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by jwatte
Tue Feb 17, 2015 5:28 am
Forum: Beginners
Topic: Connecting to WiFi -- wpa_supplicant trouble
Replies: 0
Views: 754

Connecting to WiFi -- wpa_supplicant trouble

I've tried to follow the available wpa_supplicant resources on this forum and the greater internet. I have the ralink 7601 module installed, and it's recognized by my kernel (for RPi 2) When I manually run wpa_supplicant, it correctly connects to my access points: wpa_supplicant -c /etc/wpa_supplica...
by jwatte
Sat Feb 14, 2015 5:58 pm
Forum: Troubleshooting
Topic: Dynamode USB Wifi Dongle issues
Replies: 393
Views: 165773

Re: Dynamode USB Wifi Dongle issues

Is there an apt-get install package name to get the right version of the linux sources? I'd like to be able to easily re-build it myself. I have this same adapter, and the default raspbian for the Pi 2 is .5-v7+; doing a apt-get upgrade gets me to .7-v7+ while the binary in the above link is for .6-...
by jwatte
Mon Dec 29, 2014 5:30 pm
Forum: Advanced users
Topic: What is the right API for camera access?
Replies: 10
Views: 2735

Re: What is the right API for camera access?

If the library works, that looks interesting!

The drama in the thread was a little rich for my stomach this early in the morning when on my first cup of coffee, though :-)
by jwatte
Sun Dec 28, 2014 10:30 pm
Forum: Advanced users
Topic: What is the right API for camera access?
Replies: 10
Views: 2735

Re: What is the right API for camera access?

Thanks for the info! I may go with MMAL then. Python is not something I'm looking at anymore, because I'm looking to avoid additional overhead. As an example: I once wrote a remote control application on top of Python and D-Bus and PyGame, with a 1280x800 display for a 800 MHZ Model B. It ran at abo...
by jwatte
Sat Dec 27, 2014 8:08 pm
Forum: Advanced users
Topic: What is the right API for camera access?
Replies: 10
Views: 2735

Re: What is the right API for camera access?

Thanks for the pointer!
What's the reasoning behind "activate raspberry pi camera" in the raspiconfig not actually adding this modprobe to boot?

Separately -- are there known differences in efficiency when using v4l2 versus mmal?
by jwatte
Sat Dec 27, 2014 5:35 pm
Forum: Advanced users
Topic: What is the right API for camera access?
Replies: 10
Views: 2735

What is the right API for camera access?

I want to access the Pi camera with as little CPU overhead as possible. This is because I want to try a bit of real-time image detection/processing. The camera doesn't expose a /dev/video* device. What's wrong with Video4Linux2? Looking around, I found the userland tools (now open source,) followed ...
by jwatte
Tue Dec 23, 2014 11:22 pm
Forum: HATs and other add-ons
Topic: What's the use of U14 (dual PNP transistors) around P-FET?
Replies: 4
Views: 2677

Re: What's the use of U14 (dual PNP transistors) around P-FE

Oh, I see! The idea is to provide a diode even when both Vin and Vout are kept above GND. I've only seen the variant used as reverse-power-accident-prevention before, which doesn't need any of the extra components -- a single P-MOSFET is enough (perhaps with a Zener and resistor if you expect signif...
by jwatte
Tue Dec 23, 2014 6:12 pm
Forum: HATs and other add-ons
Topic: What's the use of U14 (dual PNP transistors) around P-FET?
Replies: 4
Views: 2677

What's the use of U14 (dual PNP transistors) around P-FET?

In the HAT specifiction, this diagram is shown: https://github.com/raspberrypi/hats/blob/master/zvd-circuit.png I have previously only seen and used the "ideal diode" implemented with a single low-Rdson P-channel MOSFET and a weak resistor to ground. What is the use of the pair of PNP transistors (U...
by jwatte
Sat Aug 16, 2014 5:25 am
Forum: C/C++
Topic: OpenGL ES Issue
Replies: 13
Views: 2427

Re: OpenGL ES Issue

And the solution is: When using OpenGL ES 2.0, and calling eglCreateContext(), you have to pass context attributes as the last parameter to eglCreateContext() that specify EGL_CONTEXT_CLIENT_VERSION, 2, EGL_NONE. If you don't do this, the only thing you'll see to tell you that something's wrong is t...
by jwatte
Sat Aug 16, 2014 5:18 am
Forum: C/C++
Topic: OpenGL ES Issue
Replies: 13
Views: 2427

Re: OpenGL ES Issue

FWIW, I have what seems to be this same issue. I go through the dispmanx setup code, which works fine. I then call glClearColor() and glClear(), and neither of them generates a GL error. I then call glCreateShader(), and it returns 0. There is no GL error set, before or after. Building and running h...
by jwatte
Fri Aug 15, 2014 2:25 am
Forum: Graphics, sound and multimedia
Topic: general advice using openvg with C
Replies: 3
Views: 858

Re: general advice using openvg with C

I pointed g++ at /opt/vc for include/ and lib/
However, I can't find the shapes.h and fontinfo.h include files -- where are they supposed to come from?
by jwatte
Thu Aug 07, 2014 1:24 am
Forum: Troubleshooting
Topic: My .desktop file doesn't work in autostart
Replies: 2
Views: 724

Re: My .desktop file doesn't work in autostart

I had to track this down all on my lonesome.
In case anyone else has the same problem: I got the app to start and stay started by adding "StartupNotify=false" to the .desktop file.
by jwatte
Tue Aug 05, 2014 12:00 am
Forum: Troubleshooting
Topic: My .desktop file doesn't work in autostart
Replies: 2
Views: 724

Re: My .desktop file doesn't work in autostart

Where do you think I could ask this question about why my .desktop auto-started program crashes, while it works fine when normally starting or double-clicking, and how to debug the cause of this problem?
by jwatte
Sun Aug 03, 2014 6:59 pm
Forum: Troubleshooting
Topic: Python spidev doesn't seem to send bytes?
Replies: 1
Views: 2005

Re: Python spidev doesn't seem to send bytes?

This one's solved! Another utility that ran on boot had grabbed GPIO10, and when GPIO10 is exported, the SPI peripheral cannot "steal" it.
Unexporting this GPIO before opening the SPI device made it work.
by jwatte
Sun Aug 03, 2014 6:13 pm
Forum: Troubleshooting
Topic: Python spidev doesn't seem to send bytes?
Replies: 1
Views: 2005

Python spidev doesn't seem to send bytes?

I'm using the spidev from http://www.100randomtasks.com/simple-spi-on-raspberry-pi in Python. The module is from http://github.com/doceme/py-spidev. I can read bytes from the SPI slave just fine, but the Raspberry Pi seems to send only 0xFF (or, more likely, the MOSI is held high by some config some...
by jwatte
Sun Aug 03, 2014 6:23 am
Forum: Troubleshooting
Topic: My .desktop file doesn't work in autostart
Replies: 2
Views: 724

My .desktop file doesn't work in autostart

I have created a .desktop file for a simple utility I wrote in python2 and pygame. When I start the utility from the command line, it works great. When I start the utility by double-clicking the .desktop file, it works great. However, when the system auto-starts, I can see the desktop load, see the ...
by jwatte
Wed Mar 05, 2014 3:44 am
Forum: Troubleshooting
Topic: GPIO output is only 1.6V?
Replies: 2
Views: 1314

Re: GPIO output is only 1.6V?

Aaaand the solution is that the GPIO number should be the Broadcom GPIO signal number, not the RPI header pin number.
So, if I use GPIO4, and measure on pin 7, all is well. And why I saw a difference at all when using another pin, I have no idea. Sensitive instruments and leakage voltage?
by jwatte
Wed Mar 05, 2014 3:41 am
Forum: Troubleshooting
Topic: GPIO output is only 1.6V?
Replies: 2
Views: 1314

GPIO output is only 1.6V?

I am using a Rev B Pi to run XBMC, using the raspbmc install. This part works okay. I am feeding it 5V through pin 2 (and ground through pin 6) rather than powering through USB-in. This comes from a 1.5V switching regulator that happens to be available on an extension board I've built to control som...
by jwatte
Sun Dec 01, 2013 7:48 am
Forum: Advanced users
Topic: raspbian XBMC and GPIO output -- plugins?
Replies: 0
Views: 707

raspbian XBMC and GPIO output -- plugins?

I'm using the RPi with XBMC. It is playing to a display and some powered speakers that use power when idle. I know how to build a simple relay that is pulled by a MOSFET that in turn is driven by a GPIO pin of the RPi. I can put this is a nice project box to make sure the 120V mains isn't touched by...
by jwatte
Thu Jan 10, 2013 4:59 am
Forum: General programming discussion
Topic: libusb based program runs into problems
Replies: 3
Views: 1090

Re: libusb based program runs into problems

Hey, don't everybody answer all at once, you hear? :-) The same program, sitting idle and just polling the Atmega, runs fine on Intel, but runs into trouble when running on the Pi. Typically after a minute or two, doing between fifty and two hundred polls a second. Is the USB register-level interfac...
by jwatte
Tue Jan 08, 2013 6:20 am
Forum: Beginners
Topic: UART from GPIO connection
Replies: 2
Views: 1421

Re: UART from GPIO connection

This is a little late, but Arch uses the newer "systemd" way of starting processes, rather than init.

This command will remove a particular getty process:

systemctl disable [email protected]
systemctl stop [email protected]
by jwatte
Tue Jan 08, 2013 4:22 am
Forum: General programming discussion
Topic: libusb based program runs into problems
Replies: 3
Views: 1090

Re: libusb based program runs into problems

Slight update: The "return the last packet" part is actually just "the remote device sends single-byte dummy packets because no command has been received." I would expect this to be a timing bug in my own code provoked by the different CPU, but I haven't yet found it, so any information anyone might...
by jwatte
Tue Jan 08, 2013 3:22 am
Forum: General programming discussion
Topic: libusb based program runs into problems
Replies: 3
Views: 1090

libusb based program runs into problems

I have an Atmega32u4 based microcontroller, driving a number of servos for a walking robot. This works fine running Arch Linux on an Intel based PC. It uses basically no CPU, just sits in a loop to delay, issue a read and a write request, delay, ... On Raspberry Pi model B version 1, using Arch Linu...
by jwatte
Sat Nov 10, 2012 11:55 pm
Forum: Arch
Topic: Problems configuring wireless
Replies: 14
Views: 6506

Re: Problems configuring wireless

I'm running into similar problems. So far, I've had to install: wpa_supplicant iw wpa_actiond netcfg dialog ifplugd I've also enabled services wpa_supplicant and net-auto-wireless, and created a profile in /etc/network.d (the directory was created when I installed netcfg, I think.) I'm still not at ...
by jwatte
Sat Nov 10, 2012 1:57 am
Forum: Troubleshooting
Topic: How is wpa_supplicant, wpa_cli, and systemd interacting?
Replies: 4
Views: 4381

How is wpa_supplicant, wpa_cli, and systemd interacting?

I'm running arch with alarm (done a pacman -Syu to get latest everything) on an original model B. I'm using a Belkin USB adapter which is really a Realtek rtl8188su chip, which is recognized with the r8712u module. I want to do it all from the command line (not running a GUI, as this Pi won't be hav...

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