Exact Duplicate: https://stackoverflow.com/questions/473465/firefox-plugin-to-simulate-slow-internet-connection
How do I simulate a slow internet connection (Edge/3g) on a Mac? Is there a Firefox plugin?
On a Mac or BSD, use:
sudo ipfw pipe 1 config bw 350kbit/s plr 0.05 delay 500ms
sudo ipfw add pipe 1 dst-port http
And to reset to your initial settings:
sudo ipfw flush
Apple now have an official developer tool called Network Link Conditioner which simulates different network conditions. It has some more powerful features that alternatives like SpeedLimit and Charlie — for example it can simulate packet loss and DNS delays as well as bandwidth and latency — and it is free.
Network Link Conditioner is provided with Xcode, with is a free download but is also a very large download!
Ref: https://apple.stackexchange.com/questions/24066/how-to-simulate-slow-internet-connections-on-the-mac
SpeedLimit does the trick for me.
Charles and Fiddler are HTTP proxies that can throttle your speed, among other things. You can even tell your iPod or iPhone to use them, and capture all the traffic coming & going.
When I was evaluating how a piece of software would work with a bad cell-card connection, I wrapped some tin foil around the antenna. It sounds dumb, but it worked really well; the signal dropped down to a single bar but was not gone completely.
I also tried putting the laptop in a microwave which ended up being not nearly as effective.
Not that I know of. If you want to see how things look when they're loading you can use firebug and set breakpoints in the javascript, or breakpoints on your server. I always use this technique to see how things look when they're loading.
Another option is NetLimiter, I've heard it works but haven't tried it myself
http://www.netlimiter.com/
Related
I am trying to make some custom firmware for a MIDI controller (AKAI LPD8).
There is an STM32F102R8T6 chip in the unit.
I am trying to reach it with a programmer to wipe it, but it seems to not be responsive.
Some information and thing I have tried:
The firmware that came with the unit works, so the chip is not broken
Removed the components connected to the programming pins (PA9-PA10 and PA13-PA14)
I am able to pull BOOT0 high and have it not run the main program, but I am however not able to get a life sign using either an ST-Link2(clone) connected to PA13/14, nor a USB to serial adapter connected to PA9/PA10, so I am not sure what mode it is in
The connection has been checked, and RX-TX etc is the correct way around (but also for the sake of trying it all, I reversed the connections as well...).
Tried both the STM32CubeProgrammer and stm32flash, but none connects.
I am actually not sure if AKAI have locked the chip in such a way that you cannot even do a full chip erase and use the chip for something new? The NRST pin is strangely not doing anything to the running of the firmware either when I try to pull it low.
Is there a way to reprogram these chips when they come off of a commercial product, or are they permanently locked?
Any solution/tips?
Many of the STM32 parts have "proprietary code read-out protection" (google PCROP) which but you might be lucky and they haven't enabled it in the option bytes. Read the documentation for that and the bootloader documentation and get a good idea of what you expect it to do if it is enabled and if it isn't.
If you have a scope, try watching the SWD/JTAG pins to see if there is any response from the device. (If you aren't even sure if it is in reset then scope the crystal if there is one).
If you haven't got a scope, you might be able to to verify what it is doing by seeing if it sets the pins and pull-resistors to how they would be expected to be in the bootloader mode, eg: UART TX should be high if it is enabled, even it it isn't transmitting anything. Put a strong pull-down (~1k) on there and see if it still reads high.
After hours of trying different ways of making it work (also tried the alternate mapping of the UART port), and probed the TX pin as suggested by Tom V to no avail, I have given up working on that specific chip and ordered an upgrade from the STM32F4 family instead to replace it with. A lot more power and useful peripherals.
A bit of a non-answer to the specific question. Frustrating to not have found out what was wrong (chip or approach) but being mindful of the sunk cost fallacy, I think it was best to just replace the chip with a fresh one and start development from there.
I have been having an issue in my project with LWIP. I am using a ST32F4 MCU and running with no OS. The network seems to run fine, the protocols all work, but then (usually a day or two later) the stack just stops running. It seems to happen when trying to make a new connection, but I can't confirm that because I haven't been able to locate what is causing it in the code.
Has anyone else come across this issue? I think it may be the same as this guy.
Do you call any LwIP functions from any interrupt-handlers, like UART etc?
How do you feed packets in/out of LwIP? Directly via interrupt handlers, or do you push them in from your "main-loop" ?
Lock-ups can also be signs of double free, or use-after-free of pbufs.
I also experiences that one project was unstable with wierd random locks-ups when running at the top-rated frequency of the STM32. If I clocked my STM32 at 100MHz instead of 120MHz, all my problems went away....
I've got a Behringer X32 rack, which uses an extension of the OSC (Open Sound Control) protocol. This particular rack communicates via UDP packets on port 10023. A fellow named Patrick Maillot actually has some pretty extensive albeit unofficial documentation of the protocol, including multiple executables you can download to interact with the system (outside of the official Behringer apps).
What I would like to do is pretty simple, though I'm having a hard time getting up to speed with this. I want to be able to mute and subsequently un-mute Mute Group 1 on my device. The mute group is already set up; all I want to do is utilize the protocol to either activate or deactivate it.
I can successfully connect to the rack using the X32_Command.exe program. But wading through the documentation, here's what I came up with as my best guess for which commands I should be sending:
/config/mute/1/ON
/config/mute/1/OFF
However, I don't think I have the syntax right (or maybe I've just got the wrong set of commands altogether), because those don't seem to do anything. In the X32_Command.exe console application I appear to receive the following responses when issuing those commands, respectively:
->X, 20 B: /config/mute/1/ON~~~
->X, 20 B: /config/mute/1/OFF~~
However, nothing actually happens on the rack. The mute group isn't affected at all when I issue these commands. How do I get this working? What am I doing wrong?
Just saw this (better late than never). The correct syntax for X32_Commmand.exe would be (as stated in the documentation):
/config/mute/1 ,i 0
/config/mute/1 ,i 1
I want my students to use Enchanting a derivative of Scratch to program Mindstorm NXT robots to drive a pre-programmed course, follow a line and avoid obstacles. (Two state, five state and proportional line following.) Is Enchanting developed enough for middle school students to program these behaviors?
I'm the lead developer on Enchanting, and the answer is: Yes, definitely.
The video demoing Enchanting 0.0.4 shows how to make a proportional line follower (and you could extend it to use a PID controller, if you wish). If you download the latest version, 0.2.2, it includes a sample showing a two-state line follower (and you can see a video and download code here). You, or with some instruction / playing around, a middle-schooler, can readily create a program to do n-states, and, especially if you follow a behaviour-oriented approach, you can avoid obstacles at the same time.
As far as I know, yes and no.
What Scratch does with its sensor board, Lego Wedo, and the S4A - Scratch for Arduino - version as well as, I believe, with NXT is basically use its remote sensor protocol - it exchanges messages on TCP port 42001.
A client written to interface that port with an external system allows communication of messages and sensor data. Scratch can pick up sensor state and pass info to actuators, every 75ms according to the S4A discussion.
But that isn't the same as programming the controller - we control the system remotely, which is already very nice, but we're not downloading a program in the controller (the NXT brick) that your robot can use to act independently when it is disconnected.
Have you looked into 12blocks? http://12blocks.com/ I have been using it for Propeller and it's great and it has the NXT option (I have not tested)
It's an old post, but I'll answer anyway.
Enchanting looks interesting, and seems to be still an active project.
I would actually take the original Scratch (1.4), as it's is more familiar and reliable.
It's easy to interface hardware with Scratch using the remote sensor protocol. I use a simple serial interface (over a USB-adapter) which provides 3 digital inputs and 3 digital outputs. With that, it's possible to implement projects such as traffic lite, light/water/heat-sensors, using only lets, resistors, reed-contacts, photo-transistors, switches, PTSs.
The costs are < 5$
For some motor-based projects like factory belts, elevator, etc. There is not much more required, a battery and a couple of transistors/relais/motor driver.
Developing an app that uses data synchronization. Sending images (even resized) takes time if it's done over slow internet connection. Thinking, it would be best first to check internet speed, and sent data only if the speed is acceptable. There's Apple Reachability class but it only has method for checking wifi is on. I guess for me, it would be enough to ping a host and grab delay information out of the ping cmd result. That delay info I would use for deciding is it worth to send data now or to wait.
Reachability or ping won't tell you how fast or slow the file will be transmitted. That is a function of ping_time + (file_size / bandwidth). For any large file, the ping_time is much smaller than file_size/bandwidth.
The easiest way to measure this is for the app to download and upload a not-too-small-not-too-large file and decide if in fact the upload and download speeds are "fast enough".
Doing this is fairly involved, however Apple has a complete working example program here:
https://developer.apple.com/library/mac/#samplecode/SimplePing/Introduction/Intro.html#//apple_ref/doc/uid/DTS10000716-Intro-DontLinkElementID_2