Search found 83 matches

Go to advanced search

by zhanghaijason
Fri Feb 21, 2020 12:26 am
Forum: General discussion
Topic: Change boot up option in cmdline.txt or config.txt
Replies: 1
Views: 196

Change boot up option in cmdline.txt or config.txt

Hello,
I used a operating system(similar to the noob) released by other company. After I use

Code: Select all

sudo raspi-config
and changed the boot option to CLI and rebooted. The pi can't boot any more. I am wondering how could I change it back to desktop option in cmdline.txt or config.txt. Thanks for your help!
by zhanghaijason
Mon Jul 29, 2019 10:08 pm
Forum: Other
Topic: WIFI setting [Ubiquity ROS]
Replies: 1
Views: 2661

WIFI setting [Ubiquity ROS]

Hello everyone, I used the ros preinstalled image https://downloads.ubiquityrobotics.com/pi.html for on pi 3 my research. However, they have configured their default wifi to use in the image. I configured my own wifi settings at /etc/wpa_supplicant/wpa_supplicant.conf. But sometimes it connects to t...
by zhanghaijason
Wed Feb 07, 2018 9:24 pm
Forum: General discussion
Topic: No internet connection even with internet cable on Pi3
Replies: 9
Views: 1347

Re: No internet connection even with internet cable on Pi3

You seem to have lost the first half of wpa_supplicant.conf. Try this: ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev update_config=1 country=US network={ ssid="Forpi" psk="mypassword" key_mgmt=WPA-PSK } Don't forget the change the country code and psk. This sample assumes your router runs...
by zhanghaijason
Wed Feb 07, 2018 9:24 pm
Forum: General discussion
Topic: No internet connection even with internet cable on Pi3
Replies: 9
Views: 1347

Re: No internet connection even with internet cable on Pi3

You seem to have lost the first half of wpa_supplicant.conf. Try this: ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev update_config=1 country=US network={ ssid="Forpi" psk="mypassword" key_mgmt=WPA-PSK } Don't forget the change the country code and psk. This sample assumes your router runs...
by zhanghaijason
Wed Feb 07, 2018 5:04 pm
Forum: General discussion
Topic: No internet connection even with internet cable on Pi3
Replies: 9
Views: 1347

Re: No internet connection even with internet cable on Pi3

To get accurate troubleshooting advice, please state clearly which Operating System is running on your RPi. The content of your wpa_supplicant.conf is not related to establishing an internet connection via an Ethernet cable. Hi, it is jessie. But before I configured that file, I was able to connect...
by zhanghaijason
Wed Feb 07, 2018 5:01 pm
Forum: General discussion
Topic: No internet connection even with internet cable on Pi3
Replies: 9
Views: 1347

Re: No internet connection even with internet cable on Pi3

davidcoton wrote: ↑
Wed Feb 07, 2018 9:40 am
 So, if a reboot of the Pi doesn't fix it, try rebooting the router. If it still doesn't work, post the contents of your wpa_supplicant.conf.
Hi it is

Code: Select all

network={
  ssid="Forpi"
  psk="mypassword"
  key_mgmt=WPA-PSK
}
by zhanghaijason
Wed Feb 07, 2018 12:58 am
Forum: General discussion
Topic: No internet connection even with internet cable on Pi3
Replies: 9
Views: 1347

No internet connection even with internet cable on Pi3

Hello, I followed sudo nano /boot/wpa_supplicant.conf to make the pi3 defaultly connect to my wifi. However it failed. Then I use the monitor to see what's going on. It showed the pi3 cannot find any wifi. Finally I tried to use a internet cable, still no internet connection. I am pretty sure that t...
by zhanghaijason
Wed Mar 01, 2017 4:25 am
Forum: General discussion
Topic: Is there a Pi battery?
Replies: 4
Views: 1067

Re: Is there a Pi battery?

There is no official one that I am aware of however there are some that work. Like this https://www.adafruit.com/products/1565 There are also some lipo packs but be careful with those make sure you know exactly what you are getting. I would figure out what your current draw is, all peripherals, etc...
by zhanghaijason
Wed Mar 01, 2017 4:24 am
Forum: General discussion
Topic: Is there a Pi battery?
Replies: 4
Views: 1067

Re: Is there a Pi battery?

Heater wrote:You mean like any common or garden, off the shelf, mobile phone power bank?

http://www.ebay.com/sch/i.html?_from=R4 ... k&_sacat=0

thank you!
by zhanghaijason
Sun Feb 26, 2017 2:32 am
Forum: General discussion
Topic: Is there a Pi battery?
Replies: 4
Views: 1067

Is there a Pi battery?

Hello, I use my pi 2 on a mobile robot. I use a 12V battery and a 5V output voltage regulator to power the Pi. But it turns out that almost for every month I may break a Pi, with only the ACT led yellow, no red LED on. And and not boot even with a power cable. So could anyone recommend a portable ba...
by zhanghaijason
Sat Nov 05, 2016 2:15 am
Forum: Beginners
Topic: Sampling rate of ADC with SPI
Replies: 5
Views: 2988

Sampling rate of ADC with SPI

Hello, I am trying to see how fast could raspberry sample the analog signal with an ADC chip. I have searched on the forum that it seems 50ksps is the fastest. But could anyone tell me how to calculate it? I know some of it: Suppose an ADC chip needs 10 clock cycles to finish 1 reading and the maxim...
by zhanghaijason
Wed May 25, 2016 6:27 am
Forum: Beginners
Topic: Can anyone recommend me an UAV?
Replies: 1
Views: 435

Can anyone recommend me an UAV?

Hello,
I am doing research about vision based control and now I want to test my algorithm on UAV. Could anyone recommend me an UAV so that I can use the raspberry pi to capture images and do computation then send UAV the required speed？ Thanks
by zhanghaijason
Thu May 19, 2016 12:21 am
Forum: Beginners
Topic: How to compile code using I2C and MPU6050 library
Replies: 7
Views: 1422

Re: How to compile code using I2C and MPU6050 library

This code is not configured like a normal library, so it does not fit the general methods I described. So you would have saved some time if you had included the link in the first post. Looking at the Makefile it seems like the "library" part of the code is the two files "I2Cdev.o MPU6050.o", so bas...
by zhanghaijason
Wed May 18, 2016 5:57 pm
Forum: Beginners
Topic: How to compile code using I2C and MPU6050 library
Replies: 7
Views: 1422

Re: How to compile code using I2C and MPU6050 library

You have said very little about how you acquired those libraries so its difficult for me (or anyone else) to speculate on how they should be used. Have you downloaded the sourcecode and compiled them yourself with for example "./configure" and then "make" ? Hello topguy I downloaded the PiBits libr...
by zhanghaijason
Wed May 18, 2016 6:33 am
Forum: Beginners
Topic: How to compile code in terminal
Replies: 4
Views: 852

Re: How to compile code in terminal

Typically, in the product directory, you enter: make clean ./configure make sudo make install ... follow the directions from PiBits. But, it looks like it can't find the libraries... Thanks for your reply first. But I think you misunderstood. Now I am compiling the PiBits with other libraries, so s...
by zhanghaijason
Wed May 18, 2016 1:27 am
Forum: Beginners
Topic: How to compile code in terminal
Replies: 4
Views: 852

How to compile code in terminal

Hello, I am using the raspi to interface with MPU6050. Previously I use the PiBits library and the makefile written by them to compile it. Now in my new code, there is "#include I2Cdev.h" "#include MPU6050.h" . How could I compile the code? There are "I2Cdev.h, I2Cdev.o, I2Cdev.cpp, MPU6050.h, MPU60...
by zhanghaijason
Wed May 18, 2016 12:35 am
Forum: Beginners
Topic: How to compile code using I2C and MPU6050 library
Replies: 7
Views: 1422

Re: How to compile code using I2C and MPU6050 library

Any library consist of two parts, the header file "A.h" , and normally a binary part that either can be built for static linking or dynamic linking, "libA.a" and/or "libA.so". The binary files you will usually find in "/usr/lib" ( or "/usr/local/lib" if you have compiled them yourself ). To add thi...
by zhanghaijason
Fri May 06, 2016 6:53 pm
Forum: Beginners
Topic: How to compile code using I2C and MPU6050 library
Replies: 7
Views: 1422

Re: How to compile code using I2C and MPU6050 library

Any library consist of two parts, the header file "A.h" , and normally a binary part that either can be built for static linking or dynamic linking, "libA.a" and/or "libA.so". The binary files you will usually find in "/usr/lib" ( or "/usr/local/lib" if you have compiled them yourself ). To add thi...
by zhanghaijason
Tue May 03, 2016 5:37 pm
Forum: Beginners
Topic: How to compile code using I2C and MPU6050 library
Replies: 7
Views: 1422

How to compile code using I2C and MPU6050 library

Hello, I have a question about compliation. Here are the libraries I use: #include <iostream> #include <ctime> #include <cstdlib> #include <fstream> #include <sstream> #include "raspicam_cv.h" #include <stdio.h> #include <stdint.h> #include <unistd.h> #include "I2Cdev.h" #include "MPU6050.h" #includ...
by zhanghaijason
Sun Jan 31, 2016 1:16 am
Forum: Camera board
Topic: Do not move object but different images
Replies: 0
Views: 359

Do not move object but different images

Hello, I am using the raspicam-0.1.3 library to control the camera. But I found that even I do not move the object and the camera. Just let the camera take images continuously with FPS about 60. The light intensity of some areas of the images are different. How could it be? And what parameters of ra...
by zhanghaijason
Wed Jan 27, 2016 2:09 am
Forum: Beginners
Topic: Pi freezes for certaion large code
Replies: 7
Views: 1111

Re: Pi freezes for certaion large code

New information. Now I know how to make it work. Before running the code, first compile some large code which will cost a lot of time. Compile and "ctrl+C" after a few seconds. Repeat for about 4 or more times. Then compile it and wait until it finishes compilation. After that, I can run the code wh...
by zhanghaijason
Wed Jan 27, 2016 1:32 am
Forum: Beginners
Topic: Pi freezes for certaion large code
Replies: 7
Views: 1111

Re: Pi freezes for certaion large code

More information. If I run the code with the monitor connected. It can work. But if I run it with my laptop through VNC and wifi, it will freeze. I think the reason must be the wifi. The usual answer on the wifi is that you are drawing too much power. If you are burying the system with computations...
by zhanghaijason
Wed Jan 27, 2016 1:30 am
Forum: Beginners
Topic: Pi freezes for certaion large code
Replies: 7
Views: 1111

Re: Pi freezes for certaion large code

The A+ is never going to give decent compilation speeds (let alone the added power and resources needed for wifi aand VNC). If you really must compile on a Pi (rather that cross compile on a PC), then invest in a Pi2 and an HDD (to run your system on) and your compilations will run considerably fas...
by zhanghaijason
Tue Jan 26, 2016 9:48 pm
Forum: Beginners
Topic: Pi freezes for certaion large code
Replies: 7
Views: 1111

Re: Pi freezes for certaion large code

More information. If I run the code with the monitor connected. It can work. But if I run it with my laptop through VNC and wifi, it will freeze. I think the reason must be the wifi.
by zhanghaijason
Tue Jan 26, 2016 2:38 am
Forum: Beginners
Topic: Pi freezes for certaion large code
Replies: 7
Views: 1111

Re: Pi freezes for certaion large code

Now If I do not print too much message on the screen, it can work fast. But I really feel that the pi is slow, sometimes it is killing me to wait especially compiling the code.
But with the wifi on, it still freeze....

Go to advanced search