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I interested in CAN HW object.
I aware of CAN Acceptance filter that in change of CAN ID filtering.
why CAN hardware acceptance filter present in receive?
When CAN message received, is CAN arbitration procedure excuted?
When CAN Message transmitted, Is CAN arbitration unnecessary?
Acceptance filters are used to filter received CAN messages according to their IDs, so that the firmware is not interrupted by the messages which it isn't interested in. Filters are applied after the hardware receives the message. If the message can't pass any filter, it's discarded. This prevents unnecessary hardware interrupts.
TX side doesn't need any filters, because the firmware designer chooses what to send.
Each node executes the CAN arbitration procedure during transmit, by sampling the bus as it transmits. If the transmitting node looses the arbitration, it stops transmitting to try again later.
Nodes on the bus receive only the messages that won the arbitration. Arbitration process is an essential & embedded part of the CAN protocol and it's always there and necessary.
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When Bus off state occurs, assume because of failure of can controller in one node, then how other nodes will come to know that the bus is in off state?
Can anybody aware of this?
Bus off simply means that the current node stops sending information on the bus. Not necessarily that "the whole bus is off", though of course if there's some physical problem with the bus, then all nodes will end up in "bus off" state.
Other nodes will only notice this when a particular node stops responding and not doing ACK. Usually higher layer protocols have mechanisms for checking this, like for example the "Heartbeat" feature of CANopen.
For general CAN bus error handling see this: https://www.kvaser.com/about-can/the-can-protocol/can-error-handling/
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We are looking for the ways to handle data transfer using audio jack in iOS.
We searched a lot to see whether it is possible to have this two way data communication through iPhone's audio jack, but had no luck yet. As per mentioned in some forums its possible, but again ended up with kind of vague answers which are more of theoretical-
Receiving Data Through Audio Jack
Force iPhone to read in data through headphone jack
http://hackaday.com/2010/02/01/android-audio-serial-connection/
So far we understand the app needs to be able to perform below things:
Check whether audio jack is ready to transfer the data with cable is already inserted into it
Sending Data : Data on your iPhone should be converted into analogue signals as you are going to transfer it using audio connector.
Receiving Data : Data will be received as analogue signals which should be converted to digital to read it back.
Please correct me or add up if anything is missing. Also wanted to ensure whether direct communication is possible. Ex. If I want to transfer data from my iPhone to Mac machine. Do we need to have dependency over any middleware hardware which then handles the signal conversion.
It would be really great if anyone is aware of any available 'libraries / APIs / well-defined process' which can be good enough to make a start..
Any help in this regard will be greatly appreciated!
Thanks.
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I am trying to build a IVR system, where the IVR will receive the dial tones from user and reads messages from the database based on the dial tones. I am fairly new in this kind of matter and i have researched about solutions like asterisk but i would like to have detailed information on how to setup this system. I have the simple PSTN RJ-11 line in my office and the customer would dial the number of this line to get connected with the IVR system.
What are the hardware required and how will they be connected?
Is it possible to accept multiple calls?
To accept multiple incoming calls in parallel you need either multiple individual lines from your service provider or a 'trunk' connection (either traditional digital trunk or an IP based SIP trunk).
There are quite a few good detailed Asterix IVR guides - some links from an answer to a similar question are:
http://www.asterisk.org/get-started/applications/ivr
http://www.freepbx.org/support/documentation/administration-guide/creating-an-ivr
setup an IVR with Asterisk
On the hardware side, it depends what connection you end up getting from your service provider, but you will need some sort of line card to terminate the telephony if it is traditional analogue or digital. See this Asterix page for more information:
http://www.asterisk.org/products/telephony-interface-cards
Note that your service provider (or an alternative provider in your area) may be able to provide you SIP / IP based 'trunks' in which case you would not need this extra hardware. It might be worth checking this out depending on your specific requirements and the price etc.
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I'm trying to learn the ins and outs of an 8237A-5 DMA controller. I've been reading about it and now I've started to design it at the gate level in software. The CS pin is active low. If it gets a high signal on here, do what happens? Do all the other pins just go to high Z? What happens when it gets a low signal?
The data outputs go high impedance to allow other chips to use the data bus -- any operations that occur on the bus are ignored. When it gets a low signal on the CS pin, it will process any bus transactions it sees according to its data sheet. It will then latch the data from the data bus or drive data onto the data bus for a read or write cycle respectively.
The usual hardware design is the CS pin is driven by the output of the address decoder. When the address is seen to be in range for the target device, the address decoder drives that device's chip select pin active. That way, only the target device responds to each bus operation.
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I'm not sure, if it's the right place here to ask this question.
But can anybody explain more detaild, how sim-based mobile phone tracking's working, und if it costs anything (the second part is very important)?
The Wikipedia article explains it pretty well:
Mobile phone tracking tracks the current position of a mobile phone even on the move. To locate the phone, it must emit at least the roaming signal to contact the next nearby antenna tower, but the process does not require an active call. GSM localisation is then done by multilateration based on the signal strength to nearby antenna masts.
So as soon as your phone is turned on, it starts to emit signals that the antennas catch. If several of them receive the signal, that (and the signal strength) gives a pretty good indication of your location.
It needs a bit of software (which the law requires today), so it doesn't cost anything "extra" for the people that provide the hardware. It's not free for normal people to use, though.
sim based? mobile phone tracking goes in layers, just like PC. At first GPS, if phone don't have it then it counts what mobile providers towers covers the phone and how strong mobile signal is from each tower, so by that it can counts you location. It Don't cost for telephone companies but it might for you since it depends on connection provided by towers. So its not the thing you can do without providers knowing it.