I'm deciding between the MiniPCIe and USB accelerators for a home Linux CCTV project. The host has both USB3 and a MiniPCIe socket. The host's physical environment will range from an ambient 20C up to a potential 35C (during the summer).
I'm struggling to determine the pros and cons for each. I have gotten this far, although many are guesses:
USB:
Supports Windows and MacOS as well as Linux
Appears to have greater mindshare/use/community support on the Internet
External so can be placed to optimise heat dissipation
Heatsink
Two manual performance modes, highest requires ambient temp of max 25C
Can use up to 4.5W (900mA # 5V)
Mini PCie:
Cheaper (25%)
Lower power consumption (1.4W for 416 fps)
Automatic thermal throttling via driver
Relies on host system for active cooling
Will maintain max operation at 85C
There's probably many I've missed. In particular I can't determine if there's any limitations on throughput/capacity using USB vs PCIe. If there is no difference, then I suspect the USB form factor is the better option, if only for the mindshare, although the power usage/heat generated may be a concern.
To whittle this down to an actual question: in what cases would the Mini PCIe interace be a preferred option to the USB one?
If you are looking for a plug&play solution, then I definitely suggest the USB Accelerator. Overall, as long as you have the system requirements then it'll always works (maybe with some modifications to the standard linux configs like adding your user to the plugdev group, ...). Then the software for the CCTV is all up to you :)
PCIes sometimes need extra works like adding extra kernel arguments and modules to keep the pcie modules happy. If you are looking to launch a huge product where volumes are expected, then it is worth investigating it since it's cheaper and more compact. However, the power usage is a must for consideration as the USB Accelerator could uses up to 900mA, so that could play a factor.
May I know what host are you trying to attach the accelerators to?
Related
Assume there is an MCU(like a cypress PSOC4 chip which I'm using). It contains a flash memory(to store firmware) and a RAM(probably SRAM) inside the chip. I understand that even these two components need to be memory mapped in order for the processing unit to access them.
However, the flash memory and SRAM should be mapped every time the MPU is powered on, right?.
Then where is the configuration for memory map stored?
Is it somehow hardwired inside the MPU? Or is it stored in a separately hidden small piece of RAM?
I once thought that the memory map info should be located at the front of the firmware, but this doesn't make sense because the firmware is stored in the flash, and the MPU would have no idea where the flash is mapped to. So, I think this is a wrong idea.
By the way, is a memory map even configurable?
Yes hardwired in the mcu on boot, some mcus allow for remapping once up and running, but in order to boot the flash/rom has to be mapped to a known place, a sane design would also have the on chip sram mapped and ready to use on boot at a known location.
Some use straps (pins externally hardwired high or low) to manipulate how the mcu boots, sometimes that includes a different mapping. A single strap could for example choose between mapping a bootloader rom vs the user flash into the boot space of the processor. But that would be documented as with other mapping choices in the chip vendors documentation for the part.
Some mcus allow you to in software after boot move ram into the vector/exception table area so you can manipulate it at run time and not be limited to what was in the flash at boot. Some mcus are going so far as to have a mmu like feature, but I have a hard time calling those mcus as they can run in the hundreds of mhz, have floating point uints, caches, etc. Technically they are a SOC with ram and flash on chip, so classified as an MCU.
Your thinking is sane, the flash and sram mappings are in logic and at reset you can know where things will be. It is in the documentation for that product.
I want to create a network intrusion detection system for iOS application. The main function is to allow the user to select a home network (maybe prompt them to simply enter the IP address only) and to be able to monitor the packets and if there is anything suspicious- we need to alert user via push notification or email. i wanted to use the features and functions of Snort, an open source network intrusion detection system.
Any Suggestions,Sample code ?! Where to start?
VM's do not have native hardware access, which is necessary for monitor mode. Maybe IOMMU PCI passthrough or bridged devices might work. It is probable that it is possible to compile the iOS kernel with a module that works for the wireless nic. I don't think it's a proprietary chip specific to apple, because a chip with multie technology capabilities in RF wouldn't be cost effective qt all. I'm just not sure if the filesystem blocks access in the OS framework or whatever. I have tried to compile linux/iOS ARM packages natively in the shell with the aircrack-ng source, but have not had any luck. Maybe someone would have better luck actually cross-compiling a package and sideloading it somehow.
I don't think this is possible for multiple reasons:
You wouldn't be able to compile snort for iOS.
In order to run snort you have to have the interface (NIC) in promiscuous mode, which I really don't think you can do on an iOS device (iPhone, iPad, etc) but I have never really looked into it, but Apple probably locks this down and restricts this for security purposes so if you could do it you'd likely have to jail-break the device first. It's not even possible to put the wifi card in an Apple laptop into monitor mode, which is similar.
There are a lot of dependencies for snort, most importantly the DAQ. You would probably only be able to monitor the wifi interface (even this might not be possible), not the interface used for the cellular network as this is probably a different daq than standard Ethernet nics.
This very likely is not possible on iOS, if it is it would be VERY difficult to pull off and even if you did the use case isn't really good. Even if you could get a daq for the cellular card, I don't know if promiscuous mode even exists and if it did all of the traffic on the cellular network is encrypted, so inspecting this with snort would be pointless. If you could do it for the wifi traffic it's probably not worth the effort honestly, especially since almost all traffic nowadays is encrypted, you'd have to decrypt it first, which certainly isn't possible to do.
In the view of Johnjg12's comments, I am wondering about your goal. If you want to make a NIDS, you can make it OS independent, anyway. If you want to consider only HIDS that monitors packet destined to it, we don't need it to be in promiscuous mode (a comment to Johgj12's response). so, now it is something to do with Snort on iOS. I am wondering if we can do it on a VM and then turning its promiscuous mode? Having said that I came across a link: https://www.securemac.com/macosxsnort.php
I’m doing a study project on wifi signal quality. What I want to do is use Raspberry Pi’s to monitor as many metrics as possible on packet level data. I want to do this by putting wifi adapters on monitor mode (using airmon-ng) and than capture the data about the packets using a wireless network protocol analyzer, like tshark.
What I understand from the wireless networks is that you mainly have three parts: a frame part that has the same information independent of what you’re capturing on, which contains things as frame number, frame length and arrival time. (Want to upload images but don't have 10 reputation yet...).
Then the IEEE 802.11 data which contains the necessary stuff for the network to work. When capturing on WLAN this contains the MAC addresses.
And than we have the radiotap header, which contains all kind of information (signal strength db and dbm, noise level, signal quality, TX value, and much more). This one is a bit different, since this information is actually filled or injected by the wifi adapter you use to capture the data with.
In the present flags you can find which values are actually being injected by the wifi adapter. Now my problem is that for my research I really need as much values as possible. I’ve been working for hours but I didn’t succeed in finding a way to capture with anything more than dmb signal strength (if even available). So this is what I tried so far:
The adapters I used so far are the Edimax EW7811UN, the AirPcap Classic, the AirPcap Tx and two similar alfa adapters with Atheros AR9271 chipset. The AR9271 adapters worked out of the box on raspbian (debian for raspberry pi) on the ath9k_htc driver. Putting them on monitor mode and capturing works fine, but only dbm singal strength is given (as in the screenshots above) in the capture. The Edimax was working out of the box on the 8192cu driver, however it clearly doesn’t support monitor mode. I could put it into monitor mode when booting it on the zd1211rw driver but that didn’t even give the dbm signal strength. Strange thing however, is that a friend tried the exact same Edimax adapter and he could capture, and the only difference we could find is that the lsmod says rtl8192cu and not 8192cu. Strangely, forums are saying that 8192cu is the newer version, however this friend had the newest arch linux kernel installed (newer than the raspbian). So I installed Arch Linux on the pi, but still wasn’t able to put the edimax on 8192cu driver in monitor mode. Then I found a package in the aur repos: dkms-8192cu which was supposed to have a patched version. However, after installing it still didn’t work. Also downloading the driver from the realtek website didn’t work. There is some stuff on patching on the aircrack-ng website, but it actually is mentioning injection of frames and doesn’t really look to be what I exactly need.
Than I bought the Airpcap Classic and the Airpcap Tx to see what they could do. First of all, they have zero linux support so that already is a big drawback since l need to use it from the Pi’s. However even in windows the airpcap’s only capture db and dbm noise and signal quality. It does receive some data at dbm noise level, but it’s worthless since it is always at -100 level. I can boot the Airpcap classic and tx have zd1211B chipset so I can boot them on zd1211rw driver but this also gives no dbm signal value or anything else.
So my question is, what exactly determines what’s in the radiotap header? I guess it would be all in the driver, but I need to be exactly sure before I write off every ath9_htc driver based adapter. I’m about to purchase another adapter which runs on carl9170 driver, however I can’t find no guarantee anywhere that it will give me those values. What I did find in the literature is that the madwifi driver gives (or was giving) noise levels, however it is acquired by Atheros so the project stopped and all websites are suggestion just to use ath9k or ath5k drivers. I tried to install it but I failed because it seems to be really outdate software since the project stopped.
It would be of really big help if someone can explain me what exactly determines what’s inside the radiotap headers, and also if someone could share any experience on when they did capture more than only dbm signal strength values from linux.
I have recently came across an adaptor that would allow me to use laptop memory on my desktop. See item below:
http://www.amazon.co.uk/Laptop-Desktop-Adapter-Connector-Converter/dp/B009N7XX4Q/ref=sr_1_1?ie=UTF8&qid=1382361582&sr=8-1&keywords=Laptop+to+desktop+memory
Both the desktop and the laptop use DDR3.
My question is, are this adapters reliable?
I have 8 GB available and I was wondering if they could be put to use in my gaming rig.
The desktop is an i7 machine generally used for gaming and some basic development.
The adapter should be reliable based on how it looks. There is not much to it only that it extends the "mini" RAM block to a bigger one. You can make the analog with A-B USB cables.
What you should also consider is if both RAM devices use the same frequency and possible heat issues as you will have to cool down the laptop memory more that if it was desktop size. This is because a lot of current goes trough smaller size compared to the desktop based RAM blocks. Then again you have the extension board to handle and disperse some of the heat so if you are not having some really extensive RAM operations you should be fine but you should check what is the working frequency on both of them. For example if the laptop one is faster than the maximum one your computer can support then you won't get that faster performance and the RAM block will work with the frequency of the system bus but if it is slower then the system bus will work on that frequency.
Use standard things on this module as reference to calculate the width. Measure it on image and scale to a reference item and check on your system. Use contacts or the lock in grooves to do the scaling since they are of standard dimensions on all modules. Or the module length...
I am very enthusiastic in writing device drivers for a microcontroller(like PIC, Atmel etc).
Since I am a newbie in this controller-coding-area I just want to know whether writing device drivers for controller is same as we write for linux( or any other OS) ?
Also can anyone suggest some online device driver building tutorial for the same ..?
Thanks,
If you are thinking about developing the device drivers to interface your device with a host computer (probably using USB), then most of the microcontrollers nowadays implement default classes that rely on native drivers.
A concrete example:
If you use a PIC18F4555, you can use the regular HID (human interface device) windows driver to communicate with your microcontroller (given you implemented it correctly). No need to develop any driver.
Writing a device driver for an MCU is a pretty far cry from writing it for a OS. Most MCUs won't have an OS running on them at all. You'll generally end up writing some low level Interrupt Service Routines (ISRs) and filling up buffers, that your application software will end up emptying. You don't have to fit into any device driver paradigm that an O/S has defined. You basically have to read the datasheet for the device you are wanting to interface with and read and write to its memory over whatever interface it might use (e.g. SPI, I2C, UART, etc.). Ultimately the device driver ought to provide intuitive function calls to the application software.
If you are using AVR MCU like atmega then you can use vusb (https://www.obdev.at/products/vusb/index.html) for those MCU that don't have any HID and handles the interrupts by connecting D+ and D- pins of the USB to digital I/O ports of the MCU.
The atmegaU2 packages have their own USB communication ports and HID.