I am wondering if someone have an idea about the range of the wi-pi usb wireless adapter, while I am using it with Raspberry Pi and its transmission power is 20 dBm and working in 802.11b.
thanks!
Highly depends on the environment. In open area with line-of-sight it goes to 100m or even further. In indoor environment, WiFi signal may penetrate only a few brick walls.
My experience with the wi-pi is that it is a pile of junk. I have trouble getting 10m range through one brick wall that other adapters have no problem with. It regularly stops working and requires replugging. Completely unusable.
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Good day
The problem:
I am trying to connect/flash/debug a Olimax STM32-E407 dev board over SWD and I am not able
When trying to connect, using CubeProgrammer, I get: "No STM32 Target Found"
What I have tried:
I have connected a ST-link V3 mini to the pinout of the the 20pin header of the Olimax board including 3.3V, GND, SWDIO (PA13/Pin7), SWCLK (PA14/Pin9) and NRST (Pin15).
I am powering the powering the board from a power supply into the power jack
All jumpers and solder bridges are in stock places.
I have also tried manually pulling NRST to ground and doing a full chip erase, but that has not worked either.
I have used these ST-link debuggers on other boards I made and it works perfectly fine
I have 3 Olimax boards and none of them work
Any help would he hugely appreciated.
Debugging problems on microcontrollers have two general common methodes.
Hardware Problems:
In this part, it is highly recommended that use an oscilloscope to monitor circuit.
Make sure the microcontroller is powered with a correct and stable power supply.
Check the soldering quality and there is no short circuit on the board (especially between ground pins and other pins).
Check the NRST pin is high when the board is powered.
Remember that this reset is active low so during programming or debugging this pin should be high. Also, check this pin is debounced with a capacitor.
Also you can check the JTAG pins signals with an Oscilloscope to check if the programmer device is working fine.
Sometimes adding a capacitor between debugging pins and GND increases the bus capacitance and solves the problem. The value of the capacitor should be found by trying.
Software Problems
Check the programmer driver is correctly installed on your PC.
Check the programming method is true(for example maybe the board is designed to be programmed with SWD, not JATG).
Sometimes reducing the programming clock of the programmer solved the problem.
If all of these methods didn't work and you are sure that the board is fine, probably the programmer is broken, so change the programmer with another one.
I have two nucleo boards (F4339ZI and F303K8) and neither of them show up as USB devices when I plug them into a computer via the USB port (CN1 - the USB micro port on the ST-Link, not the USB port for the board itself).
I have tried multiple host USB ports, with and without a USB hub, across two different computers, one running OS X and one running Linux. I have tried at least 6 different cables. The OSX machine is using a USB-C to USB-A converter (if that's the correct terminology). The Linux machine has USB-A ports.
In no case does the device show up using lsusb under Linux or system_profiler SPUSBDataType under OSX. Needless to say STM32CubeIDE and st-info can't see the boards. Other USB devices are functional.
The COM LED is slow blinking red which the manual (https://www.st.com/resource/en/user_manual/dm00244518-stm32-nucleo144-boards-stmicroelectronics.pdf) says means USB enumeration hasn't completed (matching what is seen from the OS level).
The boards successfully run their factory supplied blink programs when powered on.
I have tried (with the F4395I) moving JP3 to VIN so the board doesn't power up which should just leave the ST-Link running - still no enumeration though.
I tried connecting to a USB charger with JP1 off (and JP3 on U5V) and the board powers up and blinky runs. The manual referenced above says:
In case the board is powered by a USB charger, there is no USB enumeration, so the green LED LD6 stays in OFF state permanently and the target STM32 is not powered.
But everything works for me - LD6 goes a steady green as it does when connected to a computer.
Given it happens with multiple computers, OSs, cables and Nucleo boards I assume the error lies with me, the common factor in all the tests. This is my first use of Nucleo boards so I may well have a mis-assumption.
Out of frustration and lacking anything else to try I dug up every micro USB cable I could find. One had chokes on each end and magically, using that cable, everything just works as expected.
Can it be that I have at least 10 broken USB cables? I don't have an easy way to test them but I guess they might not have the data lines wired to save cost if manufacturers assumed people would only charge phones with them. I don't recall where they all came from...they have just accumulated in a box of USB cables.
Perhaps the Nucleo board sensitive to some horrible interference floating around my room?
Sorry for the noise! Broken cable was genuinely one of the things I suspected - but not 6 of them...
I'm a developer for different mobile and backend systems and pretty new to network and hardware stuff. I want to build a system/network with 6 cameras placed 100m away in the field, which I want to control with a web interface. I know how to build such interfaces, but I have no clue how to connect the hardware. I thought about the following:
I need 6 cameras(*infos added below) standing side by side with ca. 1.5m space between. These should be connected to a switch, so a 100m wire (USB or LAN, I prefer LAN) goes to a RPI which can setup the web interface controlling the cameras like ".../whatever/camera-slot-ip-or-number".
As I said in the introduction, I have no clue how to start, because actually webcams using USB as a std, but does they provide wake on LAN features? Or is it better to do it with 6 USB-cams and several RPIs?
I hope someone with a better hardware understanding can help me.
Thanks a lot
Specification for the cameras:
HD is not needed, but it should recognize a 0,5cm round hole in a 50x50cm area properly. The distance between camera and object is 7-10m A color image should transmitted, but there only 2 main-colors.
EDIT:
draft 2.0:
Piping USB through a 100m cable is not easily going to work.
Some models of USB cameras can be used with the Raspberry pi, but the performance (speed of taking a picture, and image quality too) are better with the 'native' raspberry pi camera.
The Pi also has a built-in H.264 video encoder, so you can stream live video with relative ease if you want to. A quick and brute way of doing that is to pipe the output from the built-in raspivid application to your own application that then handles flow control and pipes the data further to a socket.
If wifi does nto work for you, then you could pick some other raspberry pi model with an ethernet interface and go that way.
Also, the cost of additional Raspberry Pis (especially the zero w) is so low that the easiest and most cost efficient thing might just be to one raspberry pi camera on 6 raspberry pi's. If connecting them with Wifi works in your application, you can use the Zero W model and then you just need to feed power to them via cable.
Thank you for the updated information. I am pretty much in agreement, I think, with Sami's answer but wanted to add a few more details that are a bit big and unwieldy for a comment.
If you look across the top of your diagram, you have 6 stations at 1.5m intervals, so the width of your diagram is 7.5m. That is easily within wifi range so I am thinking a wifi access point on any of the 6 stations and a 100m Cat 6 Ethernet cable down the length of your diagram to the front-end.
As your processing doesn't sound too involved, you can likely get away with just a Raspberry Pi Zero W and a v2 camera at each station and save a fair bit of money vis-à-vis Raspberry Pi 3B+.
One thing that does concern me is looking for 0.5cm from 7-10m. The lens on the Raspberry Pi camera is pretty wide angle and a 0.5cm hole is going to be awfully small at 10m in a wide angle shot unless at very high resolution. I haven't done the maths, but I think you will be looking for a telephoto lens if such a thing exists... the maths now follows.
The horizontal field of view (FOV) of v2 camera is 62 degrees, so half that is 31 degrees and the camera is 1000cm away. So:
tan(31 degrees) = half the FOV width / 1000
So, at 10m you will get 1200cm of stuff across your image and that will be imaged by 3,280 pixels on the sensor if you shoot at the very highest resolution. So, each pixel in your image will correspond to an area 0.3cm wide whereas you are looking for holes 0.5cm wide - so it will be pretty marginal as to whether you can make it out... maths is subject to revision after a glass of wine later.
I am building a system which uses a remote attached to the RPi with a ribbon cable from about 3ft away.
The remote has buttons on it which connect the Raspberry Pi's
GPIOs to GND.The system works beautifully when I use a breakout board, plugging the ribbon cable into that.
However, when I tried to connect the ribbon straight to the RPi,
pressing 1 button often triggers 2 others.
Why would this happen only at the RPi, but never at the breakout board? Any help would be much appreciated.
Before I could preview the schemtaic circuit of the breakout board. I doubt it is caused by the drive capability of the pi board,you can mesure and compare the voltage on the button end between using breakout board and without it, it's really a hardware issue and only way to solve is to check the schematic circuit and measure. by the way, the question you asked is off-topic here.
We are doing research into running a server on a Pi, and communicating with it via a webapp (over a local network) to control 2-3 servos. It appears that the Rpi has only one hardware configured PWM pin, but this can be worked around via servoblaster. However, since Servoblaster utilizes the Rpi's DMA, will it interfere with the Pi's ability to operate a web server? I apologize if this question is unclear i am somewhat unfamiliar with the software/network concepts involved. Additionally, is there a good resource for understanding the DMA function further?
Thanks in advance for any help.
You can control Servos using Software PWM, which will not require any further hardware or using DMA
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