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I was tired of waiting for the raspberry to load so I thought why not overclock it? I searched up if it's safe to overclock the pi and I saw that you needed a heatsink but I don't have one. Is it safe to overclock without a heatsink?
Google first , in this link you can read much about safety of overclocking (was 1. link in google) also stackoverflow is more for coding errors as for general questions
http://www.raspberrypi.org/introducing-turbo-mode-up-to-50-more-performance-for-free/
important part :
We’ve been doing a lot of work to understand the impact of voltage and
temperature on lifetime, and are now able to offer a “turbo mode”,
which dynamically enables overclock and overvolt under the control of
a cpufreq driver, without affecting your warranty. We are happy that
the combination of only applying turbo when busy, and limiting turbo
when the BCM2835’s internal temperature reaches 85°C, means there will
be no measurable reduction in the lifetime of your Raspberry Pi.
so at 85°c it will downclock for safety
I run a rasberry pi b and as far as overclocking without a heatsink or fan I would only recommend going up to 900 to 950 mhz and keep a eye on the temp better safe then sorry. I overclocked mine without a fan or sink and got around 950mhz 500mhz core 500 mhz sdram 6v overvolt and was running around 51 to 55 degrees Celsius way to hot for my taste anything in the 50s worries me from past pc overclocking experience. I made and I installed a custom heatsink from some laptop parts i had and put additional vent and air holes in the plastic pi case that came in a cana kit then took a 31/2 cooling fan and mounted and sealed it ontop of the pi case and ran a independent usb power cable to it so I would not over draw from my main power source or from the p I am running 1150 mhz proc 550 core 550 sdram 8 volt overdraw at a temp around 41 to 45degrees Celsius. Cant clock my ram at 600mhz gets unstable any tips would be nice.
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I have been trying to learn about how games were made on the old Atari-2600 when the maximum it could address was 8KB and it only had around 127 bytes of memory. I heard that games on the Atari used a technique called Bank Switching, which allows the 6507 (The CPU of the Atari-2600), to access more memory than 8KB. I read the Wikipedia article about it, but I didn't understand how this was accomplished or what it really did.
From what I can understand you basically swap the memory the cpu is using to allow it to access more memory, but how would you keep track of what parts memory you are using?
I read the Wikipedia page about it. I also tried searching for answers here on Stack Overflow but I got no results.
we have system which runs on NXP KE06 chip (MKE06Z64VLH4). It's stationary system, which was developed from primary company, which is not interested in quick bug fixing (there is a lot of bugs) and further development.
Now we have a job to solve a problem, without primary company. We have right now 200 products all over the country. If we want to update mentioned NXP chip, we need to travel to destination, take machine apart,
make and update for NXP chip over SWD (.HEX file) manualy and assemble each machine together again.
We have our controlling system on Raspberry, which is running Raspbian and we have RS-485 half-duplex connection between Raspberry and NXP chip. (which connection continues to CAN --> NXP chip)
We want to solve this problem with software and with current hardware. (With changing all current hardware, with new hardware solution, solves the problem)
Question:
Is possible to make an "remote" updater/flasher with .HEX file, and with current hardware?
FACTS: - we can't ask company for source code
- we have current .HEX file
- we don't want to replace all hardware (200+ pieces)
- we don't know the source code
Is possible to make an "remote" updater/flasher with .HEX file, and with current hardware?
No, because for that to be an option, the MCU must already have a bootloader alternative inside itself.
NXP hates their customers, so they block anyone from reading the manual without logging in... I managed to eventually get it. There is no mentioning of on-chip bootloader support save for SWD. The part can only be programmed by SWD or by a custom bootloader that you'd have to develop.
UART-based bootloaders are not uncommon - you could write one yourself using either UART/RS-485 or CAN, but then you'd have to update the firmware to download the bootloader, so it isn't helpful in this case.
Summary: you need something with SWD on-site or it can't be done.
Also please note that these MCUs typically have anti-copycat protection enabled, preventing you from reading anything out of it. Depending on how they were programmed, this could be present and then the only thing you can do is to erase and flash the whole program.
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I am not sure if I can post a question without code in Stack Overflow. This is a question about how the computer works.
I know it's not slow when watching a movie because the data in storage is copied to memory and used. However, because the storage processing speed is slow, is it not slower than a direct processor accessing and reading the storage? Or does another device act as a copy? I want to know the principle in detail.
The processor access addressable data: units of memory each one identified by an address.
Main memory is addressable: this allows the processor to read from "here" and write "there" and "there", exploiting the full capacity of the main memory.
Without memory, the processor could only use its internal units of storage (registers) but they are of limited size (around 2KiB for x86, but for general purpose registers it goes down to 128 bytes).
Caches are equivalent to memory for this discussion.
Disks are not addressable the same way memory is: this is due to historical reasons (small address space) and performance (reading randomly is worse than planning ahead even for SSD, also there are more commands than Read and Write and some can be executed in parallel).
So disks are either made to write data to main memory (DMA) or there is a fixed location where to write to send commands and a fixed location to repeatedly read from to fetch all the data (PIO).
This read location is small enough to fit into a CPU internal storage unit but once the CPU has the data it must "save" it somewhere for later processing and so this data would end up in memory anyway (PIO is waaaay slower than DMA).
Note that Non Volative Devices are considered a new form of storage, something in between main memory and disks (while main memory won't be phased out by NV devices, because we need scratch memory, disks may be if the NV technology can address the longevity and density problems without affecting performance).
They are addressable like main memory and thus the CPU could read directly from them.
Symbian OS based mobile phones worked this way: the OS executable files were stored in the flash ROM (which is an NV device) and read directly by the CPU without loading them (they were already loaded).
Also note that FWIW, video is played for humans which have a very slow sampling rate. We only need about 24 frames per second to consider a movie smooth, that is easy to sustain even from the network (though it depends on the resolution and format).
So the disk has all the time to serve the reads needed for the playback.
On the contrary, video conversion can be affected by the speed of the disk.
Also, videos are compressed so the CPU must modify the data (meaning it needs to overwrite it or store the result somewhere in main memory) to play the video unless there is a hardware device that can play compressed stream directly and the file format is just right.
In this case, storing the video on an NV device would allow a faster reproduction, without the CPU involved or any copy in memory.
However the speedup is not dramatic, we are shaving off the time needed to read from memory not the time needed to read from the storage device (which is still the dominant factor affecting speed).
That's mostly irrelevant for the frame rates involved when playing for humans.
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.
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Just like any other software development company, we use white boards a LOT. We use it for a wide range of activities — design discussions, project scheduling, brain storming, interviews etc. However, after we're done with the discussions, we end up spending a lot of time just copying the stuff for notes.
Very often we run into two issues --
We don't have sufficient space (at that point, we've to pause the discussion while someone takes notes).
Our time is up and some other team needs to use the conf room ( again, they've to wait till we're done with taking notes).
Sometimes, we end up taking snaps and take notes later.
How have other developers addressed this issue? Has anyone tried using "smart" whiteboards?
Any recommendations?
There are many ways:
Simplest is to just use a camera and take a picture of the whiteboard at critical stages
A more advanced way would be to go fully digital, using a smartboard wall type of solution (ie. big hunking display)
Cheaper solutions work by way of using the computer for the display, a normal projector, and special hardware (like pens) to detect where on the wall you're pointing or doing things
I've tried all three and by far I liked the full display the best, but it is quite expensive in some cases.
A good enough solution is the one that integrates with the computer.
The solution I tried had a suction cup rod that you hung up on the whiteboard, along one side, connected to a computer through a long USB cable.
Then you had special "pens" that were just a normal whiteboard pen with a holder around it. This holder had some kind of radio connection with the rod, and due to the length of the rod, the rod could quite accurately pinpoint the location of the pen on the whiteboard. It also made a clickety sound when you pressed the pen onto the whiteboard, so it knew when you were actually drawing with it.
This was then relayed back to the computer, so everything you drew would be captured, and could be replayed later, line by line if you wished. There was also an eraser that came with it, but it wasn't quite as accurate.
I don't remember the price of the whole setup, but apart from the normal computer, the rest came in under $1000.
The full digital smartboard I've tried was basically a 50" LCD with pens that communicated with the computer. This of course had features such as multiple pages (easily switch back and forth, bring up diagrams from earlier discussions, etc.), full replayability, could stream contents live to participants not in the same room, etc.
There's also setups that use a projector, typically mounted in the ceiling pointing down on the wall, and again communicating with a computer, using the projected display instead of a LCD display. Never tested this.
The cheapest solution is the digital camera way, and since most phones comes with adequate cameras these days you already have what you need.
I use my smartphone camera and Evernote.com ... it's a cheap solution but I'm not fully pleased with it. Like you I think there has to be a better solution.
I already used a smartboard based on a projector and sprecial pens, but I had the feeling, that it was not fully accepted by the team, they try to avoid writing on it, etc. I think it just doesn't feels right.