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I am using an stm32f2xx-series controller in my project. I want to know whether an external flash is connected to the micro-controller or not without doing any read/write operations to the external flash. Is that possible?
If yes, please explain the means to do so.
If it matters, communication between the controller and the external flash is SPI.
Thanks in advance.
I can't think of any way your firmware can detect the presence of an SPI device without talking to it. Reading a status or device identification register is how you typically probe for it.
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I know my question is broad, but I have no clue where to start my research.
How can one implement VoIP on a server? I am fairly certain it does not use the http/https protocol. If so, what standard/famous protocols one can use? are there any open-source ones? What are good references to start working on that?
Start by looking at the SIP,RTP and RTCP protocols. I believe they form a minimalistic set of required protocols for VoiP
Some relevant open source projects:
http://www.fsf.org/campaigns/priority-projects/priority-projects/highpriorityprojects#Replaceskype
"There are a number of such programs, such as Ekiga, Twinkle, Coccinella, QuteCom, and Jitsi. Unfortunately, these programs only replace some of Skype's functionality, and only in some situations. WebRTC has a mission to enable rich, high quality, Real-Time Communications (RTC) applications to be developed in the browser via simple Javascript APIs and HTML5. Developers should consider helping free software VoIP and video, chat, and multimedia communications projects."
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I have got telnet server running on a bsd target. I want to connect to this target from multiple other machines. Surprisingly it does not allow more connections.
I checked why and found it is not listening(listen) in a loop. So, I kinda fixed it. But I was wondering is there any specific reason why telnetd code is kept with single connection at a time? (I am allowed to connect to telnetd server from only one client for a particular port.)
(I know telnet is not a safe option. But I am having just fun on small embedded platform and getting things working is more imp than security at this moment.)
Thanks
Telnet is supposed to be launched by inetd. You need to configure inetd to do the listening for you.
The wikipedia article that I linked to explains how to do that.
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I would like to have a database store of user statuses, as they come online/offline/afk. Can ejabberd store status changes to a database?
This feature is not provided as a default in ejabberd, because it does not scale out of the box. This is the reason ejabberd has kept a very low latency and improve the real time nature of XMPP.
It doesn't appear that ejabberd comes with this functionality baked in, but it's possible to achieve something close enough, several different ways - I believe the standard method is to create a component.
Ejabberd is maintaining the presence status of users internally. Its the main feature of the XMPP protocol as the name suggests Presence protocol. To store it on the database and than handle it means delay in request/response and it will not be the real-time operation.
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I read about OpenBTS it's really amazing... but I was wondering if we can use it to build phone-to-phone provider-less network.
Any clues or experiments are really appreciated.
One thing to be aware of is that open BTS is 2G/GSM only - i.e. it does not support 3G/UMTS.
This may or may not be important to you depending on what you would like to achieve.
There does appear to be some discussion on adding this functionality in the future (i.e. building an open node b/RNC effectively) but it will be tricky as the authentication mechanism used in 3G requires the network owning the SIM to provide authentication data for even the most basic communication.
GSM follows a strict client-server model. Mobile phones are intended to be clients.
If you would want to build phones with phone-to-phone capability you would need to implement network functionality in the phone. With this, phone-to-phone (theoretically) could be done in an ad-hoc-network model, with one phone running the network part.
I would suspect that one has to look at impacts on the pyhsical/radio layer as well.
Rather unrealistic, IMHO.
May be of interest:
http://terranet.se/history/
So far this company (TerraNet) seem to be only offering sowftware for creating mesh networks over Wifi (I think Wifi is a big disadvantage due to the battery drain. If only we could use GSM), but they seem to share this idea.
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Can somebody please explain connection pooling to me please?
I am just not understanding it by searching the internet.
please read this:
http://msdn.microsoft.com/en-us/library/8xx3tyca.aspx
http://www.15seconds.com/issue/970531.htm
this could be also very helpful..- (:
It is layer that handles connections. Instead of opening and handling connection from your application,
This way you say
gimme_connection
and you get the connection becuase it was allready opened or if needed it is reopened. This is usefull for databases where there are lot of "processes" who need connections on same address.