  • BillhBillh
    Maybe under Hardware in the Data Format pages? Or wherever you think it fits in.

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